Question

What if everyone lived in 1 country, or one city

Answer 1

If so, overpopulation* would be a bigger issue because that one area would be densely packed with people.

*=overpopulation: when an area's population becomes too large

Answer 2

Hm, at first there would be the problem of overpopulation, and lack of needs, and crime, and then there would probably be a bunch of murder and probably a few random people who try to save half of the people by killing the other half, in a different way of doubling resources, and then there would be some smart people to just go "Wait... if it's too crowded here, couldn't we just go over here-"

Answer 3

Well, that would be a problem. There might not be enough water for everyone, and overpopulation (When in an area, the population is more than the capacity.) would be more of a problem. And there would be crime everywhere.