As many of you know, I've been following with bemused interest the Grand Invasion of Europe hypothesis that Wolfgang Haak is trying to construct over on this Eurogenes Blog.
The latest is that Wolfgang, AKA "Davidski", has declared that half of European ancestry arrived from the Ponto-Caspian Steppe.
Way down in the comment thread, on February 1, 2015 at 1:22 PM, we finally get some hard references for his assertion: He comments regarding this paper that:
"The authors argue that the Kurgan people most likely came from Europe, and their mtDNA became increasingly Asian as they mixed with Asians."
Wolfgang and his cohorts have tried to use autosomal DNA to "prove" that "Kurgan people" migrated from the Steppe into Europe during the Bronze age on one massive sweeping invasion.
This is what the Keyser et al paper to which "Davidski" refers says:
"Our autosomal, Y-chromosomal and mitochondrial DNA analyses reveal that whereas few specimens seem to be related matrilineally or patrilineally, nearly all subjects belong to haplogroup R1a1-M17 which is thought to mark the eastward migration of the early Indo-Europeans."
Wolfgang doesn't mention it, but the archaeological sites discussed in the Keyser et al paper are in the Altai, about a thousand miles east of the Caspian Sea.
That being said, the idea of an eastward migration from Eastern Europe into areas such as Moldova and the Ukraine is supported by another paper, the Varzari et al paper:
"Our results show that a significant majority of the Moldavian paternal gene pool belongs to eastern/central European and Balkan/eastern Mediterranean Y lineages. Phylogenetic and AMOVA analyses based on Y-STR loci also revealed that Moldavians are close to both eastern/central European and Balkan-Carpathian populations. The data correlate well with historical accounts and geographical location of the region and thus allow to hypothesize that extant Moldavian paternal genetic lineages arose from extensive recent admixture between genetically autochthonous populations of the Balkan-Carpathian zone and neighboring Slavic groups."
Autosomally speaking, groups from Western Russia and the Ukraine can only be discerned from other European populations by very low level admixture components, which appear to be associated with Northeast Asian populations at less than about the 5% level. You can see these low level components in populations such as Mordovinians and Ukrainians. See, for instance, the Rasmussen et al paper discussed in this post. These low level components are the only thing that differentiate, for instance, a Bulgarian from a Mordovinian. Otherwise, autosomally, groups from the Balkans are very similar to groups from eastern/central Europe.
Moreover, groups from eastern/central Europe are very similar, autosomally, to populations from Western Europe such as Orcadians and the French.
Most Western Europeans also have, at very low level (< 1%) some Northeast Asian ancestry.
From the Varzari et al paper, it is also clear that the Balkans and eastern/central Europe show many of the same ydna hg and mtdna hg lineages.
So here's the problem: Wolfgang makes the definitive statement that "Half of our ancestry comes from the Pontic-Caspian steppe". Further, he asserts that this occurred in one massive wave during either the Bronze or Copper age (at this point, I'm not sure which. It keeps changing.)
Given the apparent homogeneity between the Balkans and eastern/central Europe, and only very low level trace differences between Steppe groups such as Mordovinians, and many populations in Europe, how are Wolfgang Haak and his colleagues are able to discern, with razor sharp accuracy in time and place, the difference between Ponto-Caspian Steppe populations, Balkan populations and eastern/central European populations?
A few ancient DNA samples, with nothing from the Balkans, I might add, cannot be sufficient to support the grand assertion of a 50% displacement of the population of Europe in the last five thousand years.
From available data, there is no basis on which to make a sweeping statement like Half of European ancestry arrived from the Ponto-Caspian Steppe.