Another R1b paper

The peopling of Europe and the cautionary tale of Y chromosome lineage R-M269 (full text freely accessible):
Recently, the debate on the origins of the major European Y chromosome haplogroup R1b1b2-M269 has reignited, and opinion has moved away from Palaeolithic origins to the notion of a younger Neolithic spread of these chromosomes from the Near East. Here, we address this debate by investigating frequency patterns and diversity in the largest collection of R1b1b2-M269 chromosomes yet assembled. Our analysis reveals no geographical trends in diversity, in contradiction to expectation under the Neolithic hypothesis, and suggests an alternative explanation for the apparent cline in diversity recently described. We further investigate the young, STR-based time to the most recent common ancestor estimates proposed so far for R-M269-related lineages and find evidence for an appreciable effect of microsatellite choice on age estimates. As a consequence, the existing data and tools are insufficient to make credible estimates for the age of this haplogroup, and conclusions about the timing of its origin and dispersal should be viewed with a large degree of caution.
I find it hard to get too excited about this paper. As discussed previously, amateurs looking at more finely-resolved subclades using larger numbers of STRs do find trends in diversity that seem to point to an E. European origin for W. European R1b. I expect we'll have to wait a couple years, for overwhelming evidence to accumulate in the form of ancient DNA results and SNP-based dating, before seeing the correct route and timing of the entry of R1b into Europe widely agreed upon by academics. BBC article:
The extent to which modern Europeans are descended from these early farmers versus the indigenous hunter-gatherers who settled the continent thousands of years previously is a matter of heated debate. [. . .]

More than 100 million European men carry a type called R-M269, so identifying when this genetic group spread out is vital to understanding the peopling of Europe. [. . .]

A more recent origin for R-M269 than the Neolithic is also possible. But researchers point out that after the advent of agriculture, populations in Europe exploded, meaning that it would have been more difficult for incoming migrants to displace local people.

From the paper:
If the R-M269 lineage is more recent in origin than the Neolithic expansion, then its current distribution would have to be the result of major population movements occurring since that origin. For this haplogroup to be so ubiquitous, the population carrying R-S127 would have displaced most of the populations present in western Europe after the Neolithic agricultural transition.
Although the debate is commonly framed as Paleolithic vs. Neolithic, many lines of evidence suggest the correct answer is the third option: major post-Neolithic population movement.

5 comments:

hailtoyou said...

A near-total racial-replacement of Paleolithic Europeans is impossible for one simple reason:

Anthropological continuity between Paleolithic Cro-Magnon Man and modern Europeans exists and is documented. (Including on racehist, if memory serves).

Further, R1b is most common in areas of Europe with the highest frequency of observable (and documented) Cro-Magnid racial-types, as identified by anthropologists. Places with fewer Cro-Magnids and more Dinarids, Alpinids, Mediterrnanids...they have less R1b. Advociates of replacement cannot easily explain this away: Were Paleolithic Cro-Magnon Europeans replaced by a group of people that looked exactly the same as them?

n/a said...

Hail,

I may reply later in a separate post, but briefly:

- The evidence for the recent eastern origin of R1b stands on its own. Under no reasonable scenario can the Paleolithic W. Euro theory be salvaged.

- Replacement of Y chromosomes doesn't imply replacement of autosomal DNA (though in this particular case complementary evidence for a substantial recent autosomal contribution from the east exists in the form of genes for light pigmentation and lactose tolerance). Some mtDNA lineages (and on the paternal side, some lineages of Y haplogroup I) probably reflect Mesolithic W. Euro contributions to NW Europeans.

- The Indo-European invaders were at least partly of Paleolithic European ancestry themselves.

- The picture emerging from DNA is very consistent with that inferred from skeletal remains by physical anthropologists like Coon.

Anonymous said...

"though in this particular case complementary evidence for a substantial recent autosomal contribution from the east exists in the form of genes for light pigmentation and lactose tolerance."

Can I see the evidence for that.

As for LT I thought the European form evolved around Hungary. Thus it doesnt provide evidence for a migration from the steps to W. Europe.

n/a said...

Anonymous,

We don't know exactly where the LCT mutation originated. We do know it's relatively young and distributed from Ireland to India. In The 10,000 Year Explosion, Greg Cochran and Henry Harpending argue for a link to IE: "the advantage driving those Indo-European expansions was biological--a high frequency of the European lactose-tolerance mutation (the 13910-T allele)." Another group has suggested a link to the Neolithic LBK culture (and thus Hungary), but this attribution was based on a computer model and has found no support from ancient DNA.

Researchers have estimated the allele for blue eyes (which I believe is distributed about as widely as LCT) originated around 8000 years ago.

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