David Reich

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.

And in fact, the Yamnaya people actually lose out in that interaction.

And in fact, the Corded Ware males absorb and take Yamnaya females

And they actually also take farmer females, because you actually see these sites in early Corded Ware sites in Czechia where both things are happening.

Females from farmers and females from Yamnai are being absorbed into the Corded Ware community, and then they expand further.

So what you actually have is a two-step process where you have a male Yamnai expansion, and then that ancestry from the steppe is carried further through females being absorbed into the Corded Ware, and then another male-driven expansion under the Corded Ware.

and so on.

And that brings both female and male Yamnaya lineages west, but not always with the Yamnaya ancestry being associated with the kind of intuition that you would think it's domination.