Linear Population Model is a no comments blog for the understandable reason that it takes too much time to moderate blog comments, so rather than posting comments there, I'll engage with some of the concerns raised by Marnie here at this blog.
Marine opens up the issue with this premise:
You may know that the Eurogenes blog (along with some very prominent researchers) has been heavily and stubbornly promoting the theory of a very sudden invasion of Europe during the Copper Age from either the Ponto-Caspian Steppe or the Central Asian Steppe.After setting up the position expressed by Davidiski at the Eurogenes blog fairly accurately and discussing some other relevant data, Marnie gets to the bottom line issue he is raising:
So what's with thinking that R1 lineages were simply confined to the Central Eurasian steppe for 20,000 years (and not to Europe until the Copper age)?The most important data supporting the Eurogenes position come from several data sets of Central and Eastern European ancient DNA (e.g. Germany and Hungary).
There definitely is a shift of modern Europeans between the Mesolithic and today. I agree with that.
But I don't agree that the shift happened due only to replacement from the Ponto-Caspian or Central Eurasian Steppe and only during the Copper Age.
It's just as likely that the genetic shift of Europeans is due to Western Europeans fusing with populations of Finland, Scandinavia, the Baltic, Balkans (including Greece), Central Europe, the Ukraine, Russia, Anatolia, and the Levant, starting in the Mesolithic and continuing to the present day. It would have been a complex process, with waves of people possibly moving both in and out of the Steppe and in and out of Europe, since the R/Q/P split.
Ancient DNA samples from this region cluster into three groups.
1. Samples that precede the Neolithic revolution (the Neolithic revolution begins when the first farmers appears in this part of Europe; this initial Neolithic archaeological culture is often called the "Linear Pottery Culture" or LBK for short) including Upper Paleolithic and Mesolithic samples and also samples from European hunter-gatherer populations in the region (as determined based upon the archaeological context of the ancient DNA) who were contemporaneous with the first farmers of the region.
These samples are predominantly mtDNA U4 and U5, and the handful of autosomal samples that are available are very distinct from those of subsequent farming populations which derive only part of their ancestry from European hunter-gather like sources. There are very few pre-Neolithic European samples of ancient Y-DNA available, but all that are available are Y-DNA I2.
While there is a decent case that Southern Europe saw some enrichment in its mtDNA diversity in the Mesolithic era, I don't think that the case is nearly as strong for what became LBK cultural zone in the early Neolithic era.
2. Samples from farmers of the early Neolithic era (i.e. from the beginning of the LBK culture until roughly the start of the Corded Ware culture in the Copper Age).
These samples have a minor component of mtDNA haplogroups similar to those found in the Mesolithic era and among hunter-gatherers contemporaneous with them, but with many new mtDNA haplogroups that aren't found in older samples. The dominant Y-DNA haplogroup is G2.
3. Samples from the Copper Age (roughly coincident with the arrival of the Corded Ware culture) to the present in this region.
From the Copper Age onward, the ancient DNA strongly resembles the modern population genetics of the region. It is highly enriched in mtDNA haplogroup H relative to the early Neolithic where it was uncommon, or the Mesolithic era where mtDNA H was absent.
The frequency of Y-DNA G2 is dramatically reduced and Y-DNA I2 is also quite uncommon, while, Y-DNA R1a (and really a very specific subset of Y-DNA R1a which a most recent common ancestor estimated to date from the Copper Age by admittedly imperfect mutation rate dating methods) is predominant. In some regions, there is a blend of Y-DNA R1b (and again actually a specific European subset of R1b with similar estimate time depth), the predominant Y-DNA type of much of Western Europe and areas near the Southern Baltic Coast of Europe, near the biogeographic boundary between R1a predominance and R1b predominance that roughly corresponds to the historical ranges of the Bell Beaker people (or cultures in continuity with them) in the West, and with the Corded Ware people (or cultures in continuity with them) in the East, during the Copper and Bronze Ages in Continental Europe.
The limited ancient autosomal DNA fits this clustering with a shift from the LBK DNA profile towards the modern profile represented by a new ancestry component that is detected, appearing in ancient DNA starting around the Copper Age.
There is also Bronze Age ancient DNA and physical anthropology data showing genetic continuity and continuity in physical appearance and bone structure of people from the Corded Ware region of Europe all of the way to the Tarim Basin at the fringe of the East Asian highlands of greater China, where mummies reveal individuals who were Eastern European in their genes, coloration and bone structure, who we know spoke a long lost Indo-European language called Tocharian until around the time of an expansion of linguistically Altaic peoples across the Eurasian steppe all of the way to Europe itself.
Evidence from the time depth of language families in Europe also tends to support this analysis.
In the interests of not letting this post get too stale, I am posting it now. But, I hope to enrich it with additional links and references over the next few days.
UPDATE: A new ancient DNA find reported at Eurogenes appears to further support this hypothesis.