David Reich on social inequality and Yamna expansion with few Y-DNA subclades

Interesting article from David Reich that I had missed, at Nautilus, Social Inequality Leaves a Genetic Mark.

It explores one of the main issues we are observing with ancient DNA, the greater reduction in Y-DNA lineages relative to mtDNA lineages, and its most likely explanation (which I discussed recently).

Excerpts interesting for the Indo-European question (emphasis mine):

Gimbutas’s reconstruction has been criticized as fantastical by her critics, and any attempt to paint a vivid picture of what a human culture was like before the period of written texts needs to be viewed with caution. Nevertheless, ancient DNA data has provided evidence that the Yamnaya were indeed a society in which power was concentrated among a small number of elite males. The Y chromosomes that the Yamnaya carried were nearly all of a few types, which shows that a limited number of males must have been extraordinarily successful in spreading their genes. In contrast, in their mitochondrial DNA, the Yamnaya had more diverse sequences.⁹ The descendants of the Yamnaya or their close relatives spread their Y chromosomes into Europe and India, and the demographic impact of this expansion was profound, as the Y-chromosome types they carried were absent in Europe and India before the Bronze Age but are predominant in both places today.¹³

This Yamnaya expansion also cannot have been entirely friendly, as is clear from the fact that the proportion of Y chromosomes of steppe origin in both western Europe¹⁴ and in India¹⁵ today is much larger than the proportion of the rest of the genome. This preponderance of male ancestry coming from the steppe implies that male descendants of the Yamnaya with political or social power were more successful at competing for local mates than men from the local groups. The most striking example I know is from Iberia in far southwestern Europe, where Yamnaya-derived ancestry arrived suddenly at the onset of the Bronze Age between 4,500 and 4,000 years ago. Daniel Bradley’s laboratory and my laboratory independently produced ancient DNA from individuals of this period.¹⁴ We find that in the first Iberians with Yamnaya-derived ancestry, the proportion of Yamnaya ancestry across the whole genome is almost never more than around 15 percent. However, around 90 percent of males who carry Yamnaya ancestry have a Y-chromosome type of steppe origin that was absent in Iberia prior to that time. It is clear that there were extraordinary hierarchies and imbalances in power at work in the Yamnaya expansions.

David Reich clearly doesn’t give a damn about how other people might react to his commentaries. That’s nice.

In any case, if anyone was still in denial, R1b-M269 expanded with Yamna (through the Bell Beaker expansion) into Iberia, hence yes, 90% of modern Basque male lineages have an origin in the steppe, like the R1b-DF27 sample recently found, and their common ancestor spoke Late Proto-Indo-European.

Findings like these, which should be taken as normal developments of research, are apparently still a trauma for many – like R1a-fans from India realizing most of their paternal ancestors came from the steppe, or its fans from Northern Europe understanding that their paternal ancestors probably spoke Uralic or a related language; or N1c-fans seeing how their paternal ancestors probably didn’t speak Uralic. It seems life isn’t fair to stupid simplistic ethnolinguistic ideas…

Let’s see which Y-DNA haplogroups we find in West Yamna, to verify the latest migration model of Late PIE speakers of the Reich Lab (featured image).

Check out also the BBC News coverage of David Reich and Nick Patterson, the two most influential researchers of the moment in Human Ancestry: How ancient DNA is transforming our view of the past.

Related:

• Consequences of O&M 2018 (III): The Balto-Slavic conundrum in Linguistics, Archaeology, and Genetics
• Early Indo-Iranian formed mainly by R1b-Z2103 and R1a-Z93, Corded Ware out of Late PIE-speaking migrations
• Y-DNA haplogroup R1b-Z2103 in Proto-Indo-Iranians?
• Consequences of O&M 2018 (I): The latest West Yamna “outlier”
• Olalde et al. and Mathieson et al. (Nature 2018): R1b-L23 dominates Bell Beaker and Yamna, R1a-M417 resurges in East-Central Europe during the Bronze Age
• Reactionary views on new Yamna and Bell Beaker data, and the newest IECWT model
• The Indo-European demic diffusion model, and the “R1b – Indo-European” association
• The concept of “Outlier” in Human Ancestry (III): Late Neolithic samples from the Baltic region and origins of the Corded Ware culture
• New Ukraine Eneolithic sample from late Sredni Stog, near homeland of the Corded Ware culture