Wednesday, February 11, 2015

Reich Paper Offers Wealth Of European Ancient DNA

A pre-print of a new paper by Reich, et al., offers a wealth of new ancient DNA information for Europe, including Y-DNA, mtDNA and autosomal DNA from the Mesolithic era through the late Bronze Age.

Most eagerly awaited is the new Y-DNA data (internal citations omitted):
We determined that 34 of the 69 newly analyzed individuals were male and used 2,258 Y chromosome SNPs targets included in the capture to obtain high resolution Y chromosome haplogroup calls. Outside Russia, and before the Late Neolithic period, only a single R1b individual was found (early Neolithic Spain) in the combined literature (n=70). By contrast, haplogroups R1a and R1b were found in 60% of Late Neolithic/Bronze Age Europeans outside Russia (n=10), and in 100% of the samples from European Russia from all periods (7,500-2,700 BCE; n=9). R1a and R1b are the most common haplogroups in many European populations today and our results suggest that they spread into Europe from the East after 3,000 BCE. Two hunter-gatherers from Russia included in our study belonged to R1a (Karelia) and R1b (Samara), the earliest documented ancient samples of either haplogroup discovered to date. These two hunter-gatherers did not belong to the derived lineages M417 within R1a and M269 within R1b that are predominant in Europeans today, but all 7 Yamnaya males did belong to the M269 subclade of haplogroup R1b.
The big surprise is that all of the Yamnaya Y-DNA was R1b-M269, which is now typical of Western Europe and the Northern European coast, in addition to the R1b of Samara which was a Mesolithic (i.e. hunter-gatherer) culture that preceded the Yamnaya culture in essentially the same geographic location. R1b-M269 is predominant in the Basque people, despite the widely held belief that their ancestors were not linguistically Indo-European, and the only Bell Beaker individual for whom Y-DNA data has been obtained (from Germany) is also R1b-M269.

Conventional wisdom had expected that the Yamnaya people were R1a-M417 bearing men who gave rise to the Corded Ware culture that produced the Y-DNA R1a predominance seen in Central and Eastern Europe today.  The genetic evidence tends to favor a NE European rather than SE European proximate source of R1a in Central Europe.

Karelia where the Mesolithic R1a sample was found is in modern day Russia just to the east of Finland.

The autosomal DNA data also provides new insights but is not so easily summarized.  Some notable observations:

* Eight of the nine Bell Beaker individuals for whom ancient autosomal DNA is available (all from one of two sites in Germany) are women.  Bell Beaker individuals have a considerably smaller Ancestral North European component than contemporaneous Corded Ware culture individuals.

* There are eight ancient autosomal DNA samples from the Unetice culture from sites in Germany. They have very similar automsomal DNA profiles to the Bell Beaker individuals.  But despite this similarity, all three of the men in the Unetice sample have Y-DNA I2.

* Y-DNA I2 is also found in five Swedish Mesolithic men, one early Neolithic man from Spain, two Middle Neolithic men from Spain, one Middle Neolithic man from Germany, one late Neolithic man from Germany, and two early Bronze Age men from Germany.

* The branching trees created using autosomal DNA similarities do not match the ones that would be inferred from Y-DNA data.

* The population discontinuity between the first farmers of Europe (LBK, etc.) and the linguistically Indo-European R1a/R1b populations that followed disfavors the Anatolian hypothesis of Indo-European language origins.


bellbeakerblogger said...

Despite the disparity of uni-parental markers of these sixteen individuals, the relatively similar autosomes of Unetice to Beaker may suggest genetic continuity between the two. A general material culture evolution, I believe has been a majority view.

Most of the Western Bronze age cultures could be described as "McBeaker"

terryt said...

"the relatively similar autosomes of Unetice to Beaker may suggest genetic continuity between the two".

I find it quite easy to imagine a haplogroup (especially Y-DNA) expansion independent of a more general genetic expansion. In other words it is quite possible for the Y-DNA line to change with minimal a-DNA change. On the other hand I would be surprised if any haplogroup expansion did not at least start out with an associated a-DNA expansion, but Y-DNA can expand beyond the a-DNA expansion margin. The same seems to be true of languages of course.

andrew said...

"I find it quite easy to imagine a haplogroup (especially Y-DNA) expansion independent of a more general genetic expansion."

I've spent a fair amount of time since the paper came out trying to imagine just that. It is easy to imagine ways in which it is "possible" for that to happen. Coming up with a "plausible" total narrative that explains that is considerably more challenging, and while I have several half baked outlines in my head of how that could happen, I am not comfortable that I really have any narrative that I'm really comfortable that I've worked out and could stand behind yet that does so (although obviously, there is some narrative that really did happen and does explain the facts, so it isn't an impossible task).

terryt said...

"while I have several half baked outlines in my head of how that could happen"

I didn't mean it would be easy to work out patterns using the idea!!

terryt said...

I've just noticed Maju has woken from his long slumber and posted on the subject. You might find he offers some useful insights.