David Reich

I just think we don't have important new qualitative insights about that topic right now.

The other is that the large brain was already in place prior to the separation of Neanderthals and modern humans, and maybe Denisovans as well.

So already the common ancestors of Neanderthals and modern humans probably had a brain as large as ours.

It's not obvious that there's parallel evolution in multiple parts of the world.

It may be that it's a sufficiently interconnected group that it's not a parallel evolution event, but a single process.

I think that's almost certainly true.

We don't yet know the frequency of exchange between Africa and Eurasia, but this is two million years.

It's a lot of time.

You know, Paul Salopek is like walking around the planet in like seven or...

years or something like this.

People move incredibly quickly.

And Africa and Eurasia are not really separated by barriers that mean anything very important to a species like ours over periods of even dozens or hundreds or thousands of years.

So the idea that being in Eurasia or Africa is such a profound barrier that you would not expect people to move from one region to the other in periods of tens of thousands of years or hundreds of thousands of years, that's a strange idea.

So this is outside my area of expertise of being very much like a scientist right here, but I'm very sympathetic to the idea that it's hardly genetic.

So I think that this is cultural innovation.

It's very natural to think that this is cultural innovation.

And humans sometimes develop a new technique of storing information, sharing information,

and so on, for example, writing, which allows you to record collective knowledge in a library or computational knowledge or large storage devices and so on and so forth.

Language, conceptual language, which allow you to create a cultural body of knowledge.

Well, I don't know what the language was.