[I've said this stuff a number of times, but there is no obvious URL to point to, so here's a summary]
Seventy thousand years ago humans were very different. Superficially it wasn't that different from more modern hunter gatherers. People lived in groups (quite in-bred promoting cooperation). They made tools. They talked about the weather and the food options and who was doing what with whom. But look closer and there is little to call art or music, and nothing changes over thousands of years.
Then culture started and around 30,000 years ago it swept the world. Most obviously there is art, and there is invention and change in tools and clothing and housing. What I mean by "culture" is things that groups adopt to distinguish themselves from other groups. Groups love to distinguish themselves:
- "We are the group that dresses like this"
- "We are the group that speaks and understands this language and these idioms"
- "We are the group that makes this sort of pottery"
- "We are the group that plays and enjoys this sort of music"
And these things require skills that take years. Foreigners can't just walk in and blend in.
Culture takes up a lot of brain power and a lot of time and effort. Why was it so successful in displacing the simple lifestyles that preceded it?
Intergroup conflict is a characteristic of our species, and indeed of related species such as chimpanzees. For a graphic discussion of this, see Jared Diamond's book The World Until Yesterday. Before Culture, groups were limited to ones where everyone knew everyone else. Culture allowed us to create groups that were defined by common culture. These could be much larger.
So that's it. Culture allowed us to create big groups that beat up the small groups of pre-cultural humans. At first the pre-cultural females would be absorbed by the victors, diluting the culture genes and slowing things down. But by 30000 years ago the dilution process became insignificant and the takeover of cultural genes went very rapidly to completion.
We love cultures generally and our own particularly. So this is not quite the story we would want to hear. But we need to understand how we got here if we are going to make good decisions about where to go.