Joseph Henrich

And in a world without very much cumulative culture, there's not going to be very much useful information in the minds of everybody else.

So I should use that brain tissue for individually solving problems.

And so it's hard to get this runoff where our brains get bigger for the purposes of learning from others.

So, and then the question is, how do you get past that valley?

So, the case I make in secret is that in the, say, 3 million years ago, 2 million years ago, there were several factors that came together.

The first factor is the rate of change of environments.

So, you get this increase in the fluctuation of environments.

So, you're getting more environmental changes.

And in cultural evolution, a lot of theory shows that there's a certain rate of change which is favorable to cultural evolution.

It's got to be slow enough so that the information is – of your parents and the previous generation is useful but not so slow that you might as well just encode it in the genes.

So that's one.

Second thing is we're a ground-dwelling ape, which means we have hands like chimpanzees and gorillas, and we can potentially use tools and whatnot.

But unlike them, our ancestors may have been savanna-dwelling apes, which meant we may have lived in large groups.

So in mammals, mammals live in larger groups when they have to deal with predators.

And the predator guild in Africa at that point was quite thick.

There were a lot of deadly predators.

So paleoanthropologists think that our ancestors may have lived in large savanna-dwelling apes.

And if you have a lot of individuals, if the culture is sparse, the bigger the group, the more chance that there's someone doing something useful in the larger group.

And so that means it's easier to get across the threshold.

So those are three of the main factors that might have allowed our lineage as opposed to all the other lineages around to cross this.