Joseph Henrich

Yeah.

So a typical assumption when people think about this, if you put it in the Paleolithic, they assume that it has to do with some kind of genetic changes.

Now, Reich's lab, you know, there's no obviously big changes in the DNA.

So it's a little bit of a puzzle.

Neanderthals, for example, had larger brains.

And in primates, larger brains usually goes along with more computational abilities, more ability to solve problems.

So the expanding variant out of the Middle East, out of Africa, might have actually been less able at an individual level to process information.

But if you look back over the more recent period of human history, you can see that it's a story of expansions of different populations.

So, for example, in Africa, we have the Bantu expansion about 5,000 years ago, which actually eliminates a whole bunch of hunter-gatherer populations that previously existed in Africa.

We have the remnant populations in parts of the Congo, in the Kalahari, in the Hadza, for example, in Tanzania.

If you look at the Austronesian expansion, so that's the peopling of the Pacific.

That was the expansion of one group of people at the expense of others.

And of course, the Neolithic expansion into Europe is another example.

So really, human history is a story of these different expansions.

And it could be that this expansion across Eurasia, which then led to interbreeding.

So we know it's the same species.

Humans interbred with Denisovans and Neanderthals, as well as probably other species.

There's a ghost species in there.

Yeah.

This could be just institutional changes.