This is yet another teaser for the upcoming Corded Ware/Yamnaya paper from the Reich lab. Sadly, it doesn't mention Y-chromosome haplogroups, so perhaps the authors are going to tackle this issue later. However, check out what they say about the German and Spanish farmers being of the same stock, and the resurgence of hunter-gatherer ancestry in Western Europe after the early Neolithic. Fascinating stuff.
Ancient DNA points to the Eurasian steppe as a proximate source for Indo-European migrations into Europe
David Reich and Nick Patterson
Abstract: We generated genome-wide data from 65 Europeans who lived between 8,000-3,000 years ago by enriching ancient DNA libraries for a target set of about 390,000 single nucleotide polymorphisms. This strategy decreases the sequencing required to obtain genome-wide data from ancient DNA samples by around 1000-fold, allowing us to study an order of magnitude more individuals than previous studies and to obtain new insights about the past. We show that in western Europe, the farmers of both Germany and Spain >7,000 years ago were descended from a common ancestral stock. These farmers did not replace the earlier hunter-gatherers, but continued to mix with them, leading to a resurgence of hunter-gatherer ancestry in both Germany and Spain ~1,000-2,000 years later. In eastern Europe, the hunter-gatherers of Russia >7,000 years ago were distinct from those of the west, having an increased affinity to a ~24,000 year old individual from Siberia, but this affinity was reduced by ~5,000 years ago in the Yamnaya steppe pastoralists because of admixture with a population of Near Eastern ancestry. Western and Eastern Europe collided ~4,500 years ago with the appearance of the Corded Ware people in Central Europe, who derived at least two thirds of their ancestry from an eastern population closely related to the Yamnaya. The evidence for mass migration into Europe thousands of years after the arrival of agriculture, in combination with linguistic and archaeological data, makes a compelling case for the steppe as a proximate source for the spread of Indo-European languages into Europe.
Source: INA Kolloquium Ws 2014/15
Update 11/02/2015: Massive migration from the steppe is a source for Indo-European languages in Europe (Haak et al. 2015 preprint) .