Population Density

What led to the birth of human civilization? How did a naked ape manage to invent complex cultural forms such as language and art? One possibility is that something happened inside the mind, that a cortical switch was flipped and homo sapiens was suddenly able to paint on cave walls. But that doesn't seem to be the case, as UCL anthropologist Ruth Mace explains in a recent Science article:

Traits such as the creation of abstract art, improvements in stone and other tools, long-distance "trading