Large-scale recent expansion of European patrilineages shown by population resequencing:

The proportion of Europeans descending from Neolithic farmers ~10 thousand years ago (KYA) or Palaeolithic hunter-gatherers has been much debated. The male-specific region of the Y chromosome (MSY) has been widely applied to this question, but unbiased estimates of diversity and time depth have been lacking. Here we show that European patrilineages underwent a recent continent-wide expansion. Resequencing of 3.7 Mb of MSY DNA in 334 males, comprising 17 European and Middle Eastern populations, defines a phylogeny containing 5,996 single-nucleotide polymorphisms. Dating indicates that three major lineages (I1, R1a and R1b), accounting for 64% of our sample, have very recent coalescent times, ranging between 3.5 and 7.3 KYA. A continuous swathe of 13/17 populations share similar histories featuring a demographic expansion starting ~2.1–4.2 KYA. Our results are compatible with ancient MSY DNA data, and contrast with data on mitochondrial DNA, indicating a widespread male-specific phenomenon that focuses interest on the social structure of Bronze Age Europe.

Looking at this paper, it basically confirms what we know from ancient DNA, and other large scale sequencing projects. Until recently much Y chromosomal phylogenetic analyses were done utilizing highly mutable regions, microsatellites. This had a major upside, in that variation was copious. But, it wasn’t as precise as more slow mutating regions of the genome would have been. But without next generation sequencing the Y chromosome is just hard to work with due to its paucity of SNP variants. So that’s why we’re seeing some gains here.

The relatively homogeneity in Northern Europe in particular is attributed to a few lineages which have gone through “star-like” expansions. That aligns rather well with the idea that the arrival of populations from the steppe was demographically an earthquake.