[airborne]

When you have too many people in a tribe, it’s more difficult to feed everyone.

Makes sense for groups to separate to look for better hunting grounds.

[null and void]

Makes sense for groups to separate to look for better hunting grounds.

Or just to get away from all the snoring!

[SunkenCiv]

I dunno about that, those statues of really fat chicks in sites like Catal Huyuk leads me to believe that there were Peg Bundy types in prehistoric times.

[Farmerbob]

[When you have too many people in a tribe...]

Or when the ruling class become too greedy, you decide to gather your women, move beyond the frontier, and take your chances with the 4 legged predators.