David Reich

to the forested parts of Europe, which is most of Europe, and somehow the ancestry of the Yamnaya gets absorbed by the Corded Ware group, and then later the Beaker group, and that takes it further through Europe.

But the Corded Ware group is quite different from the Yamnaya culturally, and in fact a lot of archaeologists think that they're so different they can't be the same.

They have some shared features, but the Corded Ware have many different traditions.

One possibility is that the Yamnaya expand, and they encountered early Corded Ware.

The Corded Ware learned some of the adaptations of the Yamnaya, and then they actually take Yamnaya women, absorb them into Corded Ware, mostly male communities, and create a new community, and that group expands.

So one of the mysteries of the Yamnaya expansion was everybody had this cognitive bias to think this is very male-driven.

People have these Indo-European notions of sort of male-centered mythologies and so on.

So this must be an extremely male-centered migration, a very male-centered migration.

You look at the genetic data and you look at the Y chromosomes, which track male migration,

and the mitochondrial sequences, which are more sensitive to female migration.

And it looks like the step expansion from the east to west is very both sexes.

Both males and females expand.

And people have found this confusing, and there's been a lot of incredulity about this.

People expect to see that it's an even...

movement of males and females, but it's quite clear that the bias is not so strong.

And we think the most likely explanation for what's happening now is that it actually is a male biased process, but it's one that's interrupted.

So the Yamnaya expansion is very male biased.

It expands to the edge of the range.

They encounter the Corded Ware complex people.

And then what happens is the Corded Ware complex people interact with the Yamnaya people.