This ancient predator had two spiny appendages sticking out of its face. This creature Anomalocaris canadensis may have been the freakiest thing to ever haunt the sea. For decades, scientists thought it used those strange limbs to snatch trilobites off the seafloor. The beast could then crush and eat these crunchy snacks. But a new study hints that A. canadensis instead used its spiny limbs to swiftly hunt soft prey. 



Researchers shared their new findings on July 12. The work appeared in Proceedings of the Royal Society B.





A. canadensis means the abnormal shrimp from Canada. It prowled the seas roughly 500 million years ago. Only about as long as a housecat, it still was one of the biggest animals of the Cambrian Period. (The Cambrian ran from about 540 million to 485 million years ago.) That makes A. canadensis one of the earliest top predators.





These sea monsters were like the orcas or great white sharks of their time, says Jakob Vinther. He did not take part in the new study. But he is a paleontologist at the University of Bristol in England. 



Some researchers thought A. canadensis hunted another iconic Cambrian critter the trilobite. Thats because people have unearthed lots of fossils of injured trilobites. This hinted that something had attacked them. A. canadensis became a prime suspect.



But Russell Bicknell wasnt so sure. After all, trilobites have hard, thick exoskeletons. And no one had shown that A. canadensis could crack that armor.



Bicknell is a paleobiologist. He works at the American Museum of Natural History in New York City. He was part of a team that set out to learn if A. canadensis really could have crushed and chowed down on trilobites.



This is a closeup of an A. canadensis fossil. It was found in the Burgess Shale of Canada. The fossil shows the creatures head and curled front appendages.Allison Daley


Pinning softies with its spikes



The researchers compared the ancient creatures bendy appendages to those of modern arthropods. These animals include todays insects, spiders and crustaceans. Bicknells team also built computer models of the limbs on A. canadensis. Using those models, the team tested the limbs toughness, range of motion and best swimming position.



The ancient spiky limbs would have been good at grabbing prey. In that way, A. canadensis may have hunted much like todays whip spiders. But the limbs of A. canadensis probably were too fragile to attack armored prey. Those would have included trilobites.





Plus, A. canadensis would have moved most efficiently when its appendages were stretched out front. (Think of how Superman holds his arms while in flight.)



Together, these results suggest that A. canadensis was best suited for chasing soft creatures swimming through the water. It would have snagged prey in its spiky clutches, Bicknell says. It was going to absolutely pincushion something soft and squishy.

The SouthernTropical Andes, which comprisesareasof Ecuador, Peru, and Bolivia, is one of the world's most biodiverse regions especially when it comes to amphibians. The areais home to about980amphibianspecies, including over half of the 150-knownglass frog species. Now, two new membersof the tiny frogs have joined thisever-growing list.

Thecountdown tothe 2020 Summer Gameshas begun. On July 23, 2021, about 11,000 athletes from 206 countries will gather at the Olympic Stadium in Tokyo, Japan, for the opening ceremony of the Games of the XXXII Olympiad.Here are a few contestantsto keep an eye on at the world's mostprestigious sporting event.

All known stars are made of ordinary matter. But astronomers havent completely ruled out that some could be made of antimatter.



Antimatter is the oppositely charged alter-ego of normal matter. For instance, electrons have antimatter twins called positrons. Where electrons have negative electric charge, positrons have positive charge. Physicists think the universe was born with equal amounts of matter and antimatter. Now the cosmos appears to have almost no antimatter.



Space-station data have recently cast doubt on this idea of a practically antimatter-free universe. One instrument might have seen bits of antihelium atoms in space. Those observations have to be confirmed. But if they are, that antimatter could have been shed by antimatter stars. That is, antistars.



Explainer: What are black holes?





Intrigued by this idea, some researchers went hunting for potential antistars. The team knew that matter and antimatter annihilate each other when they meet. That could happen when normal matter from interstellar space falls onto an antistar. This type of particle annihilation gives off gamma rays with certain wavelengths. So the team looked for those wavelengths in data from the Fermi Gamma-ray Space Telescope.



And they found them.



Fourteen spots in the sky gave off the gamma rays expected from matter-antimatter annihilation events. Those spots did not look like other known gamma-ray sources such as spinning neutron stars or black holes. That was further evidence that the sources could be antistars. Researchers reported their find online April 20 in Physical Review D.



Rare or possibly hiding?



The team then estimated how many antistars could exist near our solar system. Those estimates depended on where antistars would most likely be found, if they truly existed.



Any in the disk of our galaxy would be surrounded by lots of normal matter. That could cause them to emit lots of gamma rays. So they should be easy to spot. But the researchers only found 14 candidates.



That implies that antistars are rare. How rare? Perhaps only one antistar would exist for every 400,000 normal stars.



Understanding light and other forms of energy on the move



Antistars could exist, however, outside the Milky Ways disk. There, they would have less chance to interact with normal matter. They also should emit fewer gamma rays in this more isolated environment. And that would make them harder to find. But in that scenario, one antistar could lurk among every 10 normal stars.



Antistars are still only hypothetical. In fact, proving any object is an antistar could be nearly impossible. Why? Because antistars are expected to look almost identical to normal stars, explains Simon Dupourqu. Hes an astrophysicist in Toulouse, France. He works at the Institute of Research in Astrophysics and Planetology.





It would be much easier to prove the candidates found so far are not antistars, he says. Astronomers could watch how gamma rays from the candidates change over time. Those changes might hint at whether these objects are really spinning neutron stars. Other types of radiation from the objects might point to their actually being black holes.



If antistars exist, that would be a major blow for our understanding of the universe. So concludes Pierre Salati, who wasnt involved in the work. This astrophysicist works at the Annecy-le-Vieux Laboratory of Theoretical Physics in France. Seeing antistars would mean that not all of the universes antimatter was lost. Instead, some would have survived in isolated pockets of space.



But antistars probably could not make up for all the universes missing antimatter. At least, thats what Julian Heeck thinks. A physicist at the University of Virginia in Charlottesville, he too did not take part in the study. And, he adds, you would still need an explanation for why matter overall dominates over antimatter.

Excavations in an Israeli sinkhole have turned up a previously unknown Stone Age group of hominids. Its members contributed to the evolution of our genus, Homo. Remains at the new site, known as Nesher Ramla, come from 140,000 to 120,000 years ago. This hominid joins Neandertals and Denisovans as a third Euro-Asian population that belong to our genus. Over time, researchers say, they culturally mingled with and possibly interbred with our species, Homo sapiens.



Hominid fossils also have been found in three Israeli caves. Some date to as early as 420,000 years ago. They likely come from an ancient population of the hominid group whose remains have just turned up at Nesher Ramla. Thats the conclusion of a new study. Paleoanthropologist Israel Hershkovitz led that study. He works at Tel Aviv University in Israel.



Scientists Say: Hominid



His team hasnt assigned a species name to the newfound hominids. The researchers simply refer to them as Nesher Ramla Homo. These folk lived in the Middle Pleistocene. It ran from about 789,000 to 130,000 years ago. Back then, interbreeding and cultural mixing took place among Homo groups. This happened so much, the team notes, that it prevented the evolution of a distinct Nesher Ramla species.





Two studies in the June 25 Science describe the new fossils. Hershkovitz led one team that described the hominid remains. Archaeologist Yossi Zaidner of the Hebrew University of Jerusalem led a second team. It dated rock tools found at the site.



The new fossils further complicate the human family tree. That tree has grown more complex in the past six years or so. Its branches hold several newly identified hominids. They include H. naledi from South Africa and the proposed H. luzonensis from the Philippines.



Nesher Ramla Homo was one of the last survivors of an ancient group of [hominids] that contributed to the evolution of European Neandertals and East Asian Homo populations, Hershkovitz says.





Lots of cultural mixing



Work at Nesher Ramla uncovered five pieces of a skull. They come from the braincase. (As the term implies, this bone encased the brain.) A nearly complete lower jaw also turned up. It still held a lone, molar tooth. These fossils in some ways look like Neandertals. In other ways, they better resemble remains of a pre-Neandertal species. It was called Homo heidelbergensis. Scientists think those individuals occupied parts of Africa, Europe and possibly East Asia as early as 700,000 years ago.



Some Homo fossils from sites in China also show a mix of traits that resemble features of the Nesher Ramla fossils, Hershkovitz says. It may be, he says, that ancient Homo groups with roots at this site may have reached East Asia and mated with hominids there.



But Nesher Ramla folk didnt have to go that far to interact with other hominids. Stone tools at the Nesher Ramla site match those of about the same age made by nearby H. sapiens. Nesher Ramla Homo and early members of our species must have exchanged skills on how to make stone tools, Hershkovitz concludes. These folk also may have interbred. DNA from the new fossils might have confirmed that. For now, however, efforts to get DNA from the Nesher Ramla fossils have failed.



Along with the new fossils, Hershkovitzs team dug up some 6,000 stone artifacts. They also found several thousand bones. Those came from gazelles, horses, tortoises and more. Some of those bones showed stone-tool marks. That would suggest the animals had been butchered for meat.



These stone tools were made by an ancient population in the Middle East. Those individuals belonged to our genus, Homo. The tools resemble those made around the same time by nearby H. sapiens. This suggests the two groups had close contacts.Tal Rogovski



John Hawks at the University of WisconsinMadison did not take part in the new research. But as a paleoanthropologist, hes familiar with ancient hominids and artifacts from their time. Hawks is intrigued that stone tools usually linked with our species turned up among such distinctive-looking non-human fossils. Thats not a smoking gun proving there were close interactions between Nesher Ramla Homo and [our species], he says. But, he adds, it does suggest that.



The Nesher Ramla fossils fit a scenario in which the Homo genus evolved as part of a community of closely related Middle Pleistocene folk. These would have included Neandertals, Denisovans and H. sapiens. Groups at southern sites moved into much of Europe and Asia during relatively warm, wet times, writes Marta Mirazn Lahr. Shes a paleoanthropologist at the University of Cambridge in England. She wrote a commentary that accompanied the two new studies.



Lahr says it appears that ancient groups interbred, became fragmented, died out or recombined with other Homo groups along the way. All of this social mixing, she says, may help explain the wide variety of skeletal looks seen in European and East Asian fossils from our genus Homo.

Bacteria can have superpowers. Some flourish in almost any environment. Others can transform toxic materials into harmless sludge. A bacterium called Shewanella oneidensis can do both. But this microbe also has a much rarer superpower: It absorbs and produces electricity. In fact, new research suggests, these bacteria may be able to use energy collected from wind or solar sources to make fuels to run vehicles and more.



I think of these organisms as eating electricity, says Annette Rowe. Shes a microbiologist at the University of Cincinnati in Ohio. Her team has just identified which genes the microbe uses to gobble electricity.



Explainer: Understanding electricity



Electrons are negatively charged particles. A moving stream of them creates an electric current. Scientists already knew that Shewanella can move electrons back and forth across its cell wall. But they didnt know exactly how the microbes controlled their current, Rowe says.





The pathway for getting the electrons in and out of the cell is like a wire, says Rowe. It allows current to flow from the inside to the outside. Reverse the flow, she says, and you can drive electrons into the cell. The cell could then use those electrons to do some other job, such as generate current. Or it could store the energy to use later. Those electrons could later be used to make fuel, for example.



Rowe knew that Shewanellas cellular wire had to be controlled by genes. But which ones?



Buz Barstow was able to help. He is a biological engineer at Cornell University. Its in Ithaca, N.Y. Earlier, he had made a list of nearly 4,000 of this bacteriums genes. That list also included mutations, or changes, in those genes. Rowe tested these mutants to find the genes that made up Shewanella’s cellular “wire.”



Explainer: What are genes?



Within a cell, a gene can deleted. For the new study, Rowe and her colleagues tested groups of bacteria with groups of deleted genes. Their goal: to see which deleted genes allowed the bacteria to pull in electrons. These were likely genes involved in making the cell’s “wire.”



That was no easy task. It was really tricky to look for electron flow and track the electrons, she says. But in time they devised a clever test. They grew the different mutated bacteria on glass covered by a thin metal film. Then they attached a wire to the bacteria. When they sent an electric current through the wire, they could measure how much the bacteria absorbed or added. If electrons didnt flow, the scientists knew the deleted genes must have been the ones needed for electron flow. 



In time, they narrowed in on five such genes that Shewanella apparently uses to absorb electrons. Each gene tells the cell how to make a protein. Some of those proteins likely grab electrons and bring them into the cell. Others may send signals within the cell that guide the process. Still others can likely expel electrons from the cell.





Bacterial biofuels



Scientists see many ways to use electric microbes. One would be to make biofuels. These differ from fossil fuels, such as coal and natural gas. (Fossil fuels are rich in carbon from decayed remains of ancient living things.) Ethanol, which can be made from corn or sugarcane, is a biofuel that can be added to standard gasoline. Cars that run on diesel can be adapted to run on another biofuel. Called biodiesel, it is fuel made from vegetable oil or animal fats.



Biofuels get their carbon from sources like plants or animal wastes. One day, they may even get their carbon with the help of bacteria, says Rowe.



This technician holds a biofuel sample, an alternative to fossil fuels. One day bacteria may be able to supply the power or the carbon needed to unleash a new wave of such renewable fuels.Sue Barrt/Image Source/Getty Images Plus



Shewanella is among bacteria thatcan pluck carbon atoms out of carbon dioxide. They can use it to create other, larger molecules that could be burned as a biofuel. And powered by the electrons it gobbles, Shewanella could keep making these molecules, Rowe says.



Knowing which genes drive the electron-eating could help scientists develop new biofuels, says Rowe. Even better would be if the electrons that feed the bacteria come from wind or solar power. Such sources could power the biofuel-making process without adding warming carbon dioxide to the air.



Elad Noor is an environmental scientist. He works at the Weizmann Institute of Science. Its in Rehovot, Israel. There, hes helping to develop new ways to fix carbon that is, to pull carbon from carbon dioxide to build other chemical compounds. Using bacteria to create biofuels is attractive because the bacteria can regenerate and should be able to repurpose the carbon. Soring energy in bacteria also would be green, he adds. After all, the microbes dont need dangerous metals, as a normal battery would.



However, working with living organisms is complicated, he warns. Biological systems are hard to predict, he says. There are ways to store energy that are much more efficient.



The genes that Rowes team found in Shewanella show up in other bacteria. The group plans to search for others that can store or release electrons. Rowe also wants to try to improve Shewanellas abilities, because these are the organisms we know the most about.

A long string of galaxies appears to form an arc stretching more than 3 billion light-years across the distant universe. If the arc turns out to be real, it would challenge a basic idea about how the cosmos is structured. Its known as the cosmological principle. And it holds that no matter where you look in the universe, on large scales matter will be distributed fairly evenly.



If it now turns out that this is not true as the newfound arc suggests it would overturn cosmology as we know it, said Alexia Lopez on June 7. She spoke at a news conference at a virtual meeting of the American Astronomical Society. It would mean, she said, that our standard model, not to put it too heavily, kind of falls through.



As a cosmologist, Lopez studies the origins and evolution of the universe. She works at the University of Central Lancashire in Preston, England. She was part of a team that discovered the distant structure. They call it simply the Giant Arc.



Astronomers discovered what they say is a giant arc of galaxies (smile-shaped curve in the middle of this image) by using the light from distant quasars (blue dots) to map out where in the sky that light got absorbed by magnesium atoms in the halos (dark spots) that surround foreground galaxies.A. Lopez



The arc turned up as the researchers were studying images captured as part of the Sloan Digital Sky Survey. That survey, which covers about one-third of the sky, includes the most detailed three-dimensional maps of our universe. It includes light spectra for more than three million astronomical objects.



Lopezs team focused on light from some 40,000 quasars. These are the glowing cores of giant galaxies. Yet they are so distant they appear as mere points of light. On its way to Earth, some of that light gets absorbed by atoms in and around galaxies nearer to us. This absorption creates a signature change in the light that eventually reaches telescopes on Earth or in space.





The Giant Arcs signature is due to magnesium atoms. Each has lost one electron. Theyre glowing in the halos of galaxies about 9.2 billion light-years away. Quasar light absorbed by those atoms traces out a nearly symmetrical curve. That curve contains dozens of galaxies. Lopez reports that together they span about one-fifteenth the radius of the observable universe.



That arc is invisible to the human eye. But if you could see it from Earth, it would span about 20 times the width of the full moon.





See nearly 400,000 galaxies in this animation, which contains images of the actual galaxies in these positions (or sometimes their near cousins). It was made from data derived from release 7 of the Sloan Digital Sky Survey (SDSS). The animations come from Miguel Aragon and Alex Szalay of Johns Hopkins University and Mark Subbarao of Chicagos Adler Planetarium.



The arc as cosmic dilemma



The problem is that this arc makes part of the sky seem too organized. The galaxies are not as evenly distributed as astronomers have always thought they should be.



As such, this finding is a very fundamental test of the hypothesis that the universe is homogeneous on large scales, says Subir Sarkar. Hes an astrophysicist at the University of Oxford in England. Although he studies large-scale structures in the cosmos, he did not take part in the new work. If the Giant Arc is real, he says, this is a very big deal.



But not all researchers are convinced the arc is real. Our eye has a tendency to pick up patterns, Sarkar notes. For instance, he points out that some people have claimed to see Stephen Hawkings initials written in fluctuations of the background cosmic microwave radiation. This is the oldest light in the universe.





Lopez ran three mathematical tests to figure out the odds that galaxies would line up in a giant arc just by chance. All three suggest that the structure is real. One test surpassed physicists gold standard that the odds of it being a statistical fluke should be less than 0.00003 percent.



That sounds pretty good, but it may not be good enough, Sarkar says. Right now, he says, I would say the evidence is tantalizing, but not yet compelling. 



More observations may be needed to firmly support or refute the presence of a Giant Arc.



Explainer: Stars and their families



But if the Giant Arc is real, it would join a growing group of large-scale structures in the universe that, when taken together, break the standard model of cosmology. This model assumes that when you look at large enough volumes of space above about 1 billion light-years across matter will map out evenly. The Giant Arc, however, appears about three times as long as that threshold.



And its not the only such seeming anomaly. There are a number of other large structures in the sky. These include the Sloan Great Wall, the Giant Gamma-Ray Burst Ring and the Huge Large Quasar Group.



With one large-scale structure, that could just be a statistical fluke, Lopez says. Thats not the problem. All of [those big structures] combined is what makes the problem even bigger.

Dont watch TV close to bedtime. Put away your phone, too, or you may have trouble falling asleep. You may not realize it, but the blue light from device screens and even common lamps will confuse your brains internal 24-hour clock. Even white light contains these blue wavelengths. And when blue light enters the eyes, your brain gets the message that it needs to stay awake. But a new type of lighting appears to get around these sleep-challenging effects so you can nod off easily at bedtime.



This new light-emitting diode, or LED, might someday deliver the glow in lamps and other types of home lighting, its developers say. It might even find use in TV, laptop and smartphone screens, says Jakoah Brgoch. Hes a chemist at the University of Houston, Texas. He also helped design the new lighting technology.



He and fellow University of Houston chemist Shruti Hariyani have been studying the properties of phosphors. These substances glow when hit with light.



Explainer: Our bodies internal clocks





Light shines through the lens of an LED, usually a plastic bulb. Behind the scenes is an LED chip, which has small light-emitting diodes attached to a printed circuit board. When the chip is coated with powdered phosphors, the color of the light shining through the lens changes. The Houston team created a new phosphor to make their LED shine with a warm white light. Here, warm means the light contains less of the short, blue wavelengths that can mess with sleep.



Those same blue wavelengths are found in sunlight. And they tell your internal body clock that its time to be awake. Normally that body clock winds down as daylight fades. Melatonin is a hormone produced at night. It helps bring on sleep unless blue light tells your body otherwise. Blue light suppresses the melatonin hormone.



Explainer: What is a hormone?



And our bodies may well get confused if its late and our eyes remain bathed in blue light from devices or indoor lighting. Even though your body craves sleep, its still getting that signal for wakefulness.



Most modern screens and lighting systems use blue LEDs. They are energy efficient, long-lasting and cost little. But, Hariyani says, you have to be okay with the negative side effects [of their light] or fix it.



Shes part of a team thats choosing to fix it.





How to lose the blues



A new violet LED, shown here in a drawing, uses red, green and blue-emitting phosphors to combine the colors of the visible spectrum and create white light.S. Hariyani/University of Houston



Software helps some devices emit less blue light. For example, the iPhones night mode shifts its color palette. But this makes images look more red than normal, so users give up color quality. Plus, the LEDs in this and other smartphones still emit enough blue light to affect the bodys internal clock and melatonin production. People can block out some blue light by wearing yellow glasses near bedtime. However, this too will distort the hues in whatever youre viewing.



Says Brgoch, We wanted to know: Can we get to a high-quality light bulb with warmer and better quality light?



LEDs create white light by mixing red, green and blue hues. While these same primary colors of pigment in paint or crayons mix to make black, light works the opposite way. The white light shining out of an LED comes from the bulb color plus the colors of the phosphors used to coat the LED. Common house lighting uses blue LEDs coated with phosphors whose colors add to the LEDs colors to make white light.



A rarer type of LED has a violet bulb. Places such as museums and clothing stores install white lighting made using violet LEDs. Thats because these are designed to show an object’s true color better than the more common bluer LEDs used in most home lights. One drawback is that violet LEDs cost more. Still, Brgoch and Hariyani chose them for their prototype to get the best color.



Used in the new light, this phosphor glows blue when lit with a violet LED.S. Hariyani and J. Brgoch/University of Houston



To reduce their LEDs blue emissions, the chemists first altered a white powdered crystal that didnt glow on its own. They added a bright silver-colored element to the powders structure. This europium turns the crystal into a phosphor. Europium often is added to lighting phosphors because it helps boost the blue part of an LEDs glow. In this case, it made a true, high-quality blue good for use in an LED. That blue can combine with other colors to make white light.



The Houston team tested the new phosphor to make sure it wouldnt break down easily. They exposed it to heat and water. Not only did the phosphor continue to glow at the same intensity, but its color remained steady. Having all of these properties at once makes it superior to many other phosphors, Hariyani says.



Then they mixed the blue phosphor with red and green ones to create white light. The chemists added this combination to a modified violet LED. Compared to standard violet LEDs, this new one emits far less intense blue light.



Good white and good night?



A mixture of the new blue phosphor, together with red- and green-emitting ones, produces this warm white light when lit by a violet LED.S. Hariyani and J. Brgoch/University of Houston



Theres maybe a dozen phosphors used around the world in lightbulbs, notes Brgoch. To find something new thats on par with what you can buy is fantastic. And, he adds, its lower production of short, blue wavelengths should reduce its effect on someones nighttime secretion of melatonin.



But other aspects of light also influence the body, warns Mariana Figueiro. Her work at Mount Sinai Hospital in New York City focuses on how light affects the body clock and melatonin.



Brightness and colors of light other than blue such as green and yellow also affect the bodys natural readiness for sleep, Figueiro notes. To leave nighttime melatonin alone, she explains, A light source needs to have both low light levels and less blue light. She wonders if everyday lamps and screens could be dim enough not to interfere with the body’s internal clock and still be bright enough for practical use. Still, she says, its certainly worth studying.



To know if the new LED could help people who want to sleep better, scientists will have to measure its effect on melatonin.



This is science that is still relatively new to us, Brgoch says. As such, he says it will take some time for scientists to fully understand how to use the new LEDs in household items.



He and Hariyani shared their findings April 14 in ACS Applied Materials and Interfaces.

E. Toby Kiers rarely wore shoes as a kid. She loved the feeling of soil between her toes. I always felt like something was under there, something secret and hidden, she says.



Now, as an adult, shes revealing that hidden world. Its a tangled network of fungus and plant roots. They all trade resources and even messages. People walk over this network all the time without even realizing its there. Yet understanding its mysteries could help us better cope with Earths changing climate.



Its pretty much the last frontier in understanding how our planet works, says Kiers. She studies fungal networks as an evolutionary biologist at Free University Amsterdam. Its in the Netherlands.



These are the mushrooms of the honey fungus. Its underground mycelia can grow to massive sizes. One individual that lives in Michigan is around 2,500 years old and has mycelia as heavy as three blue whales!Dan Molter (shroomydan) at Mushroom Observer/Wikimedia Commons (CC BY-SA 3.0)



When you think of fungus, mushrooms may come to mind. But the mushrooms that pop up above ground are temporary. The main body of a typical forest fungus remains underground. It is a vast, branching network of very thin, thread-like structures called mycelia (My-SEE-lee-uh). In just one teaspoon of soil there may be enough of these threads to span 10 kilometers (6.2 miles), writes Merlin Sheldrake in his 2020 book, Entangled Life.



All fungi need carbon to grow. Fungi that form networks may feed on the carbon in decaying wood or dead plant matter. Or they may form relationships with living plants. Some fungal networks grow around root tips, like tiny socks. These are known as EM, short for ectomycorrhizae (EK-toh-my-koh-RYE-zee). Others grow into the cells of plant roots. Known as AM, they have an even longer name: arbuscular mycorrhizae (Ar-BUS-kew-lur MY-koh-RYE-zee).





Plants get carbon from photosynthesis. But to grow, they also need nitrogen and phosphorus. Mycelia can range farther than roots to find these nutrients. So fungi and plants regularly trade with each other to get what they need. Almost all the plants in the world share resources through a network of mycelia. Mostly, plants give carbon and receive nitrogen and phosphorus. But mycelia also distribute carbon among plants and carry messages between them. Its almost like the internet or a highway system.



Suzanne Simard is a forest ecologist in Canada at the University of British Columbia in Vancouver. She was the first to show that trees could exchange carbon through fungal networks in a natural setting. A 1997 news report about that work called this the wood wide web. (Its a play on the world wide web, an early name for the internet.) This isnt a perfect metaphor, however, because a fungal system is alive and has its own agenda. But her work opened peoples eyes to the fact that a forest is a highly interconnected ecosystem.



How do networks of mycelia grow and explore? How do they connect with plants? And can their carbon-trading skills help us cope with climate change? Researchers are just starting to find answers.



This stunningly beautiful animation reveals how fungal networks grow underground. E. Toby Kiers team created the video using data captured as a real network grew in the lab.C. Biost/L. Galvez/S. Spacal



Memory without a brain



A fungus is not a plant. It also is not an animal. It belongs to its own taxonomic kingdom. Though mushrooms remain in one place like plants, mycelia can sense and explore their world. Sheldrake writes, Mycelium is a living, growing investigation. Imagine if you could divide your body in two, each side walking through a different door at the same time, then eventually rejoin with yourself. Mycelia do this. They grow in many directions in search of food. Unsuccessful ventures die off while successful ones thicken and branch further. Mycelia have no brain. Yet they fight with other fungi and with critters that graze on them. They even seem to have a basic form of memory, according to new research by Yu Fukasawa and Lynne Boddy.



At Cardiff University in the United Kingdom, Boddy studies fungi that break down things like wood and dead plants. In the 1980s, she showed how a fungal network searches for food and then re-forms itself after it finds something yummy. Last year, Fukasawa and Boddy tested the memory of a typical fungus that likes to feast on wood. They placed blocks of wood containing this fungus onto trays of soil. Then they let the fungus explore until it found a nearby block of fungus-free wood.



Next, the researchers lifted out the original block and carefully shaved off every bit of mycelia growing from it. They placed it into a new tray, with no new block of wood to discover. As the mycelia in the block began to grow again, they sent out extra threads from the side that had faced food in the past. We did this on lots of different trays and with lots of different sizes of wooden blocks, says Boddy. Almost always, you get much more growth on the side where the new food resource had been.



The fungus had somehow remembered which part of itself had faced toward food in the past. So it sent out more growth in that direction. Boddy thinks that the more researchers look, the more examples of fungal memory they will find.



This is not a mushroom. Monotropa uniflora, often called a ghost pipe, is a plant that cannot make its own food from photosynthesis. It mooches off underground mycelia for all the carbon it needs. The mycelia get that carbon from other plants in the forest.egschiller/iStock/Getty Images Plus



Hoarding and trading



A fungus that networks with living plants doesnt feast on them to get the carbon it needs. It trades. Kierss team in Amsterdam has studied how this works in AM networks. Theyre the ones that grow inside plant root cells. These mycelia regularly move nutrients through the soil. And they seem to do so with the shrewdness of a bartering salesperson.



It isnt easy to watch trading inside those microscopic threads below the ground. So the researchers developed a way to put a chemical tag on phosphorus. They added tiny dots that glow when ultraviolet light strikes them. They can make these dots glow in different colors. This lets them watch how phosphorus moves through a network.



In one 2019 study, Kierss team grew mycelia and carrot roots in small dishes. Some regions in each dish were rich in the nutrient phosphorus. Other areas had little of this fertilizer. The fungus moved phosphorus from the rich area to the poor area. Kiers thinks this happens because plants growing in a nutrient-poor area cant get phosphorus on their own through their roots. So compared to plants growing in a nutrient-rich area, those at a nutrient-poor site will trade more carbon to the mycelia for phosphorus.



In 2020, Kiers showed that mycelia will also hoard nutrients when they are plentiful. This makes those nutrients temporarily unavailable to plant roots. Then, plants have to pay [the mycelia] more carbon to get at it, says Kiers.





It seems like aliens, says E. Toby Kiers. In fact, this video shows nutrients moving through an underground network of thread-like fungus. Similar networks link plants and support ecosystems all around the world.



Invisible messages



Mycelia dont just trade with plants. They also carry their messages. Plants may seem like they sit there doing nothing. In fact, they constantly chat among themselves using chemicals. Anything that makes plants smell nice or have a flavor, thats stuff plants are making, says Kathryn Morris. And theyre most likely making it to kill other things, such as insects or disease-causing microbes, she says. Or they could make it as a signal. Morris is a biologist at Xavier University in Cincinnati, Ohio.



Plants can broadcast scent messages through the air. But they also send some through the soil. Consider when aphids attack a broad bean plant. The besieged plant blasts out chemicals that attract wasps to eat the aphids. A 2013 study showed that a broad bean plant that isnt under attack but that taps into the same fungal network as one that is will also send out these warnings. This happens even when researchers separate the plants with plastic barriers so they cant detect signals floating through the air. This suggests the plants must be sending messages underground.



It may seem like the plant in trouble is helping its neighbor. But maybe not. The plant that hasnt been attacked yet may be eavesdropping to detect when it needs to take action and protect itself. Or perhaps the fungal network carries these messages because this helps the survival of all the plants on which it depends for carbon.



Morriss research with AM networks has shown that plants chemical signals reach much farther through the soil if mycelia are there than when they arent. What she wants to know now is how this happens. How do the mycelia broadcast messages? We really dont know, says Morris. Her team is working on a method that will detect where chemicals are and how they move through fungal networks.





Yummy carbon



For a fungus, the whole point of networking with plants is to get the carbon it needs to grow. Plants get their carbon from the atmosphere. They take up carbon-dioxide gas during photosynthesis. Then they turn it into carbon-based sugars that they use to grow. Along the way, those plants will trade some of their sugars with fungi.



The globe is warming, in part, because of all the greenhouse gases that human activities spew into the air as we power our cars, electricity-generating plants, electronics and other machines. Carbon dioxide is the most common greenhouse gas. As you may already know, planting trees and boosting the health of forests can help suck extra carbon dioxide out of the air.



EM fungi form fuzzy socks around plant roots. You can sometimes see them if you look closely at roots (see upper image). Andy Taylor



But not all forests do equal work when it comes to combating climate change. The types of trees and the types of fungi that these trees communicate with can make a big difference in how much carbon a forest absorbs.



The AM fungal networks that Kiers and Morris study are by far the most common type in the world. They are ancient, says Kabir Peay. He is a biologist at Stanford University in California. These networks evolved some 500 million years ago. The mycelia in them tend to network with only one or a few trees or other plants at a time.



EM networks the type that form tiny socks around plant roots are newer. Some EM fungi can decompose dead wood or plants or network with living plants. EM networks tend to be larger and more interconnected than the AM types. Trees also find them more expensive, says Peay. By that he means they charge trees higher prices for nutrients. To make those payments, trees that trade with EM mycelia tend to absorb more carbon from the air, says Peay.



New lab research looked at how much carbon European beech trees take in when connected to an EM network. Bruna Imai is a PhD student in microbiology at the University of Vienna in Austria. After venturing into a nearby forest to collect tree seedlings, she set up pairs of baby trees in her lab. She let an EM network grow to connect some pairs. She kept other pairs from linking up.



To measure the amount of carbon the trees absorbed during the experiment, she exposed them to a special form of carbon that isnt common in nature. She found that plants that were connected to a fungal network took in nearly twice as much carbon dioxide as did plants not connected to any network. This would suggest those fungal networks can play a role in slowing climate change.



A world map of fungi



Fungal networks could be an important ally in the fight against climate change. Thats the goal, says Kiers. But first, researchers need to learn more about the complex sharing of resources and messages underfoot. Trillions of tiny worms, amoebas and microbes live in soil. Hundreds of thousands of fungal species live there, too. All of these species interact with plants and move carbon around. And they do this in ways we dont fully understand right now, says Peay at Stanford.



Explainer: What is a computer model?



Researchers also need to map fungal networks. In 2019, Peay and his team decided to start on this. Another group had already done a global tree survey. It had counted 3 trillion trees. Those data came from hundreds of researchers who went out into forests to identify individual trees and estimate their total across the planet.



Peays team wrote a computer program that looked at the mix of tree species tallied and the climate in each forest. Then it determined what type of fungal network would most likely thrive there. The result was the first world map showing where EM and AM fungal networks likely dominate. AM networks tend to prefer warm, tropical areas. EM networks prefer colder forests.



A pine forest (left) hosts mainly EM fungal networks while a tropical forest (right) hosts mostly AM networks. EM fungal networks can store higher amounts of carbon. But both types of forest store more carbon than soil in a city, farm or pasture.Kabir Peay



As Earths climate warms, forests filled with AM fungi could take over areas that are currently filled with EM fungi. Then those forests would trap even less carbon dioxide than they do now. Peay says that many EM forests are already on the edge of this sort of transformation. Plus, most land used for farming and grazing ends up with poor soil that lacks healthy fungal networks. It end up releasing carbon rather than trapping it.



Peays study didnt directly confirm the presence of particular types of fungal networks under the soil across the globe. In 2021, Kiers launched a new organization called SPUN (The Society for the Protection of Underground Networks) to take that next step. She calls it an underground climate movement.



Its goal is to protect fungal networks and use them to help heal ecosystems. It also runs a youth group called SPUN Youth (@spun.youth on Instagram and TikTok). Eventually, teens will be able to get involved. Theyll be asked to help identify fungal networks in the natural areas near their homes.



When the protection of nature only focuses on plants and animals above the ground, says Kiers, were missing half of the picture. There are ecosystems not being saved because we cant see them, she says.



She hopes that as people learn more about the living world beneath our feet, they will care more about protecting the fungal species that help trees, plants and even people thrive.

A tiny mantis shrimp found off the Pacific coast of South and Central America has inspired a new robot that somersaults and rolls as well as a circus acrobat or Disney sidekick.





Forty years ago, Roy Caldwell documented the somersaulting mantis shrimp in his lab.Credit: Roy Caldwell



Wen-Bo Li is a mechanical engineer exploring how to design soft robots that move by rolling. He works at Shanghai Jiao Tong University in China. Not long ago, he came across a description from more than 40 years ago of how a mantis shrimp navigated beaches.



Roy Caldwell is an ecologist at the University of California, Berkeley. Back in 1979, he published a report in Nature about a mantis shrimp known as Nannosquilla decemspinosa. The tiny crustacean looks a bit like a cross between a caterpillar and a lobster. Caldwell watched as the animal walked underwater. But when waves pulled back, beaching the critter on wet sand, it no longer used its legs. The animal continues in a series of backward somersaults, generally moving in a straight line until it encounters an obstacle or water suffiently deep for swimming, or until it becomes fatigued,” he wrote. He described this as a unique form of locomotion.





Intrigued, Li searched for more detailed information. I found that it could move by a series of backward somersaults for as far as 2 meters [79 inches]. Along the way, it might do 20 to 40 consecutive, dynamic rolls, he learned. It can even mount an incline.





Wen-Bo Li used video footage to analyze the movement of his teams novel robot.Credit: Wen-Bo Li



His team set to work. “After figuring out this fascinating mechanism, Li says, we started to design a soft robot to emulate the somersaulting.” They made the robots body in a series of segments, similar to those in a mantis shrimp. We used 11 chambers. The shape is the same as the flat dorsal [backside] surface of the animal. That makes it stable.



Before it moves, the robot called SomBot stretches out straight. Suction-cup action holds it to the floor. As the researchers push air through long thin tubes attached to one end, the suction releases. This causes the robots torso to bend into a circle and roll.



SomBot can roll pretty quickly up to 9.2 body lengths per second. Li says that the suction combined with the somersault is the key to that speed. With the help of the controllable anchoring, the curling body can be converted into fast movement, he says.



The team described its design in the April 2021 issue of IEEE Xplore.



The rolled-up shape of the ocean dwelling N. decemspinosa (left) and the soft-robot SomBot (right) look similar. Inspired by the mantis shrimp, engineers built their segmented soft robot to scoot faster than other soft robots.R. Caldwell; W.-B. Li



Soft versus hard robots



Daniela Rus is a robotics engineer at the Massachusetts Institute of Technology in Cambridge. She designed a soft-fish robot called SoFi. Hard-bodied robots are made of materials such as hard plastics and metal, she notes. Often large and heavy, these can be dangerous to be around, she explains. Thats why many robot designers prefer softer materials. These robots will end up closer to real organisms in softness.



Engineers often choose soft robots for missions where they need to protect soft organisms around them such as people or other animals. Rus says that this new tech would not only be safer but also more capable of a wide range of motions than hard-bodied robots.



For its new robot, the Shanghai team used an elastomer. Its a polymer a material made from a long chain of repeating units. The same rubbery elastomer is sometimes used in shoe soles and car tires. After molded into a desired shape, it stays elastic. Rus describes this as being compliant. That flexibility, she says, should allow it to withstand force and to move as needed.





A need for speed



Lis group had started with one big goal: make SomBot faster than earlier types of soft robots. Its somersaulting action appears to have helped them succeed. The team tested SomBots speed against a rigid-but-soft robot inspired by a cheetahs spine. That soft-rolling robot looks like a caterpillar. It was designed to move much like human fingers. SomBot beat it by more than three body lengths per second.



But while SomBots speed is impressive, Li and his team have not yet gotten full control of its rolling action. They are beginning to consider giving it a closed-loop design. This may be something like a doughnut or perhaps the mythical snake that bites its own tail.



SomBots suction also works best on smooth surfaces. However, most natural ones are fairly coarse. “Anchoring by suction won’t work on rough and uneven surfaces,” such as sidewalks, Li admits.



The new robots style of moving is something that Disneys animators appreciate, too. In their new animated film, Raya and the Last Dragon, the sidekick who transports the warrior princess also relies on rolling locomotion. One of the movies producers has described that sidekick named Tuk Tuk as part armadillo, part pillbug and part pug (a type of dog). Two of those can roll into a ball. In the movie, Tuk Tuk somersaults across the Asian landscape, speeding Raya from one site to another.

Mention foraging bees, and most people will picture insects flitting from flower to flower in search of nectar. But in the jungles of Central and South America, so-called vulture bees have developed a taste for flesh. Scientists have puzzled over why the stingless buzzers seem to prefer rotting carcasses to nectar. Now one group of researchers thinks it has cracked the riddle. The key came from looking into the bees guts.



Bees are vegetarian, notes Jessica Maccaro, so these ones are a very large exception. In fact, shed go so far as to say these are kind of the weirdos of the bee world. Maccaro is a PhD student in insect biology. She works at the University of California, Riverside.



Laura Figueroa watches as meat-eating bees swarm a piece of rotting chicken in the Costa Rican jungle. Despite being a vegetarian, this PhD student helped string up the meat. She was part of a research team that examined the insects guts.Credit: Q. McFrederick



To study these bees, she worked with a team of scientists who travelled to the Central American nation of Costa Rica. In its jungles, vulture bees usually feed on dead lizards and snakes. But theyre not too picky. These bees will eat any dead animal. So the researchers bought some raw chicken at a grocery. After cutting it up, they suspended the flesh from branches in the trees. To deter ants, they smeared the string it dangled from with petroleum jelly. 





The funny thing is were all vegetarians, says entomologist Quinn McFrederick, who also works at UC-Riverside. Entomologists are scientists who study insects. It was kind of gross for us to cut up the chicken, he recalls. And that gross factor intensified pretty quickly. In the warm, humid jungle, the chicken soon rotted, turning slimy and stinky.



But the bees took the bait within a day. As they stopped by to dine, the researchers trapped some 30 of them in glass vials. The scientists also captured another 30 or so of two other types of local bees. One type feeds just on flowers. Another type dines mostly on flowers but sometimes snacks on rotting meat. Central and South America are home to all three types of these stingless bees.



The bees were stored in alcohol. This immediately killed the insects but preserved their DNA. It also preserved the DNA of any microbes in their guts. This allowed the scientists to identify what types of bacteria they hosted.



Microbes live in the guts of animals, including people. Certain of those bacteria can help break down food. They also can protect animals from some toxin-producing bacteria which often live on rotting meat.



The guts of vulture bees had a lot more of a particular type of bacteria than did vegetarian bees. Those bacteria are similar to ones found in the intestines of vultures and hyenas. Like vulture bees, these animals, too, feed on rotting meat.



Maccaro and her teammates described their new findings November 23 in the journal mBio.





Acid protection against rotten meals



Certain bacteria make the guts of vultures and hyenas very acidic. This is important because acid-producing bacteria kill toxin-producing bacteria in rotting meat. In fact, these microbes keep vultures and hyenas from getting sick. It probably does the same thing for the meat-eating bees, Maccaro and her team now conclude.



The meat-eating bees had between 30 and 35 percent more acid-producing bacteria than the strictly vegetarian bees. Some types of the acid-making microbes showed up only in the meat-eating bees.



Acid-producing bacteria also reside our intestines. The human gut doesnt, however, have as many bacteria as do the guts in vultures, hyenas or meat-eating bees. That may explain why the bacteria on rotting meat can give people diarrhea or make us throw up.



Maccaro says its hard to know which evolved first the gut bacteria or the bees ability to eat meat. But, she adds, its likely the bees turned to meat because there was so much competition for flowers as a food source.



Two types of vulture and a stork dine on a carcass in Kenyas Maasai Mara National Reserve. High levels of acid-making microbes in the gut of such carrion-feeders can kill otherwise sickening bacteria in rotting flesh. Similar acid-making microbes appear to aid meat-eating bees, a new study finds.Anup Shah/Stone/Getty Images Plus



The role of a meaty diet



David Roubik is the evolutionary ecologist who described how meat-eating bees find and devour their meals. He works for the Smithsonian Tropical Research Institute in Panama. Scientists knew the bees were collecting meat, he says. But for a long time, he adds, nobody had the foggiest idea that the bees were actually consuming flesh.



People had thought the bees somehow used it to make their nests.



He showed, however, that they were actually eating flesh, biting into it with their sharp mandibles. He described how once the bees find a dead animal, they deposit a trail of pheromones signaling chemicals on plants along their flight back to the nest. Their nest mates then use these chemical markers to track down the carcass.



A large dead lizard placed 15 meters [about 50 feet] from one nest was located by bees within eight hours, Roubik reported in a 1982 Science paper. It described some of his research in Panama. Groups of 60 to 80 bees removed the skin, he says. After then entering the body, they reduced much of the carcass to a skeleton during the next 2 days.



The bees consume some of the meat for themselves. They regurgitate the rest, storing it in their nest. There it will serve as a food source for developing bees.



The large numbers of acid-loving bacteria in the vulture bees guts end up in this stored food. Otherwise, destructive bacteria would ruin the food and release enough toxins to kill the colony, says Roubik.



Meat-eating bees also make surprisingly good honey by turning partly digested dead animal material into sweet honey-like glucose, observes Roubik. I have tried the honey a number of times, he says. It is sweet and delicious.

For pranksters, there is no better holidaythan April Fools' Day. Celebrated annually on April 1, it is the only day of the year when fun, harmless hoaxesgo unpunished. Themischievous holiday has murky origins. Somebelieve itstarted in 1582when France transitioned from the Julian calendar which began the year around April 1 to the currently usedGregorian calendar. Thoseunaware, or unwilling, to accept thedate change werepranked.Others thinkthe holiday startedas a cheerful way to mark the start of spring.

Donut lovers,rejoice!Friday,June 4, 2021, is National Donut Day. That means it is your civic duty to consume at least one oreven a dozen of the delicious confections. The fun US holiday, observed annually on the first Friday of June,was startedin 1938 by theSalvation Army to help raisefunds forthose in need.

Dr. Madeleine Jana Korbel Albright, the firstfemale US Secretary of State, passed away on March 23, 2022. A statementreleased by her family revealed that the 84-year-oldhad been suffering from cancer.Thehighest-ranking woman in the history of the Americangovernment at the time of her appointment,Dr.Albrightplayed a crucial role in shaping USforeign policy in the 1990s.

Hunting for aliens might sound like science fiction. But it’s a serious science. Alien-seeking researchers don’t chase down UFOs, though. Some use telescopes to listen for messages broadcast by alien civilizations. Others peer at distant words for evidence of life.



No aliens have been found yet. But it’s a big universe. Astronomers have found thousands of planets orbiting other stars. And there may be billions more worlds still to be discovered. Some may even have moons that can support life. That’s a lot of potential alien real estate. Over the last 60 years, astronomers have scoured only a tiny bit of it for interstellar messages. The area searched so far is like a hot tub’s worth of water out of all the world’s oceans.



See all the entries from our Lets Learn About series



Some people think we’d have a better chance of meeting aliens if we introduce ourselves. That is, beam our own messages into space. These messages could be written in mathematical patterns. (Math is thought to be a universal language.) One such message was sent from the Arecibo telescope in Puerto Rico in 1974. But other scientists say this is a bad idea. We might not want to advertise our existence to unfriendly aliens.





There may also be aliens that aren’t able to send or read messages. Some planets may be home to simple, even microscopic life forms. To find those worlds, astronomers look for new worlds in the so-called habitable zone. This is the area around a star where a planet would be just warm enough to have liquid water. That’s important because water is essential for all known life. One such planet may orbit the nearest star to our sun.



A planet may not have to look just like Earth, though, to be a good home for aliens. Some hardy creatures on our own planet thrive in seemingly unlivable conditions. Microbes at the seafloor bask in scalding water. Meanwhile, microbes nestled in Antarctic ice withstand freezing cold. Other critters slurp up toxic chemicals or bathe in acid. Learning about these “extremophiles” broadens our view of what places in the cosmos might be livable.





Microbial aliens might also be found closer to home. Saturn’s moon Enceladus is a good place to look. So is Jupiter’s moon Europa. Both have oceans of liquid water encased in their icy crusts. Mars could even host life in a lake near its south pole. A recent survey suggested that most Americans would welcome finding alien microbes.



The question of whether we are alone in the universe has captured peoples imaginations for millennia. And the answer has two equally mind-blowing possibilities.  In all the vast expanse of outer space, either we are completely alone or we are not.



Want to know more? Weve got some stories to get you started:



Worlds deepest zoo harbors clues to extraterrestrial life Scientists have found a wide range of life deep below Earths surface. Those discoveries could inform the search for life on other planets. (6/15/2017) Readability: 6.6



Only a small fraction of space has been searched for aliens How little? A volume equivalent to a hot tubs worth of the Earths oceans. (10/24/2018) Readability: 8.2



Should we call out to space aliens? To speed up the search for extraterrestrials, some scientists recommend sending signals to space. Others disagree. (3/21/2017) Readability: 8.0





Heres how astronomers can tease out what gases exist in an exoplanets atmosphere and find clues about whether that world might be habitable.



Explore more



Scientists Say: Exomoon



Explainer: What is a planet?



Lets learn about exoplanets



Profile: Looking for life beyond the solar system



Keeping space missions from infecting Earth and other worlds



Finding living Martians just got a bit more believable



Most Americans would welcome a microbial E.T.



Will we know alien life when we see it?



A trail of cosmic dust may lead to alien life



Planets with hydrogen skies could harbor life



Cool Jobs: Reaching out to E.T. is a numbers game



Activities



Word find



The message to alien civilizations sent out by the Arecibo Radio Telescope in 1974 was a picture. It included a basic sketch of a person, the solar system and other information. But in order to beam that picture into space, scientists had to translate it into binary code. Thats a series of 1s and 0s. Learn how to read and create your own binary code messages with this activity from the Rio Tinto Alcan Planetarium in Montreal, Canada.

Mythical mermaids are often known for their fishy tails and alluring songs. But if you were underwater with one, her tunes wouldnt sound quite like they do in the movies. And you might struggle to understand the words as Ariel or her other mermaid friends burst out singing.



Even next to a mermaid, the song would sound muffled and would seem to come from all around, says Jasleen Singh. You could still make out what she is saying, but it would sound fuller with less clarity, Singh says. She studies human hearing at Northwestern University in Evanston, Ill.





If mermaids existed, and if they sang and talked to one another, their hearing and sound-making setups might resemble marine creatures features instead of humans. To understand why, you have to start with the basics of sound and hearing.



Explainer: How the ears work



Sound is produced when an object vibrates. Touch your throat while you talk, and you can feel your vocal cords vibrating inside your neck. These vibrations can travel through gases, liquids and solids. In each medium, atoms and molecules get pushed around by a sound sources back-and-forth motion. These particles bump into each other in a rippling pattern of waves. Like a line of falling dominoes, the colliding particles spread sound.



Human hearing starts with sound waves entering the air-filled space in each earhole. The waves vibrate the eardrum, which wiggles three little ear bones. One of the bones taps on a snail-shaped structure in the inner ear called the cochlea. This fluid-filled structure converts the vibrations into electrical signals that the brain understands as sound.



Underwater, its a different story. Since water plugs your ears, you rely on sound waves directly vibrating the skull. This happens on land too, but it works better below the waters surface. Thats because water and bone have similar densities. When sound waves gently rattle the skull, that is directly stimulating the inner ear the cochlea itself, Singh says. This is called bone conduction. We humans, however, are much more attuned to the sound waves striking our eardrums. As a result, the sound quality of bone conduction is not as good as regular air conduction.



Plus, its difficult to figure out where a sound is coming from underwater. On land, if someone starts talking on your right side, sound waves hit your right ear before your left. This slight variation in timing helps your brain find the source of a sound. But sound travels much faster in water than in air. Thats because the particles that make up liquids are closer together. In water, there is virtually no time difference between sound hitting each ear. That makes underwater noise sound very full, like its coming from everywhere.









Our sea-dwelling relatives



To hear their friends talk and sing properly, mermaids might have evolved hearing structures more like aquatic animals.



Marine mammals, such as whales, dolphins and seals, hear in a way very similar to humans, notes Colleen Reichmuth. A biologist, she studies marine mammals at the University of California, Santa Cruz. These creatures have cochleae. They also have ear bones and eardrums, though not always functional. And they have evolved some adaptations to help them hear under the sea.





The lower jaw of dolphins and some whales contains fat that directs sound to the bony middle ear. This fat has a special chemical composition that makes it really suitable for transmitting acoustic waves, says Laela Sayigh. Shes a marine biologist at Hampshire College in Amherst, Mass., and Woods Hole Oceanographic Institution in Massachusetts.



Some marine mammals, such as seals, have convertible ears. On land, the animals can open ear holes to pick up sound waves traveling through air. But when diving, their ear tissue swells with fluid, plugging the holes. The fluid-filled ears help transfer sound from the water to the cochleae.





Those features could help a mermaid hear her friends songs more clearly. But if mermaid voices were more like those of marine mammals, their vocal systems could get a major upgrade, too.



Whales, dolphins, seals and other marine mammals can sing underwater, creating complex noises with musical notes or rhythms. They produce sound by passing air along tissues to vibrate them, similar to a humans voice box. But unlike people, who must breathe out to make noise, many of these sea creatures dont need to expel air from their mouths or blowholes to produce sound.



Underwater, air is a precious commodity, says Joy Reidenberg. If whales exhaled when using their voices, they would have to keep resurfacing for more air. That would interrupt their lengthy songs, Reidenberg says. She studies animal anatomy at the Icahn School of Medicine at Mount Sinai in New York City.



Instead, whales and dolphins can move air around in their bodies and even reuse it. This air recycling system would certainly help a mermaid sustain conversation or song below the surface, Reichmuth says.



For a voice that really carries, mermaids might be built like baleen whales. These whales, which include humpbacks, have huge vibrating structures in their throats that toss out sound. Some can make noises so loud and low-pitched too low for humans to hear that the songs could potentially travel more than 1,000 kilometers (600 miles) in the ocean. (Lower-pitched sound waves lose less energy when traveling through water than higher-pitched ones.)



Humpback whales sing beautiful, lengthy songs. But they dont need to breathe out of their mouths or blowholes to do it. These whales recycle the air supply in their bodies and can stay submerged for nearly an hour. Craig Lambert/iStock/Getty Images Plus



Something sounds fishy



A mermaids mammal upper half may not be the only part that could make or hear sounds. Crustaceans and fish are known to make quite a ruckus, too. In fact, snapping shrimps, typically around four centimeters (1.5 inches) long, are some of the loudest creatures on Earth. As the name implies, these shrimp snap one of their claws to produce a colossal sound.



Many fish use a similar method to make noise. They click or rub their bodys bony structures together. Sea horses, for example, produce clicks by knocking the tops of their skulls into the horns on their heads. They do this when wooing a mate.



You can think of it like clicking your teeth together, says Audrey Looby. A marine ecologist, she studies fish at the University of Floridas Nature Coast Biological Station in Cedar Key.



Other species can use their muscles to vibrate an internal organ, like playing a drum. Some fish can even communicate by expelling air out their backside, Looby says. Essentially, fish communicating through farting. And they have special cells lining the sides of their bodies that can sense vibrations in the water, helping them to hear.



If you met a mermaid, she might have both fish-like and mammalian structures to communicate with her underwater friends. Motion-detecting cells may line her tail, and her ears may work like a seals to hear both in and out of water. She would probably recycle her bodys air supply to talk and sing without having to keep resurfacing. But her conversations may also be sprinkled with teeth chattering, clapping and even farting.

A massive plume ofdust and sandfrom the Sahara Desert engulfed parts of Europe in mid-March. Storm Celia blew into Spainon March 14, 2022, turningthe skiesinto aneerie rusty orangeand covering the ground and vehicleswith finesand particles. The thick dust layerlingered for several days,causingofficials to issue extremely poor air quality ratings in the capital city of Madrid and acrosslarge parts of Spain'ssoutheast coast.

Savanna (noun, Suh-van-uh)



If you’ve ever seen The Lion King, you’ve seen a savanna. A savanna is a rolling grassland scattered with trees and shrubs. This type of ecosystem covers about 20 percent of the world’s land. That includes nearly half of Africa. The African savanna is home to lions, hyenas, zebras and other Lion King creatures. The Australian savanna hosts animals like kangaroos and wallabies. Savannas are also found in South America and Asia. And in North America, the oak savanna is one of the worlds most endangered ecosystems.



Most people may be familiar with the African savanna. But did you know North America has savannas, too? These grasslands are scattered with oak trees.Steepcone/Wikimedia Commons (CC BY-SA 3.0)



Most savannas don’t have the four seasons you might be familiar with. These areas alternate between dry winters and wet summers. During the winter, a savanna may not get rain for months at a time. That prevents many trees from growing there. Dry conditions also allow savannas to catch fire easily. Those fires prevent young trees from growing up and turning these habitats into forests. But heavy summer rains help thick grasses grow. That prevents the savanna from being a desert.



In a sentence



African savanna elephants are the largest land mammals in the world.



Check out the full list of Scientists Say.

On March 27, 2022, Troy Kotsur becamethe first Deaf male actor to win an Oscar.The 53-year-old, who won Best Supporting Actorfor his portrayal ofFrank Rossi in "CODA," isonly the second Deaf actor to attain the prestigious award. In 1987,Marlee Matlin took home the Best Actress awardfor her role as Sarah in the movie "Children of a Lesser God."

The African Serengeti looks much like it did hundreds of years ago.



Huge herds of wildebeests, over one million strong, still roam the savanna. Lions, hyenas and other top predators stalk the herds. This keeps their prey from eating too much vegetation. Diverse trees and grasses support scores of other species, from vivid green-orange Fischers lovebirds to dung beetles. In turn, such species carry seeds or pollen across the plains, aiding the spread of plants.



Overall, the Serengeti is a prime example of what biologists call an ecologically intact ecosystem. A bustling tangle of relationships work together. This sustains a rich diversity of life. People are there, but represent only a small part of the whole. And they dont disrupt the rest of the system.



Such places are vanishingly rare. Ecosystems on nearly all the Earths land a staggering 97 percent no longer are intact. Thats according to a sweeping new survey of Earths land-based ecosystems. Over the last 500 years, many have lost habitat or species. In others, populations of key animals have shrunk. Just 3 percent of the surveyed lands are unchanged, researchers reported April 15 in Frontiers in Forests and Global Change.



People have damaged forests around the world, destroying habitats and threatening species. This Indonesian rainforest has been cut to build plantations of palm oil, for instance. Photography by Mangiwau/Moment/Getty Images



Even the few remaining intact ecosystems may be at risk. Only about 11 percent of them are within protected areas, the researchers found. Much of the intact land overlaps areas that now are or were historically managed by Indigenous people. Those people often have played a vital role in maintaining healthy ecosystems, the researchers say. One way these habitats could be conserved, many scientists think, would be to make sure that Indigenous communities retain legal rights to manage these lands.



Much of the last pristine habitat exists in the far North. Think Canadas boreal forests or Greenlands icy tundra. Neither are bursting with biodiversity. But chunks of rainforests in the Amazon, Congo and Indonesia still host species-rich ecosystems.





These are the best of the best. The last places on Earth that havent lost a single species that we know of, says Oscar Venter. He works at the University of Northern British Columbia in Prince George, Canada. He is a conservation scientist who did not take part in the new study. Its crucial to identify these ecological gems, he says. Some may be under threat of development. Among those is the Amazon rainforest. Mapping where these largely unaltered sites are is the first step toward protecting them.



Conservation scientists have long tried to map humanitys touch. Previous estimates used data on where people live. Others used images from satellites. Such images can reveal physical changes, such as roads and damaged forests. They even can show indirect effects such as light pollution. In those studies, 20 to 40 percent of the globe appear little changed by people.



But many human effects may not be obvious, notes Andrew Plumptre. He is a conservation biologist at the University of Cambridge in England. Hunting, the impacts of invasive species, climate change, Plumptre notes. These can harm ecosystems. But they cant be easily sensed via satellite. Imagine the Serengeti with fewer lions or hyenas or none at all. It would look the same from space. But it would be missing key species that help the whole ecosystem run.



Plumptre wanted another way to measure the influence of people. He and his colleagues looked for ecosystems that havent changed as human populations have grown and spread. They defined an intact ecosystem as one that has all the same species today and at the same levels as it did in 1500. (The International Union for the Conservation of Nature starts from that year when counting species extinctions. Even long before that, though, people changed nature, such as by wiping out big mammals.)





Where the wild things (still) are



The team combined several types of existing data. They looked for places where habitats seem undisturbed by people. And they used three different measures of where species have been lost. The data covered about 7,500 animal species. Put together, the data showed undisturbed regions that had kept all their critters.



Some wide-ranging species need large swaths of land. So the researchers first looked for areas larger than 10,000 square kilometers (3,900 square miles). (Thats roughly the size of Puerto Rico.) Only 2.9 percent of undisturbed land areas that big still hold all the species they did 500 years ago. Then they looked at smaller areas, of 1,000 square kilometers (390 square miles). That bumped the percentage up just a bit, to 3.4.




Degraded ecosystems



Human activity has effects that reach nearly the whole globe. Many areas have lost species, as color-coded on this map. Based on a survey of about 7,500 animal species, purple areas show the 3 percent of land where no known species have been lost since the year 1500.



Lost species in the wilderness



A.J. Plumptre et al/Frontiers in Forests and Global Change 2021



A.J. Plumptre et al/Frontiers in Forests and Global Change 2021




Theres more to an ecosystem than just whos in it, though. Lower numbers of key species can also throw a system out of whack. The researchers tallied up the population densities of 15 types of large mammals. These included gorillas, bears and lions. Together, the chosen species span much of the globe. Why large mammals? They play important roles in ecosystems, Plumptre explains. The best historical data exist for these. They also are often the first to be affected by human neighbors.



Some of those mammals had declined in places that were otherwise intact. Accounting for dropped the ecologically intact total down to 2.8 percent of all land.



Overall, the tally of intact ecosystems was much lower than we were expecting, Plumptre says. Going in, Id guessed that it would be 8 to 10 percent. It just shows how huge an impact weve had.



Understanding the challenge



Jedediah Brodie is a conservation ecologist at the University of Montana in Missoula. He and Venter both wonder if the study authors were too strict in how they defined intact.



Many ecosystems around the world have lost one or two species but are still vibrant, diverse communities, Brodie says. In such places, a drop in a few species may not spell disaster for the whole ecosystem. Other species may swoop in to fill those roles.



Still, the study is a valuable first look. It shows us where the world looks like it did 500 years ago and gives us something to aim for, Plumptre says. It also identifies areas that could be restored. Adding back up to five lost species could restore 20 percent of land to its former glory, the researchers calculate. 



Reintroducing lost species has worked well in some places. In Yellowstone National Park, bringing back wolves has put the ecosystem back into balance. Such schemes may not work everywhere. But deciding how to protect nature is a growing, global challenge. Plumptre hopes policy makers will take note. Its possible to not just protect the land thats there, but also think about restoring it to what it could be.



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Invasive species can wreak havoc on ecosystems. These organisms settle into and cause harm in places where they arent native. For example, mosquitoes spread diseases. Cats kill birds and some mammals. Many insects chew up crops or kill trees. Such damage can be very costly. So is managing the mayhem they cause. New research suggests that just between from 1970 and 2017, invasive species cost the world at least $1.28 trillion.



By estimating the global cost, we hoped to raise awareness of the issue, Boris Leroy tells Science News. A biogeographer, Leroy studies how life, such as plants and animals, spread across regions. He works at the French National Museum of Natural History in Paris. Researchers have studied invasive species for decades, he says. But many people remain unaware of the problems these eco-bullies cause.



Leroy and his team set out to tally that cost. They scoured research papers for estimated costs of specific invasions. They came up with 1,319 studies to analyze. To find long-term trends in costs of invasions, the researchers used a computer model. It let them account for currencies used in different countries and how the value of money changed over time.







The new study examined costs of dealing with damage plus the cost of managing the species. Damage control cost about $892 billion. Thats 13 times more than the $66 billion spent on such efforts as ousting invaders or controlling their spread. The total yearly cost of invasive creatures doubled roughly every six years between 1970 and 2017. In 2017, that annual bill reached $162.7 billion, the team reports March 31 in Nature.



Scientists Say: Invasive species



Many invaders hitch a ride to new places via cargo ships and planes. So inspecting cargo or monitoring for new pests could help lower the cost of invasions, says ecologist Helen Roy. Its much cheaper than waiting for the species to establish and spread widely before responding, she says. Roy works at the U.K. Centre for Ecology and Hydrology in Wallingford, England. She was not involved with the study.



The new results are likely an underestimate. Thats because research on invasive species doesnt capture the whole problem. For instance, more reports focus on North America and Europe than on whats happening in South America or Africa. And pests that harm crops, such as insects, get more attention than do invasive plants. However, Roy notes, the study does show that invasive species are a massive problem thats getting worse.




Costly critters



Researchers analyzed papers from the past few decades to pin down the most expensive invaders. This bar graph shows the results. Total costs for each species are broken down into three categories: damages, costs for managing the species and mixed costs. Mixed costs dont fit neatly into either damage or management costs.    



The top 10 costliest invasive species, 19702017



E. Otwell



E. Otwell



Source: C. Diagne et al/Nature 2021




Data Dive:



What was the cost of the most expensive invasive species?



Look at the different colors making up that first bar. Roughly how much of the total cost is due to damage? How much of the cost is due to management?



Which three invasive species have cost the most damage? What is the total damage cost of these three creatures?



Which invasive species has the highest management cost?



How many of the 10 costliest invaders are insects? How many are mammals? How many are reptiles?



Choose one of the species. What kinds of damage can this creature cause? How might this animal affect other wildlife? How might it affect people? How might this animal affect crops or buildings?



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Objective: To measure the effect of temperature on the rate of a chemical reaction



Areas of science: Chemistry, science with your smartphone



Difficulty: Easy intermediate



Time required: 25 days



Prerequisites: None



Material availability: Readily available



Cost: Very low (under $20)



Safety: Adult supervision may be needed when working with hot water solutions



Credits: Andrew Olson, PhD, Science Buddies; edited by Svenja Lohner, PhD, Science Buddies






You may have seen a television commercial for Alka-Seltzer tablets or heard one of their advertising slogans: Plop, plop, fizz, fizz, oh what a relief it is! When you drop the tablets in water, they make a lot of bubbles, like an extra-fizzy soda, as shown in the main image up top (Figure 1). And like a soda, the bubbles are carbon dioxide gas (CO2). However, with Alka-Seltzer, the CO2 is produced by a chemical reaction that occurs when the tablets dissolve in water.





Alka-Seltzer is a medical drug that works as a pain reliever and an antacid (antacids help neutralize stomach acidity, such as heartburn). The pain reliever used is aspirin and the antacid used is baking soda (sodium bicarbonate, NaHCO3). To take the tablets, they should be fully dissolved in a glass of water. When sodium bicarbonate dissolves in water, it dissociates (splits apart) into sodium (Na+) and bicarbonate (HCO3) ions. (An ion is a molecule that has a charge, either positive or negative.) The bicarbonate reacts with hydrogen ions (H+) from citric acid (another ingredient in the tablets) to form carbon dioxide gas and water. In other words, carbon dioxide gas is a product of this reaction. The reaction is described by Equation 1 below:



Equation 1.3HCO3 + 3H+ 3H2O + 3CO2



So how is temperature related to this bicarbonate reaction? In order for the reaction shown above to occur, the bicarbonate ions have to come into contact with the hydrogen ions. Molecules in a solution are in constant motion and are constantly colliding with one another. The hydrogen and bicarbonate ions must collide at the right angle and with enough energy for the reaction to occur. The temperature of a solution is a measure of the average motion (kinetic energy) of the molecules in the solution. The higher the temperature, the faster the molecules are moving. What effect do you think temperature will have on the speed, or rate, of the bicarbonate reaction?



In this chemistry science project, you will find out for yourself by plopping Alka-Seltzer tablets into water at different temperatures and measuring how long it takes for the chemical reaction to go to completion. In addition, you can record the sound of the Alka-Seltzer fizzle using a smartphone equipped with a sensor app. Do you think it will fizz more loudly in hot or cold water?



Terms and Concepts




Chemical reaction



Alka-Seltzer



Baking soda, or sodium bicarbonate



Molecule



Products



Temperature



Bicarbonate reaction



Reaction rate




Questions




What is the bicarbonate reaction? What are its products?



Keeping in mind that an increase in temperature reflects an increase in the average molecular motion, how do you think increasing temperature will affect the reaction rate?



What temperature change do you think would be required to increase, or decrease, the reaction time by a factor of two?



What other factors besides temperature can affect how well a chemical reaction takes place?




Materials and Equipment




Alka-Seltzer tablets (at least 12; if you plan to do additional variations to the project, you will want to get a larger box)



Thermometer with a range of at least 0C to 60C (32F to 140F)

A suitable thermometer is available from Amazon.com



A standard kitchen candy thermometer will also work fine





Clear drinking glasses or jars; about 8 ounces, or 240 milliliters (two of the same size)



Graduated cylinder, 100 mL. A 100 mL graduated cylinder is available from Amazon.com. Alternatively, measuring cups may be used.



Masking tape



Hot and cold tap water



Ice



With option 2 in procedure: Stopwatch or a clock or watch with a second hand



Optional: A helper



Lab notebook



Pencil



With option 1 in procedure: Smartphone with a sensor app such as phyphox, available for free on Google Play for Android devices (version 4.0 or newer) or from the App Store for iOS devices (iOS 9.0 or newer).



With option 1 in procedure: Small sealable (waterproof) plastic bag that fits your phone inside of it




ConditionTemperature(C)Reaction Time(s)Optional: Maximum Sound Intensity(dB)Trial #1Trial #2Trial #3AverageTrial #1Trial #2Trial #3AverageHot Tap Water         Cold Tap Water         Ice Water         Table 1. In your lab notebook, make a data table like this one. You will record your results in it.



Experimental Procedure



Note: In this science project, you will investigate how water temperature affects the dissolving time of an Alka-Seltzer tablet. You will use a smartphone equipped with a sensor app to record the fizzing sound of the Alka-Seltzer reaction in water and measure the time it takes for one Alka-Seltzer tablet to react completely in water. The app creates a graph that will not only give you information about the reaction time but will also allow you to assess how loud each reaction was based on the measured sound intensities. If you do not have a phone, you can observe the reaction and use a stopwatch to time how long it takes for each tablet to dissolve.



Figure 2. Mark your glass on the outside with masking tape to indicate a water level up to about 1 inch below the rim.M. Temming



Do your background research and make sure that you are familiar with the terms and concepts in the Background.



In your lab notebook, make a data table like Table 1. You will record your results in this data table.



Prepare a drinking glass so that it is marked at the 200 mL point. You will use the same glass for multiple trials, so it is convenient to mark the desired water level. Note: If your glass fits more than 8 ounces, make a mark about 1 inch below the rim.

Add 200 mL (a little less than 1 cup) of water to the drinking glass, or fill it up to about 1 inch below the rim.



Use a piece of masking tape on the outside of the glass to mark the water level, placing the tape with its top edge even with the water level in the glass, as shown in Figure 2.



Note: You do not want to fill the glass completely full because the bicarbonate reaction produces bubbles that could splash out.





You will fill the drinking glass with the same volume of water at three different temperatures: hot tap water, cold tap water and ice water.

For the hot and cold tap water, run the water until the temperature stabilizes. Fill the glass with water to the level of the masking tape. Be careful when handling the hot water.



For ice water, fill the glass about half full with ice cubes, then add cold tap water to a bit above the level of the masking tape. Stir for a minute or two so that the temperature equilibrates. Once temperature has equilibrated, remove the ice cubes from the water’s surface using a spoon or other utensil immediately before adding the Alka-Seltzer tablet. (Pour out any extra water so that the water is up to the level of the masking tape.)





Prepare the drinking glass with one of the three temperatures as described in step 4. Then measure the reaction time for that temperature either by following option 1 (sensor app), described in step 6, or option 2 (stopwatch), described in step 7.

If you use the phyphox app to measure the amplitude of sounds, you will need to calibrate the sensor first to get correct decibel readings on your device. The sensor has to be recalibrated between individual recordings. Instructions on how to do the phyphox sound sensor calibration are provided in the video above.



Option 1: Using the Sensor AppSensor apps such as phyphox let you record data using sensors that are built into many smartphones, including a microphone that you can use to measure sound. In this project, you can use the app to record the fizzing sound that the Alka-Seltzer tablet makes while it dissolves in water and then use the data to determine the reaction time and maximum sound intensity for each reaction.



Open the sensor app on your phone and select the sound sensor (audio amplitude in phyphox). Remember, that when you are using the phyphox app you will have to calibrate the audio amplitude sensor (sound sensor) before you do any measurements. Do this calibration before you start your investigation, so you get correct sound intensity readings. To calibrate your sound sensor in phyphox, follow the instructions in the sound sensor calibration video. You will have to re-calibrate the audio amplitude sensor (re-set the decibel offset) every time you start a new recording! Once you have calibrated the sensor, make sure you know where the microphone is located on your phone and do a quick test to see if your sound measurement is working. For example, you could record yourself clapping or singing to check if the sensor behaves as expected.



Once you have confirmed that the sensor works and you are familiar with the app, you can start with the experiment. You should do this experiment in a quiet environment. The background reading of your sound meter when there is no noise in the room should be in the range between 2040 decibels (dB).



Measure the temperature of the water (in Celsius [C]) in the first glass that you prepared, and record it in the data table in your lab notebook. Remove the thermometer from the glass before continuing with the next step.



Put your phone in the waterproof plastic bag and make sure it is sealed well. You don’t want it to get wet!



Place the second, same-sized glass, next to the glass filled with water. Lay your phone on top of the second glass so that the microphone (or sound sensor) is located right at the center above the glass filled with water, as shown in Figure 3.Figure 3. Place your phone on top of the glass filled with water so that the microphone (or sound sensor) is located right at the center above the solution.M. Temming





Take one whole Alka-Seltzer tablet out of its package and hold it above the glass filled with water. In the phyphox app, start a new recording for your first experiment by pressing the play button.



Once the recording starts, drop the tablet into the water. Note: You have to be very quiet during the experiment. Any sound that you make will be recorded and could affect your data. Try to be as quiet as possible while you are recording your data!



You will immediately see and hear bubbles of CO2 streaming out from the tablet.



The tablet will gradually disintegrate. Observe the graph recorded by the app, and how the sound sensor is responding to the fizzling while all of the solid white material from the tablet disappears.



When the solid material has completely disappeared, and you see on the graph that the sound intensity has reached background levels again or does not change anymore, wait 20 more seconds until all the bubbles have stopped forming, and stop recording your data. Make sure to save your data and label it appropriately such as “hot water,” “cold water” or “ice water.” Figure 4. This example data from the phyphox app demonstrates how to measure the reaction time of the Alka-Seltzer tablet dissolving. The x-axes of the graphs are time in seconds [s] and the y-axes shows sound intensity in decibels [dB].Made with phyphox by M. Temming





Your data should look something like the graph in Figure 4. Your graph should show an increased sound intensity for as long as the Alka-Seltzer reaction took place. The sound level of the reaction might be louder in the beginning and decrease as the tablet gets smaller. In the graph, every bubble that pops in the solution is represented by a spike.



Measure the time between the beginning of your reaction (when you dropped the tablet and the sound intensity started to increase) and the end of the reaction (when the sound intensity reached background levels again or does not change significantly anymore). In phyphox, you can use the pick data function to select the respective data points and view their time and decibel values. For example, the reaction in Figure 4 started a little after 3 seconds and ended at about 66 seconds.



Calculate the time difference between these two points. The result is the reaction time for your first trial. Record the reaction time (in seconds [s]) in the data table in your lab notebook.



Tip: Be careful when opening the packets and handling the Alka-Seltzer tablets. The tablets are thin and brittle, so they break easily. If some of the tablets are whole, and some are broken into many pieces, the separate trials will not be a fair test. You should only use whole tablets.





Option 2: Using the stopwatch

After filling the glass to the level of the masking tape, measure the temperature of the water (in Celsius [C]), and record it in the data table in your lab notebook.



Remove the thermometer from the glass before continuing with the next step.



Have your helper get ready with the stop watch, while you get ready with an Alka-Seltzer tablet. Have your helper count onetwothree. On three, the helper starts the stop watch and you drop the tablet into the water.



You will immediately see bubbles of CO2 streaming out from the tablet.



The tablet will gradually disintegrate. Watch for all of the solid white material from the tablet to disappear.



When the solid material has completely disappeared, and the bubbles have stopped forming, say “Stop!” to have your helper stop the stopwatch.



Record the reaction time (in seconds [s]) in the data table in your lab notebook.



Tip: Be careful when opening the packets and handling the Alka-Seltzer tablets. The tablets are thin and brittle, so they break easily. If some of the tablets are whole, and some are broken into many pieces, the separate trials will not be a fair test. You should only use whole tablets.





Repeat step 6 or 7 two more times with the same temperature of water. If you use the sensor app, make sure your sound sensor is still calibrated and recalibrate it again (re-set the decibel offset) if necessary before each recording.

Repeating an experiment helps ensure that your results are accurate and reproducible.





Repeat steps 5 and 6 or 5 and 7 for each of the other temperatures.

When you are done, you should have done a total of three trials for each of the three temperatures.





Calculate the average reaction time for each of the three water temperatures. Record your results in the data table in your lab notebook.



Make a graph of the average reaction time, in seconds (on the Y-axis), vs. water temperature, in degrees Celsius (on the X-axis).



How does reaction time change with temperature? Can you explain why this is?

Hint: If you are having trouble explaining your results, try re-reading the Introduction in the Background.





If you chose to use a sensor app to record your data, look at the graphs for each water temperature again. Write down the maximum sound intensity that you observed during the Alka-Seltzer reaction (not including the initial or end peaks) for each trial. You can get the number in the phyphox app by using the pick data tool to select the timepoint at which the sound intensity is highest. In the example shown in Figure 4, this would be around 35 seconds with a sound intensity of about 50 decibels. Calculate the average for each of the three water temperatures and record your results in the data table in your lab notebook.



Make a graph of the average maximum sound intensity, in decibels (on the Y-axis), vs. water temperature, in degree Celsius (on the X-axis).



Which reaction was the loudest? Did you expect these results?






Variations




More advanced students should also calculate the standard deviation of the reaction times for each temperature.

Use the standard deviation to add error bars to your graph.



For example, say that the average reaction time for one temperature was 45 seconds, and the standard deviation was 5.2 seconds (these are made-up numbers). You would graph the symbol for the data point at 45 seconds, and then draw short vertical bars above and below the symbol. Each vertical bar would have a length equivalent to 5.2 seconds.



Error bars give your audience a measure of the variance in your data.





Adult supervision required. Is reaction rate predictable over a larger temperature range? Water remains liquid above 0 C and below 100 C. Repeat the experiment at one or more additional high temperatures to find out. Use Pyrex glass for containing water heated on the stove or in the microwave, and use appropriate care (e.g., wear hot mitts and safety goggles) when handling hot water. A standard candy thermometer should be able to measure the temperatures in this higher range.



You could turn the bicarbonate reaction into a home-made lava lamp. To do this, you will want to use a tall jar or empty clear plastic 1-liter or 2-liter bottle, fill it with 2 to 5 centimeters (cm) of water, add 5 drops of food coloring, and then fill it at least three-quarters full with vegetable oil. You could repeat the science project using your homemade lava lamp at a cold and a hot temperature. To do this, you will need to figure out a way to make the prepared bottle hot or cold. (For example, to make it hot you could let it sit in a large bowl of hot water, and to make it cold you could store it in a refrigerator or freezer.) You will also want to use one-quarter of an Alka-Seltzer tablet at a time (instead of a whole tablet). How does the bicarbonate reaction look and function in the home-made lava lamp?




This activity is brought to you in partnership with Science Buddies. Find the original activity on the Science Buddies website.

Every big planet begins with a pebble.



Okay, not just one. It starts with lots of pebbles a flat sea of them stretching perhaps hundreds of times wider than the distance from Earth to the sun. Their sizes vary greatly. Some may be mere dust particles. Others may be small to fairly substantial rocks.



Explainer: What is a planet?



These pebbles tumble violently within the gassy disk encircling a young star. Lurking within that disk are the ingredients not only for planets, but also for asteroids, comets and living things. What they become depends not only on those ingredients, but also on their location and the temperature of the gas. 





Like fussy chefs in a kitchen, astronomers today debate over how much of which ingredients must have been present in that early solar system. And when. And how they might have interacted and combined. And what would happen if you changed their temperature.



We all know how the planet-making process ends. It produces rocky worlds like Earth, Mars and Venus. It also leads to gas giants like Saturn and ice giants like Uranus. Outside the solar system, the planetary zoo includes stranger worlds. Scientists have spotted a world that they first thought was made of diamond but now believe has oceans flowing with lava. Theyve observed a hot gas giant where drops of iron probably fall like rain and a small hot planet enshrouded in steam.



An artists interpretation of a binary star system, with a surrounding ring (in brown) that might give rise to a rocky, Mars-sized planet. JPL-Caltech/NASA



But how disks of gas and rocks become planet factories is still under debate. The beginnings where dust grains barely micrometers (a few ten-thousandths of an inch) across stick together to form rocky solids isnt too controversial. And thanks to powerful telescopes, researchers have ideas for how planets move once theyre fully-formed.



But in-between is a doozy. For centuries, scientists have been testing and fighting over ideas about how to connect the beginning to the end. Most of the seemingly best ideas have run into problems.



Over the last 10 years or so, however, a process called pebble accretion (Ah-KREE-shun) has gained popularity. Accretion refers to somethings gradual growth. This occurs as new bits of material join something or glom onto it. In this case, its a swirling disk of gas and pebbles that clump together to form a family of planets.



According to the theory, tiny rocks in the disk slow and heat up as they fly through the gas near a larger rock. Its a phenomenon similar to how water in a pond slows a sinking rock. These flying pebbles eventually spiral down to land on the surface of larger rocks nearby. Pebble by pebble, a giant planet is born. And compared to the age of the universe, its a fast process, only taking a few million years.



Pebble accretion really did revolutionize the way that people thought about planet formation, says Katherine Kretke. Shes an astrophysicist at the Southwest Research Institute in Boulder, Colo.



This theory would solve many of the riddles that challenged previous ideas. For example, says Seth Jacobson, It is really the only mechanism that comes close to explaining how Uranus and Neptune formed. Jacobson is an astrophysicist at Michigan State University in East Lansing.



Explainer: Stars and their families



Planet accretion also has gotten a boost from recent studies of distant stars. Observations by the largest radio telescope network in the world, perched on a lonely desert mountain in Chile, match up with some of this theorys unusual predictions.



Anders Johansen, an astronomer at Lund Observatory, in Sweden, knows a lot about pebble accretion. He has been one of the leading researchers arguing in its favor. Puzzling out how it might work consumes his days.



He compares studying the origins of planets to working through a detective story. The solar system provides clues in the planets we know, he says. Exoplanets beyond the solar system provide more clues. Scientists have to connect those clues to piece together the whole story.



It is just so much fun to work on this, he says.



The planet-making process has produced an incredible variety of worlds, such as these seven exoplanets that orbit the star TRAPPIST-1. JPL-Caltech/NASA



In the beginning



Ancient Greek philosophers believed that planets formed from the chaos that filled the universe. In the 17th century, French scientist and philosopher Ren Descartes suggested that every star sat at the center of a swirling vortex. Planets, made of darker stuff, rested in concentric bands that circled the star.



In the 18th century, a Swedish mystic named Emanuel Swedenborg proposed a different idea. He described planet formation in a way thats closer to modern ideas. The whole thing begins, he said, when the crusty shell around a star explodes. It crumbles. The debris settles into a giant ring encircling that star at its center. Material in that ring eventually clumps into what will become planets. The idea that the planets formed from a swirling cloud of star stuff is called the nebular hypothesis. 





That remains the backbone of ideas today. It also has led to the creation of a long list of new words. Dust doesnt refer to the stuff in your house that mix of dead skin cells, bits of cobwebs, dirt and more. Its the tiny particles too small to see with the eye. When scientists say pebble, they mean small rocks from about the size of a dime up to the size of a sled. They also talk about planetesimals (Plaa-neh-TES-ih muls). These are space rocks that might be as big as a city. Then there are protoplanets, a planet thats almost done forming. 



As scientists have hashed out the details, theyve also run into challenges. One idea popular in the 20th century, for example, proposed that planets formed from the collisions between ever-bigger rocks.



This is an artists depiction of a pebble-ridden disk surrounding the star Fomalhaut, 22 light-years from Earth. Data suggest this disk has begun separating from its sun as it dust (pebbles) have fallen onto inner planets. Larger giant plants imagined near the edge of the disk. David A. Hardy/astroart.org



That explanation, too, starts with a disk of gas and dust, notes Alessandro Morbidelli. Then the dust sticks together to form planetesimals the size of asteroids and comets. Morbidelli is a planetary scientist at the Cote dAzur Observatory in Nice, France. Just forget about the dust, he says. Then, you produce protoplanets by colliding those planetesimals with each other.



This process may sound reasonable. However, Morbidelli also believes thats almost impossible. For one thing, planets that form far from the sun grow slowly. Worlds like Jupiter and Saturn would need tens of millions of years to get so big through smash-ups. But the dust and gas disk from which they were to form only stuck around a few million years. It seems difficult by this process to grow the cores of these planets within the lifetime of the disk, he argues.



Another problem: That model requires planetesimals to collide by crossing orbits. You have all these collisions, all this debris, says Jacobson. The current planets dont look anything like that. We have very nice orbits, almost circular. They dont look like they came from a violent, messy process.



Finally, collisions between big objects dont always produce bigger objects. Its easy to check this one: Just try smashing one stone into another.



If you take two fist-sized rocks, theres no velocity at which you can bring them together and they will stick, says Jacobson. So collisions alone, he argues, cant explain how planetesimals form.



As seen in this artists illustration of the solar system (not to scale), the planets in our solar system travel roughly circular paths around the sun. But scientists know that no orbit is perfectly circular, and some veer closer and farther from the sun during their journey. MARK GARLICK/SCIENCE PHOTO LIBRARY



Paying attention to pebbles



In 2010, two astrophysicists at the Max Planck Institute for Astronomy in Heidelberg, Germany, found a workaround. The answer, they suggested, was in the disks gas. As it moves through a fluid, a solid object slows and heats up. This is due to a force called drag. Because of drag, you need more effort to walk through water than to walk through air. The drag from gas in a disk would likely slow down the pebbles.



This idea became known as pebble accretion with a study published two years later by Johansen and Michiel Lambrechts, another astronomer at Lund Observatory. They used computer models to test their ideas. In parts of the disk having the right temperatures, those pebbles can slow enough, they found, to spiral down to the surface of a planetesimal. From there theyd stay put.



It is a really efficient process, says Kretke. If you have a ton of these pebbles around at the right size, she says, then boom! You can form a planet.



Two big objects spinning through space have only a small chance of colliding. But for one big object streaming through an ocean of pebbles and dust, a collision is likely. With pebble accretion, a planet can grow as big as Neptune or Uranus during the short lifespan of the gas disk. It doesnt need giant outer-space smashups of asteroids and comets to form. And once a planet like Jupiter has a big core, its gravity can attract the lighter elements to jacket it in a thick atmosphere of hydrogen and helium.





The project Disk Detective is recruiting citizen scientists to examine NASA data on their computers and phones. Theyll be hunting dusty debris disks that may mark the birthplaces of new planets.



Pebble accretion does a good job of explaining how big planets form, says Morbidelli. It also suggests that the gas and dust in a disk determine what type of planet forms near a star or if a planet forms at all.



Or maybe it doesnt have to be a smooth disk. With pebble accretion, planets may form from misshapen rings of dust and gas that swirl around a star. In 2018, scientists studied some gas and dust orbiting stars. They used the largest radio telescope network in the world, called ALMA. (The name stands for Atacama Large Millimeter Array.) This group of giant, silvery dishes peer into space from atop a desert mountain in Chiles Atacama Desert.



What they found was shocking. Some stars have rings of dust and gas not disks. Others have large disks, or small disks. And not all rings were smooth. Some had regions where the dust and gas got stuck and clumped. Other regions seemed sparse.



We saw such diversity at the disk level, says Morbidelli.



The challenge now, he says, is to use pebble accretion to connect those ring structures to planets that may emerge.



Problems in pebbleland



Most astronomers agree that pebble accretion is a good explanation for how big planets form. Nobody questions that, says Morbidelli. But the complete explanation of how planets form is likely much more complex. Getting pebble accretion to produce planets, even in models, requires other parameters to be just right, he cautions.



For instance, pebble accretion requires a bigger rock onto which the smaller pebbles land. So we still need collisions of planetesimals to create moon-sized objects before pebble accretion takes over, he suspects. Disks must also exist filled with plenty of matter to supply all those pebbles. ALMAs observations suggest such giant disks can exist. But scientists are still collecting evidence to prove that.



Johansen and others also caution that pebble accretion likely falls short of explaining the whole story. A study published this past February showed how planetesimal collisions could have produced Jupiter, no pebble accretion needed. Gennaro DAngelo at Los Alamos National Laboratory in New Mexico and his colleagues authored the work. Their new paper doesnt rule out pebble accretion; it just shows that it may not be the only explanation for planets. Scientists still need to explore other possibilities.



Pebble accretion may not explain the formation of all planets. One recent study, for instance, showed that the planet Jupiter could have formed from collisions of planetisimals no pebble accretion required.Image data: NASA/JPL-Caltech/SwRI/MSSS; Image processing: Tanya Oleksuik (CC BY-NC-SA 2.0)



And they are. In a paper published in 2018, scientists combined planets and planetesimals in a kind of hybrid scenario.



Pebble accretion helps explain conditions under which big planets can form, DAngelo says. But that process depends on getting the timing and temperature just right. Without that, the pebbles might drift too quickly through the disk, he says, and the growing planet might not have time to accrete them.



Plus, theres a Goldilocks issue with pebble accretion. The planet-growing time has to last long enough to allow a stream of pebbles to land onto the core. But observations of other systems show that disks dont last forever. They often last only a few million years. And that puts a deadline on planet formation. So a planet cant grow too fast or too slow or it wont form at all.



Can pebbles lead to Earths?



Another lingering question about pebble accretion is whether it can form small, rocky worlds such as Earth and Mars.



Johansen thinks it can. In a February paper in Science Advances, he and his colleagues describe a model that shows how a stream of pebbles might do this. Pebbles collect on planetesimals at about the same distance from the sun as Mars is today. After the planets form, they migrate or drift over time into their current positions.





Computer simulations allow researchers to visualize how planetesimals formed, giving rise to planets, billions of years ago. Later, these visualizations suggest the neighborhood temporarily got very violent as the giant outer planets changed their orbits, wreaking tumult everywhere.



Morbidelli has his doubts. Personally, I think that somehow the giant planets grew by pebble accretion. But the terrestrial [rocky] plants, he believes, were mostly immune. Jupiter is the solar systems oldest planet. And as it grew, it blocked the flow of pebbles toward the inner solar system. That would have left no more pebbles to build the rocky planets. The solar systems inner planets, including Earth, could instead have formed through big collisions, he suspects.



Finding a way for planets to form is only the first step, says Kretke. The next question is, do we actually have a situation where pebble accretion dominates the process? In our solar system, or some other planetary system?



Scientists need better evidence before anyone declares pebble accretion to be the main planet-forming process in the cosmos. But given the wild diversity of planets both close to home and far away, he suspects scientists will find a range of explanations.



The physics is not different from here to there, he says, But the planets and the processes will depend on the conditions where they form.



Understanding those processes, says Johanson, promises two major rewards. First, scientists could understand each step in how to make a world, from dust to planet. Second, such studies could help point out where to look for life beyond the solar system.



If we want to understand habitable exoplanets, he says, we have to understand our own habitable planet.

With the availability of home DNA-test kits, people have been using samples of saliva and cells to search for, among other things, unknown relatives. But that approach will only help you narrow your search back maybe a few generations. Over the past 150 years, many scientists have attempted to hunt down our earliest ancestors folk who trace to the first emergence of humankind.



Their search hasnt been easy. Along the way, there have been varied clues and plenty of stumbles. But many have forged on in a quest that continues to this day.



The search for hominin fossils in Africa began in the 1920s. Since then, most paleoanthropologists have set their sights on eastern and southern Africa (major areas of exploration are shown). This has turned up interesting finds almost everywhere they have looked. Still, a lot of the continent is left to study. E. Otwell



Charles Darwin was among the earlier scientists to look for the ultimate roots of our family tree. Back in 1871, he hypothesized that humankinds earliest ancestors must have lived in Africa. His reasoning: Among all animals, the African apes gorillas and chimpanzees were most similar to humans. But at the time, there was no fossil evidence to support Darwins claim. The few human fossils known had all been found in Europe.



Over the next 50 years, more would trickle in from there and Asia. So had Darwin picked the wrong continent?





No. In 1924, miners in a South African limestone quarry made a surprising find. It was the fossilized skull of a toddler. Based on its features, Raymond Dart concluded this fossil was a fabled missing link between humans and apes. Dart was an anatomist at the University of the Witwatersrand in Johannesburg, South Africa. This fossil was the most apelike yet for a hominid that is, a member of the extended human family. Known as Hominidae, this family includes our species and all of our close, extinct relatives.



That fossil wasnt enough to confirm Africa as our homeland. But since that first discovery, anthropologists have amassed many thousands more fossils that have pointed to Africa as our place of origin. More recently, genetic studies have reinforced this story.



African apes are indeed our closest living relatives, with chimpanzees most closely related to us. In fact, scientists now include great apes in the hominid family. They use a more restrictive term hominin to refer to us and our most closely related extinct cousins.



Genetics show humans likely trace back to Africa



The study of human evolution is a field known for bitter feuds and rivalries. But one concept unifies these scientists: the idea that our roots go back to Africa. I think everybody agrees and understands that Africa was very pivotal in the evolution of our species, says Charles Musiba. Hes a paleoanthropologist. He works at the University of Colorado Denver.



Paleoanthropologists have sketched a rough timeline of our evolution. Sometime between 9 million and 6 million years ago, the first hominins emerged. Walking upright on two legs distinguished these ancestors from other apes. Hominins also had smaller canine teeth. That may signal they were less aggressive and more social.



Between about 3.5 million and 3 million years ago, some of our ancestors ventured beyond wooded areas. Africa was growing drier. Grasslands were spreading across the continent. Hominins were now crafting stone tools. Our genus, Homo, arrived by 2 million years ago, maybe earlier. These members of our family had larger brains than their ancestors. By at least 2 million years ago, members of our genus started moving into Eurasia. By about 300,000 years ago, our species Homo sapiens had arrived.





All in the family



But human evolution was not a gradual, linear process. It did not consist of a nearly unbroken chain, one hominin smoothly evolving into the next through time.



Fossil discoveries in the 1960s and 70s revealed a bushier family tree. These included many dead-end branches. By some counts, there may have been more than 20 hominin species. Experts disagree on how to classify them all. Fossil species are mental constructs, a paleoanthropologist once told Science News (our sister publication). 



Clearly, hominins were diverse. Indeed, some species overlapped in both time and place.



Even our species wasnt always alone. Just 50,000 years ago, the tiny Homo floresiensis nicknamed the hobbit lived on an island in Indonesia. And back 300,000 years ago, Homo naledi was a neighbor in South Africa.



Both of those species had relatively small brains. Finding such primitive cousins living at the same time as H. sapiens was a big surprise, says Bernard Wood. Hes a paleoanthropologist at George Washington University in Washington, D.C. Those discoveries, made within the past 20 years, remind us of how much is left to learn.



With so much ground in Africa and elsewhere to explore, its too early to write a complete history of human evolution, Wood says. Our origin story is still a work in progress.




Our family



Fossil finds suggest that many hominin species have lived over the last 7 million years (dates for each species are based on those finds), though researchers debate the validity of some of these classifications. The earliest purported hominins (purple) show some signs of upright walking, which became more routine with the rise of Australopithecus (green). Seemingly short-lived Paranthropus (yellow) was adapted for heavy chewing, and brain size began to increase in Homo species (blue).











H. Thompson




Eyes on Africa



One milestone in that history dates back to November 1924. Rocks containing a hominin fossil had just been brought to Raymond Darts home in South Africa. They came from a mine in the country, which was near the town of Taung. Imprinted on a knobby rock about as big as an orange were the folds, furrows and even blood vessels of a brain. It fit perfectly inside another rock that had a bit of jaw peeking out.








To celebrate its 100th anniversary, Science Newsis highlighting some of the biggest advances in science over the last century. To seean expanded version of this storyand more from the series, visitCentury of Science.




Dart slowly removed the jaw from its limestone casing. He chipped it free using knitting needles. Within a few weeks, he liberated not just a jaw but also a partial skull. It revealed the preserved face of a child.



On February 7, 1925, in the journal Nature, Dart introduced this Taung Child to the world. He described the fossil as an ape like no other. It showed some distinctly humanlike features. These included a relatively flat face and fairly small canine teeth. The hole through which the spinal cord exits the head was positioned directly under the skull. This suggested the child had an erect posture and walked on two legs.



Dart concluded that Taung Child belonged to an extinct race of apes intermediate between living anthropoids and man. His italicized text emphasized his judgment: The fossil was a so-called missing link between other great apes and humans. He named the new species Australopithecus africanus (Aw-straal-oh-PITH-ih-kus AF-rih-KAH-nus). Its name means southern ape of Africa.



Taung Child was the second hominin fossil found in Africa. It also was much more primitive than the first. Dart argued that this new find confirmed Darwins belief of humankinds African birthplace.



But most scientists were skeptical of Darts claims. It would take more than 20 years for him to be vindicated by new fossil finds and advances in geologic dating.



The Taung Child fossil that Raymond Dart studied in 1924 was the first find of a new species. Dart would go on to name it Australopithecus africanus, or southern ape of Africa. Here, a teacher examines a model of an adult A. africanus skull.Ivan Mattioli/iStock/Getty Images Plus



Against the establishment



Unlike Darwin, many evolutionists in the late 1800s and early 1900s had theorized that the human family tree was rooted in Asia. Some argued that Asias gibbons were our closest living relatives. Others reasoned that tectonic activity and climate change in Central Asia sparked human evolution. One naturalist even proposed that our origins traced back to a lost continent that had sunk into the Indian Ocean, forcing our ancestors to relocate to Southeast Asia.



By the 1890s, an Asian find emerged as the best contender for the earliest human ancestor. A crew led by Dutch physician-turned-anthropologist Eugne Dubois had uncovered a skullcap and thigh bone. It was found on Java, an Indonesian island. The thick skullcap had heavy brow ridges. Dubois estimated it once held a brain that was about twice as big as an apes and approaching the size of a humans. The thigh bone indicated that this Java Man later named Homo erectus walked upright.



Europe had its own tantalizing fossils. Neandertals had been known since the mid-1800s. But by the early 1900s, they were largely thought to be cousins that lived too recently to shed much light on our earliest evolution. A seemingly more relevant claim came in 1912. An amateur archaeologist said he found humanlike bones near Piltdown, England. Fossils of extinct creatures came from the same site. This suggested the bones from this humanlike hominin, called Piltdown Man, were really old. Skull bones hinted he had a human-sized brain. He also had a primitive jaw and large, apelike canine teeth.



Lets learn about early humans



Some experts questioned whether the skull and jaw even belonged together. But British scientists initially accepted the claim and not just because it implied England had a role in human origins. Piltdown Mans features fit with the British establishments view of human evolution. That idea held that the first trait to distinguish human ancestors from other apes was a big brain.



So scientists were ready to be skeptical when Dart announced that he had found a small-brained, upright-walking ape with humanlike teeth in the southern tip of Africa, says Paige Madison. Shes a historian of science at the Natural History Museum of Denmark in Copenhagen.



One big problem: Darts fossil was of a 3- or 4-year-old child. Critics pointed out that a young ape tends to resemble people in some ways. However, those similarities disappear as the ape matures. Critics also complained that Dart hadnt properly compared his fossil with those of young chimps and gorillas. Whats more, he refused to send his fossil to England where such analyses might easily be done.



In fact, this irked those peers in England. It was unpalatable to the scientists in England that the young colonial upstart had presumed to describe the skull himself, a scientist who knew Dart wrote much later. They felt he instead should have left its analysis to his elders and betters.



Lets learn about bias



Its hard not to wonder how the eras colonialist and racist attitudes shaped perceptions of human origins. Back then, many Western researchers offered up this perverse idea that current Africans were more primitive than other peoples, perhaps even less evolved. Many of these scientists also wanted to believe Europe or Asia is where the human line got its start.



Some anthropologists acknowledged humans could have evolved in Africa. But deep-seated biases may have made it easier for some researchers to reject the Taung Child and accept Piltdown Man even though fossil evidence for the Piltdown claim was also scant, says Sheela Athreya. Shes a paleoanthropologist at Texas A&M University in College Station.



Still, newspapers worldwide followed the Taung Child controversy.



Robert Broom unearthed fossils in the 1930s and 40s at South African caves. Those caves included the site of Sterkfontein (shown). These fossils helped convince skeptics that Australopithecus was a human ancestor.Natural History, 1947 (Linda Hall Library)



Amid it all, Dart convinced at least one well-known scientist: Robert Broom. The Scottish-born doctor, who lived in South Africa, was an authority on reptile evolution. He recognized that fossils of fully grown A. africanus individuals would be needed to confirm that the Taung Childs humanlike qualities were retained into adulthood.



In 1936, Broom started to find that evidence. And he found it in caves not far from Johannesburg. Often using dynamite to free the specimens, Broom amassed a vast collection of fossils. They came from both the young and the old. Limb, spine and hip bones confirmed South Africa had been home to an upright-walking ape. And skull bones verified Darts suspicions that A. africanus had humanlike teeth.



Even the biggest doubters of Dart couldn’t overlook Broom’s evidence. Take British anatomist Arthur Keith. Back in 1925, he had called Darts assertions preposterous. Some 22 years later he reported I am now convinced. His apology came in a one-paragraph letter to Nature. In it, he now said that Prof. Dart was right and that I was wrong; the Australopithecinae are in or near the line which [resulted] in the human form.



And Piltdown Man? A few years later, in 1953, researchers exposed it to be a hoax. Someone had planted a modern human skull alongside an orangutan jaw with its teeth filed down. Many experts outside of England had never been convinced by the find in the first place. So it was not a complete surprise when [Piltdown Man] was proved to be a fake, reported Science News Letter (an early version of Science News).



Before finding hominin fossils, Louis and Mary Leakey spent decades digging in Olduvai Gorge (shown). Their luck changed in 1959. Thats when Mary found a skull belonging to a hominin now called Paranthropus boisei. A few years later, the team found what they called Homo habilis, or handy man.Acc. 90-105 – Science Service, Records, 1920s-1970s, Smithsonian Institution Archives/Flickr



A series of surprises



It was ultimately a series of discoveries by the husband-wife team of Louis and Mary Leakey that firmly planted the idea of our origins in Africa. Louis had grown up in East Africa as the son of English missionaries. He long believed Africa was humans homeland. While Broom was mining fossils in South Africa during the 1930s, the Leakeys began exploring the Olduvai Gorge in a part of East Africa that is now Tanzania.



Year after year, the pair failed to find hominin fossils. They did, however, dig up stone tools. These suggested hominins once lived there.



So they kept looking.



One day in 1959, while an ill Louis stayed behind in camp, Mary discovered a skull with small canine teeth like Australopithecus. But this fossils giant molar teeth, cheekbones and bony crest along the top of its skull suggested something else. For its chompers, they nicknamed this fossil Nutcracker Man. Today the species is called Paranthropus boisei.



Until this discovery, figuring out the age of a hominin fossil was largely a guessing game. But new tools now allowed age calculations. In 1961, geologists used a technique that relies on the decay of radioactive elements. This potassium-argon dating showed the Leakeys skull came from a rock layer some 1.75 million years old. That was three times older than the Leakeys had suspected. (Later, A. africanus proved to be even older, living about 2 million to 3 million years ago.) The discovery vastly stretched the timescales on which scientists were mapping human evolution.



In the late 1970s, Donald Johanson and Tim White concluded that all the fossils from the Hadar site in Ethiopia, where Lucy had been found, and a site called Laetoli in Tanzania (all the fossils are shown, with Lucy at center) were from a single species they called Australopithecus afarensis and that the species was ancestral to all known hominins.D. Johanson/C.R. Palevol 2017



And the surprises didnt end there. In the early 1960s, the Leakey team recovered fossils of a hominin that lived at roughly the same time as Nutcracker Man, but had more humanlike teeth and a bigger brain. Based on that brain size and details of its hand, the Leakeys argued that this species had made the tools found at Olduvai Gorge. In 1964, Louis team placed it in the human genus with the name Homo habilis, or handy man.



The discoveries at Olduvai Gorge kicked off a fossil gold rush in Africa. A 1974 discovery in Ethiopia, for instance, once again expanded the timescale of human evolution. It was one of the most famous discoveries of all. A nearly 40 percent complete skeleton was found. Called Lucy, she was the most complete example of Australopithecus afarensis, a species from 3.2 million years ago.



Since then, more fossils have stretched the hominin fossil record in Africa back even further to some 6 million or 7 million years ago. Thats about when ancestors of people and chimps likely parted ways.



On the origin of our species



Still, one big question remained: Where did Homo sapiens, our species, emerge?



In the mid-1980s, anthropologists had a basic picture of our evolution: Hominins had arisen in Africa. Nearly 2 million years ago, H. erectus became the first of our ancient cousins to venture outside of Africa. In some places, H. erectus persisted for a long time. Elsewhere, new groups appeared in Europe and Asia. Somehow, at some point our species arrived and all others disappeared.



Since then, that somehow has been at the center of a lot of debate. And over just the last decade, genetic and fossil revelations have helped to sharpen an ever more complex picture of our origins.



One emerging view suggests that much of early human evolution occurred in Africa. Yet there was no one place on the continent where H. sapiens was born. Starting at least 300,000 years ago, fossils with modern H. sapiens features started to show up. But these features didnt all arise at the same place.



People across the globe today can exhibit a range of very different features. Some anthropologists believe that despite such variations, people are actually quite similar, especially on the genetic level.Jasmin Merdan/Moment/Getty Images Plus



Only through the mating of different populations across Africa did the suite of behaviors and other traits that define us today come together, says Eleanor Scerri. Shes an evolutionary archaeologist. She works at the Max Planck Institute for the Science of Human History in Jena, Germany.



Our origins lie in the interactions of these different populations, she says. Little is known about those interactions. Why? She says its because scientists have explored so little of ancient Africa.



Theres still much to explore in other parts of the world, too. One single explanation of how our species evolved may never be possible, says Athreya, at Texas A&M University. The reason: Different processes likely shaped human history in different parts of the world.



See stories from our Science Is for Everyone series



Better understanding of our roots will come from new discoveries, tech advances and, importantly, new perspectives. For the last 100 years, our origin story has been told by mostly white, mostly male scientists. Welcoming more diverse groups of scientists into these studies, Athreya says, could reveal big blind spots and biases as they add to and amend the tale.



This is, after all, everyones story.

WhenJennifer Johnsonand her team embarked on theirannual quest to survey the sturgeon population in the Detroit River in mid-April 2021, they had fully expected to find some super-sized specimens.However, theU.S. Fish and Wildlife Service biologists had never anticipated luring in thegranddaddy of all sturgeons a massive, 240-pound, 6-foot, 10-inch long fishthat they estimate is at least a century old!

It was spring break and everyone walked out of school ready for a break, but little did we know we wouldnt come back. About a week after spring break started the world stopped. Restaurants closed. School virtual. Roads empty. When school went virtual my parents left to go to work because they were essential workers. That day was the first time I was home alone, the first time I did school virtually, and the first time, I was scared to leave my house. Days, weeks, and even months passed and everything that was new turned normal. Wake up, get ready for school, stare at a computer, do homework...

Butterflies and bees do it. Frogs and even salmon do it. What is it? Its metamorphosis.



The term describes a series of dramatic physical changes that an organism undergoes as it matures. The term comes from the Greek word for change of form.



Lets learn about amphibians



Lots of young animals look different from their parents. But metamorphosis is distinct from just growing up. Some animals emerge from metamorphosis with brand-new organs, such as wings or lungs. Others switch what types of food they eat or may wind up not eating at all! These differences may benefit animals by minimizing competition for resources between adults and babies of the same species.Insects, amphibians and certain fish are among the more well-known animals that metamorphose. But theyre not the only ones. Jellyfish, mollusks and sea stars have all been observed undergoing this real-life shapeshifting. Crabs, lobsters and other crustaceans have, too.





Body remodel



Many animals that metamorphose have babies that look entirely different from their adult forms. Think of a frog. Frogs have powerful back legs and lungs. But many frog species start life underwater as tadpoles. Unlike frogs, tadpoles rely on gills and long tails to maneuver underwater.



Jellyfish, meanwhile, start out as free-swimming young called larvae. These larvae attach to hard surfaces and transform into anemone-like polyps. These polyps spend much of their early lives using their tentacles to catch passing prey. Eventually, the tentacles begin to bud into free-floating jellies. They then detach from their home surface and hit the high seas.



Like jellyfish, sea urchins also start their lives as larvae swimming in the ocean. These larvae use long arms to snag phytoplankton to eat. During metamorphosis, a sea urchin grows adult limbs and organs from a cluster of cells inside its body called a rudiment. The urchins absorb their larval arms and mouths into their bodies. Then they drop to the seafloor as newly formed adults.



These spiky purple sea urchins started out life as free-swimming larvae before they underwent metamorphosis into their current forms.Brent Durand/Getty Images


Insect transformations



Metamorphosis is especially common in insects. But some insect transformations are more dramatic than others.



Take butterflies. A crawling, leaf-munching caterpillar can transition into a flying, nectar-sipping butterfly within a few weeks. This is an example of complete metamorphosis. During this type of metamorphosis, insects go through four life stages: egg, larva, pupa and adult. At each stage, the insect will look completely different.



Explainer: Insects, arachnids and other arthropods



The process begins with an egg laid by an adult. A small, soft-bodied larva, such as a caterpillar, hatches from this egg. Larvae do not have many of the organs found in adults. And they have one goal: eat as much as they can.A caterpillar doesn’t have wings, doesn’t have any reproductive organs, says Jens Rolff. It’s just like a big bag of tissues moving on a plant and feeding. Constantly feeding. Rolff is an evolutionary biologist who studies insects. He works at Freie Universitt in Berlin, Germany.Healthy appetites help a larva pack on fat. And that will fuel the development of its organs once the larva becomes a pupa. At the pupa stage, the larva stops eating and develops a protective covering. Caterpillars develop a hard, outer layer called a chrysalis.







When the larva pupates, the job is to generate a new animal, says Rolff. Inside the pupa, proteins called enzymes begin to break down the larvas tissues. These dissolved tissues are used to rebuild muscles and organs such as the brain and gut. Special groups of cells called imaginal discs become activated and help create wings, new mouthparts and reproductive organs. Once these changes are complete, an adult insect emerges.



That adult often moves and eats in totally different ways than it did as a pupa.



About eight in every 10 insect species undergo complete metamorphosis. Beetles, flies, bees, ants and fleas are just a few examples. Together, this group makes up about 60 percent of all animals on Earth. Complete metamorphosis has been around for a while, too. Fossils suggest that insects were doing it at least 250 million years ago, Rolff says.





Check out one of the worlds largest beetles going through metamorphosis in this video from Nat Geo WILD.



Not all insects go through this full process, though. Grasshoppers, cockroaches, cicadas and dragonflies go through a three-stage version known as incomplete metamorphosis.



Here, insects emerge from eggs as nymphs, which look much like miniature adults. They are just missing developed wings and sex organs. Nymph forms of these species gradually get larger by shedding their hard outer shell, or exoskeleton, through a process called molting. Wings and reproductive organs continue to develop with each molt. All insects grow by molting. But insects that undergo complete metamorphosis only do so while plumping themselves up as larvae. Nymphs will go through multiple molts until they reach adulthood.

On July 8, 2021,Zaila Avant-garde outspelled 11 finalists to clinchthe prestigiousScripps National Spelling Bee title.The 14-year-old from Harvey, Louisiana, is the first African American and only the second Black winnerin thenationalcompetition's 93-yearhistory. The first wasJody-Anne Maxwell from Jamaica, who won in 1998 at the age of 12.Avant-gardeis also Louisiana'sfirstspelling bee champion!

Lightning may play an important role in clearing the air of pollutants.



A storm-chasing airplane has shown that lightning can forge large amounts of oxidants. These chemicals cleanse the atmosphere by reacting with pollutants such as methane. Those reactions form molecules that dissolve in water or stick to surfaces. The molecules can then rain out of the air or stick to objects on the ground.



Supercell: Its the king of thunderstorms



Researchers knew lightning could produce oxidants indirectly. The bolts generate nitric oxide. That chemical can react with other molecules in the air to make some oxidants. But no one had seen lightning directly create lots of oxidants.





A NASA jet got the first glimpse of this in 2012. The jet flew through storm clouds over Colorado, Oklahoma and Texas in both May and June. Instruments on board measured two oxidants in the clouds. One was hydroxyl radical, or OH. The other was a related oxidant. Its called the hydroperoxyl (Hy-droh-pur-OX-ul) radical, or HO2. The airplane measured the combined concentration of both in the air.



Explainer: Weather and weather prediction



Lightning and other electrified parts of the clouds sparked the creation of OH and HO2. Levels of these molecules rose to thousands of parts per trillion. That may not sound like much. But the most OH seen in the atmosphere before was only a few parts per trillion. The most HO2 ever seen in the air was about 150 parts per trillion. Researchers reported the observations online April 29 in Science.



We didnt expect to see any of this, says William Brune. Hes an atmospheric scientist. He works at Pennsylvania State University in University Park. It was just so extreme. But lab tests helped confirm that what his team saw in clouds was real. Those experiments showed electricity really could generate lots of OH and HO2.



Scientists Say: Climate



Brune and his team calculated how much of the atmospheric oxidants that lightning could produce around the world. They did this using their storm-cloud observations. The team also accounted for frequency of lightning storms. On average, some 1,800 such storms are raging around the globe at any point in time. That led to a ballpark estimate. Lightning could account for 2 to 16 percent of atmospheric OH. Observing more storms could lead to a more precise estimate.



Knowing how storms affect the atmosphere may become even more important as climate change sparks more lightning.

On Jupiter, lightning jerks and jolts a lot like it does on Earth. 



New views of storms on Jupiter hint that its lightning bolts build by lurching forward. Whats more, those staggering steps happen at a similar pace to lightning bolts on our own planet. 



Arcs of lightning on both worlds seem to move like a winded hiker going up a mountain, says Ivana Kolmaov. A hiker might pause after each step to catch their breath. Likewise, lightning on Earth and Jupiter both seem to build by one step, another step, then another, Kolmaov says. Shes an atmospheric physicist at the Czech Academy of Sciences in Prague. Her team shared the new findings May 23 inNature Communications.  





The discovery about Jupiters lightning doesnt just offer new insights into this gas giant. It could also help aid in the search for alien life. After all, experiments hint that lightning on Earth could have forged some of the chemical ingredients for life. If lightning works a similar way on other worlds, it might produce lifes building blocks on distant planets, too. 



Lightning, step by step 



Here on Earth, winds within thunderclouds whip up lightning. The winds cause many ice crystals and water droplets to rub together. As a result, those tiny bits of ice and water become electrically charged. Bits with opposite charges move to opposite sides of the clouds, building up charge on either end.  



Lets learn about lightning



When that charge buildup gets big enough, electrons are released the lightning takes its first step. From there, the surging electrons repeatedly rip electrons off molecules in new segments of air and rush into those segments. So the bolt of lightning leaps forward at tens of thousands of meters per second, on average. 



Scientists thought Jupiters lightningmight also form by ice crystals and water droplets colliding. But no one knew whether the alien bolts grew step by step, as they do on Earth, or if they took some other form. 



Views from Juno 



Kolmaovs group looked at data from NASAs Juno spacecraft. Specifically, they looked at pulses of radio waves given off by Jupiters lightning. The data included hundreds of thousands of radio wave pulses from lightning over five years. 



Radio waves from each lightning bolt seemed to happen about once per millisecond. On Earth, lightning bolts that stretch from one part of a cloud to another pulse at about the same rate.This hints that Jupiters lightning builds in steps that are hundreds to thousands of meters long, too. 







Step-by-step lightning is not the only possible explanation for what Juno saw, says Richard Sonnenfeld. Hes an atmospheric physicist who wasnt involved in the study. He works at the New Mexico Institute of Mining and Technology in Socorro.   



The radio pulses could have come from electrons running back and forth along bolts of lightning, Sonnenfeld says. On Earth, such currents cause some bolts to appear to flicker. Still, he says, stop-and-go lightning formation is a perfectly reasonable explanation for the data. 

Depictions of extinct human ancestors and cousins often are more art than science.



Take Australopithecus africanus. This member of the human family tree, or hominid, lived millions of years ago. Scientists made two sculptures showing what this hominid might have looked like. The busts were based on the skull of a child that lived 2.8 million years ago. One bust was made using a sculptors intuition. It appears more apelike. The second, made with a scientists help, appears more humanlike.



These two images of what an Australopithecus africanus child may have looked like depend on an artists personal decisions. Those decisions make the child appear more apelike (left) or humanlike (right).G. Vinas, R.M. Campbell, M. Henneberg and R. Diogo



Now, the team has come up with guidelines to make more accurate portraits of species known only from fossilized bone. The reconstructions of the past, most of them did not have a scientific basis, says Rui Diogo. Our goal is to change the methods and to change the biases, he says. That should give a more accurate view of human evolution. His team reported its new guidelines February 26 in Frontiers in Ecology and Evolution.



Getting the depictions right matters, says Diogo. He is a biological anthropologist at Howard University in Washington, D.C. Museum visitors often see artists renditions of Neandertals or extinct hominids as reality. But those visitors may not realize the work is biased. And that can skew peoples views. It can even bolster prejudices about present-day people.



The Smithsonian National Museum of Natural History in Washington, D.C. is a perfect example. An exhibit of extinct hominids shows skin getting lighter as species began walking upright. But there is zero evidence to say the skin was whiter, Diogo says. That depiction might reinforce the incorrect and racist idea that people with lighter skin are more evolved.



Accurate depictions of extinct members of the human family tree begin with scans of fossilized bones. This digital scan was made using a cast of the original Taung child’s skull.G. Vinas, R.M. Campbell, M. Henneberg and R. Diogo



Scientists and artists often work together to depict our ancestors. But their choices may be driven more by whim than science, Diogos team says. By studying muscles in the great apes and other nonhuman primates, the team has created reference databases. Those databases are part of the Visible Ape Project. Scientists could use them to reconstruct faces from fossils. Even then, the choice of an ape or a human as a starting point can lead to different outcomes.



Artists depictions also can give faulty ideas about the intelligence and behavior of extinct people. Neandertals are often shown with matted, dirty hair, says Ryan Campbell. He studies anatomy at the University of Adelaide in Australia. There is a bias toward portraying our ancestors as if they were stupid and didnt have hygiene, he says.



But animals of all kinds groom themselves. There is no reason to think that Neandertals were different. In fact, showing our ancestors without hair might be more accurate, Campbell says. Hair is rarely preserved in fossils. And DNA data from bones may hint at hair color. But the data dont reveal grooming habits.

For centuries, the study of human origins relied on fossils. Scientists wanted to know from which species Homo sapiens descended and to which we were most closely related. For answers, they could do little more than compare the size, shape and orientation of preserved bones and teeth perhaps along with tools and other artifacts. That all changed by the 1980s.








To celebrate its 100th anniversary, Science Newsis highlighting some of the biggest advances in science over the last century. To seean expanded version of this storyand more from the series, visitCentury of Science.



Read more






Scientists started looking at the DNA of people alive today as a way to understand our past. Then in the 1990s, genetics pulled off a feat straight out of science fiction: It decoded the DNA preserved in the fossils left by our ancient ancestors.



It was a pivotal change in the study of human evolution, notes John Hawks. Hes a paleoanthropologist. He works at the University of WisconsinMadison. That ancient DNA, he says, began revealing things no one had even thought to look for.



DNA started offering clues about our evolution in 1987.



Thats when researchers at the University of California, Berkeley analyzed DNA from people living around the world. They focused on whats known as mitochondrial DNA. Children inherit this mtDNA from their mothers. It undergoes no genetic reshuffling. So mtDNA preserves a mothers ancestry going back millennia.



African populations showed the greatest genetic diversity in mtDNA. And when the Berkeley team built a family tree using their genetic data, it contained two main branches. One held only African lines. The other contained lineages from all over the world, including Africa.





Searching for a Garden of Eden



This suggested the mother lineage for them all had come from Africa.



Based on the estimated rate at which mtDNA changes over time, the team calculated that this African Eve must have lived some 200,000 years ago. It reported its conclusions in Nature.



But not everyone interpreted the genetic evidence the same way. Some argued that perhaps African populations in the distant past had been much larger than other ancient groups. Maybe thats why the African mtDNA appeared dominant. Also, they noted, mtDNA isnt a complete record of inheritance. It doesnt, for instance, show dads genes.



Year by year, ever more data accumulated. With each new dating technique used and each discovery unveiled, the idea as Africa as the source of human evolution only strengthened.



Our species is Homo sapiens. In 2003, fossil evidence would suggest the earliest fossil sites for this species were in Ethiopia. They dated to between 195,000 and 160,000 years ago. More recently, scientists linked roughly 300,000-year-old fossils in Morocco to our species.



Another genetic window into our collective past opened in 1997. Thats when researchers recovered mtDNA from a Neandertal fossil. Leading the team was Svante Pbo. Hes a geneticist now at the Max Planck Institute for Evolutionary Anthropology. Its in Leipzig, Germany. This mtDNA was so different from any modern humans that it suggested Neandertals must be a separate species.



A recently discovered piece of finger bone (brown) is shown with colorized, digital images of the original bone fragment from Siberias Denisova Cave. The bones DNA revealed that a new hominin had interbred with humans, much as Neandertals had. It was the first hominin discovered through genetics. (mm = millimeters)E.A. Bennett et al/Science Advances 2019



A decade later, Pbo was part of a team that assembled the Neandertals genetic blueprint, or genome. They compared it with DNA from modern humans. And this led to a startling conclusion: About 1 to 4 percent of DNA in non-Africans today traces back to Neandertals.



Those data seemed to revise the model for human origins. Yes, the new idea went, we originated in Africa. But once our ancestors expanded into new places, some mated with other hominins (closely related species that are now extinct). Hints of such hybrids were reported in the late 1990s. Thats when some researchers claimed an ancient skeleton from Portugal had a mix of Neandertal and human features.



Pbos group also analyzed DNA from a finger bone found at Siberias Denisova Cave. Both Neandertals and modern humans had once lived there. But the DNA from fossils in this cave didnt match either group. The genetics revealed a new hominin. These folk, now known as Denisovans, remain mysterious. They are known from only a few bits of bone and teeth. But they, too, interbred with humans. For instance, Denisovan DNA accounts for about 2 to 4 percent of the DNA in people native to some Southwest Pacific island nations.



Fossil and genetic evidence seem to suggest that throughout time and across continents, groups of human ancestors mated with other groups. The groups came from different lands and likely looked different from one another. Some researchers think that the sharing of genes through this mixing enabled ancient folks across Africa, Asia and Europe to stay a unified species. And this species gradually evolved into what we think of as modern humans. Yes, these researchers say, there may have been some substantial regional variations in skin color, eye colors and more. But the underlying species everywhere were now the same: human.

I heard a car pulling into the driveway. Soon enough, Adam, my Grandson, burst into my room, with a broad grin. Wow, you are right on time for my interview! I remarked cheerfully. Of course! I want top marks for this interview for my school science project! Adam replied ecstatically, So, lets start. Grandpa, please tell me the story of Covid-19 and how it changed your life! Well, as you know, I am a professor of biology. However, did you know that the pandemic fifty years ago was the reason I decided on that path? As I continued, I felt myself being pulled into the memories of 2020...

Modern-day rhinos,which weigh anywhere from 1,800 to5,100 pounds, are no lightweights. However, they pale in comparison totheir prehistoric cousinthat roamed China about 26million years ago.The massive mammal weighed 46,000 pounds almost as much as four largeAfricanelephants. Standing ata heightof23ft (7m), it was alsotaller than a giraffe.

A seriesof deadly tornadoesswept across a large swath of the Midwestern and SoutheasternUS overnight onDecember 10, 2021.TheNational Weather Service (NSW)estimates that the severe storms spawned about50 twisters across eight states Arkansas, Indiana,Kentucky, Missouri, Mississippi, Tennessee, Ohio, and Illinois.

On February 12, 2021, over a billion people in China and millions worldwidewill celebratethe first day of the Chinese New Year. Also known as the Lunar New Year, orSpring Festival,the exactdate of the 15-daycommemoration, which marks the end of winter, is determined by the lunar calendar. Itfalls somewhere between late January to mid-February each year.

Four of your senses are located just on your head. Taste is in your mouth. Smell is in your nose. Sight in your eyes and hearing in your ears. But touch? Touch is all over your body. Your fingertips and face can sense touch, and so can the bottoms of your feet and the backs of your knees. Its completely essential. Without it we wouldnt know if we stubbed our toes or burned our skin. 



See all the entries from our Lets Learn About series



Your skin (and your organs, bones and muscle) is full of receptor cells for different aspects of touch. These cells might respond to pressure or heat. They could respond to something that causes pain. Some of these receptor cells can also respond to cold and different chemicals. Each of the receptor cells connects to a sensory neuron. These are cells that send information back to the spinal cord and brain. There, your brain processes the touch your receptors felt, and determines whether you just tried to pet a cat or a cactus. Some areas of your body are more sensitive to touch than others, which is why you pet a cat with your hand and not with your back.



Its pretty easy to fool our eyes, ears or noses with sights, sounds and scents. But touch? Thats tougher. Scientists are working on haptic devices technologies that can mimic our sense of touch. Some use stretchy fabrics to make our skin feel something thats not there. Others are using sound waves that we cant hear to make illusions real to the touch.





Virtual reality is mostly sight and sound right now. But with the power of haptics, it could be touch, too.



Want to know more? Weve got some stories to get you started:





Touching allows octopuses to pre-taste their food: Special sensory cells in suckers in the animals arms sense chemicals. Those cells allow them to taste the difference between food and poison. (1/4/2021) Readability: 7.1



This artificial skin feels ghosts things you wish were there: Engineers have developed a wearable device that simulates the sense of touch. It may benefit robotic surgery and deep-sea exploration. (11/20/2020) Readability: 6.4



Testing the power of touch: We pet dogs with our fingers, not our arms or backs. Our fingers are more sensitive to touch. But how do we know? Here’s how you can test that. (2/5/2020) Readability: 6.3





Explore more



Scientists Say: Neuron



Explainer: What is skin?



Explainer: What is a neuron?



Shaking hands could transfer your DNA leaving it on things you never touched



Feeling objects that arent there



A do-it-yourself map of touch



Activities



Word Find



Some areas of our bodies are more sensitive to touch than others. In fact, you can measure your skin sensitivity and draw a map of it with a free program. The resulting misshapen body is called cortical homunculus. Its a representation of how our brain perceives touch all over our bodies.

Whale hunting has plundered the seas of giant whales for much of the last century. With the help of modern technology, people have killed up to 99 percent of certain species. Some scientists thought this would cause krill the tiny crustaceans that many whales gulp down to explode in number. But that didnt happen. New research suggests whale poop, or a lack of it, may explain this.



Explainer: What is a whale?



Krill numbers in Antarctic waters with lots of whale hunting have dropped by more than 80 percent. With fewer of these crustaceans, many other krill predators have gone hungry, such as seabirds and fish.



A new study looked at the eating habits of baleen whales (those that use long keratin plates of baleen to help snag prey). These include blue and humpback whales. Apparently, baleen whales eat about three times as much food as we thought. Lots more food means lots more poop. That poop is rich in iron. So with fewer whales, ecosystems get less iron and other crucial nutrients that they need to thrive. That hurts other species, including krill. 





The team shared its findings in the November 4 Nature. Restoring whale populations, the researchers say, could help these ecosystems recover.



Its hard to know what role whales play in ecosystems without knowing how much theyre eating, says Joe Roman. This marine ecologist wasnt involved in the new study. He works at the University of Vermont in Burlington. How much whales eat had not been well known, he says. This study will allow us to better understand how the widespread depletion of whales has impacted ocean ecosystems.





Whale of a problem



Gauging whale diets is not easy. Some of these animals are around the size of Boeing 737 jets. They gulp down hordes of centimeter-long invertebrates that live far below the surface of the ocean. In the past, scientists have relied on assessing what these behemoths eat by dissecting the stomachs of dead whales. Or researchers estimated how much energy whales should need based on their size.



These studies were educated guesses, says Matthew Savoca. But, he adds, none were conducted on live whales in the wild. Savoca is a marine biologist at Hopkins Marine Station. Part of Stanford University, its in Pacific Grove, Calif.



Lets learn about whales and dolphins



New technology allowed Savoca and his colleagues to get a more precise estimate of what whales eat. He notes that this was a chance to answer a really basic biological question about some of the most charismatic animals on Earth.



His team needed to know three things. First, how often do whales feed? Second, how big is each of their gulps of prey? And third, how much food is in each of those gulps? To gather these data, the team suction-cupped sensors to the backs of 321 whales. They came from seven different species. The sensors tracked when the whales lunged for prey. Drones also snapped photos of 105 whales to help the researchers estimate gulp size. Finally, sonar mapping revealed the density of krill in the whales feeding areas.



Researchers approach two humpback whales near the West Antarctic Peninsula in an effort to attach specialized sensors via suction cup to track the animals feeding behavior.Duke University Marine Robotics and Remote Sensing under NOAA permit 14809-03 and ACA permits 2015-011 and 2020-016



Combining these data provided a more detailed look at feeding than ever before, says Sarah Fortune. Savoca and his colleagues measured all the things you need to measure to get an accurate estimate of consumption. Fortune is a marine ecologist who did not take part in the new study. She works at Fisheries and Oceans Canada in Vancouver, British Columbia.



On average, baleen whales eat about three times as much food as earlier estimates had suggested. For example, a blue whale can gulp down 16 metric tons of krill about 10 million to 20 million calories in a day. Thats like one of these supersized creatures wolfing down 30,000 Big Macs, Savoca says. 



Whales dont eat that much every day. At times when the animals are migrating vast distances, they may go months without taking a bite. But the sheer volume of food that they eat and then poop out suggests that whales play a far bigger role in shaping ocean ecosystems than we thought, Savoca says. That makes the loss of whales that much more harmful.



Why whales are a big deal



Whales are nutrient cyclers. They feed on iron-rich krill in the deep sea. Later, they return some of that iron to the surface in the form of poop. This helps keep iron and other crucial nutrients in the food web. Hunting whales might have broken this iron cycle. Fewer whales bring less iron to the oceans surface. With less iron there, phytoplankton blooms shrink. Krill and many other creatures that feast on phytoplankton may now suffer. Such changes will make the ecosystem suffer, Savoca says. 



As big animals poop out



The industrial hunting of whales killed millions of the huge animals in the 20th century. Researchers now estimate that before then, baleen whales in the Southern Ocean alone consumed 430 million metric tons of krill each year. Today, less than half that amount of krill lives in those waters. Smaller whale populations are likely the reason for this, Savoca says. When you wholesale remove them, the system becomes, on average, less [healthy]. 



Some whale populations are rebounding. If whales and krill returned to their early 1900s numbers, the productivity of the Southern Ocean could be boosted by 11 percent, the researchers calculate. That increased productivity would translate into more carbon-rich life, from krill to blue whales. Together, those creatures would store 215 million metric tons of carbon each year. The carbon stored in those creatures wouldnt be able to escape into the atmosphere and contribute to global warming. It would be like taking more than 170 million cars off the road each year.



Whales are not the solution to climate change, Savoca says. But rebuilding whale populations would help a sliver, and we need lots of slivers put together to solve the problem.

On the heels of the spectacularMay 26, 2021, total lunar eclipsecomesanothercelestial spectacle. On June 10, 2021, some lucky stargazers willwitness this year's first of two solar eclipses. Sinceit isan annular, not a total, eclipse, the Sun's edges will be visible around the Moon,transforming the star into a stunning "ring of fire."

Our seemingly calm Sun can havea nasty temperthat comes in the form of powerful explosions. The star'sunpredictable outburstscandisruptsatellites in orbit andbe dangerous forastronauts.Though the flares are well-documented, researchers have never been able to pinpoint thecause of the erratic behavior. Now, the Sun'sincrediblemulti-staged "tantrum"may help scientists get closer to solving thelong-standing mystery.