Y-chromosome haplogroup R1b has turned up in two late Neolithic skeletons from a Bell Beaker burial site at Kromsdorf, eastern Germany, with one of the lineages further defined as R1b1b2 (M269+). This is a breakthrough, because for years, geneticists and genetic genealogists have been wondering which archeological culture to credit for the massive expansion of this haplogroup in Europe.
For a long time it was thought R1b was a Cro-Magnon marker native to Western Europe, but that theory fell by the way side when its ancestor R1 was found to be only 18,500 years old (see here). There was then some talk about R1b being a proto-Indo-European lineage, which expanded with Yamnaya pastoralists from the Eastern European steppe. This was a notion mostly entertained by hobby genetic genealogists from Western Europe and the US, but it never really made any sense, due to the paucity of R1b in modern-day Ukraine and Southern Russia.
However, many others, including myself, always had a suspicion that the Bell Beaker folk played an important role in the spread of R1b across Western Europe. Indeed, I mentioned them last week in my blog post about ancient DNA from the Swedish Neolithic, saying they probably had an impact on the genetics of Scandinavians during the Copper Age (see here).
A couple of mtDNA sequences from the samples in this study - those belonging to haplogroups K1 and I1 - are apparently showing haplotype hits in Portugal, as reported here. That's important, because the Bell Beaker "phenomenon" is thought to have originated in present-day Portugal, and then expanded into other areas of Western Europe via maritime routes, before moving onto Central Europe. However, both K1 and I1 are native to the Near East, and most likely arrived in Iberia after the Ice Age. Indeed, the same can probably be said about R1b. What this suggests is that the elements that crystallized into the Bell Beaker Culture in Iberia during the late Neolithic came from the Near East during the Neolithic.
Below is a map showing the approximate extent of Bell Beaker usage (source: Wikipedia).
By the way, it's useful to note that back in 2008 R1a was found in ancient skeletons at a burial site in Eulau, not far from the Kromsdorf Bell Beaker site, and from roughly the same period (see here). However, these skeletons belonged to individuals from the materially and anthropologically very different Corded Ware culture. Thus, it appears as if the two main haplogroups of present-day Europeans, R1a and R1b, can be associated with two major European archeological cultures of the late Neolithic: Corded Ware in the east, and Bell Beaker in the west, respectively. Amazing stuff.
The transition from hunting and gathering to agriculture in Europe is associated with demographic changes that may have shifted the human gene pool of the region as a result of an influx of Neolithic farmers from the Near East. However, the genetic composition of populations after the earliest Neolithic, when a diverse mosaic of societies that had been fully engaged in agriculture for some time appeared in central Europe, is poorly known. At this period during the Late Neolithic (ca. 2,800–2,000 BC), regionally distinctive burial patterns associated with two different cultural groups emerge, Bell Beaker and Corded Ware, and may reflect differences in how these societies were organized. Ancient DNA analyses of human remains from the Late Neolithic Bell Beaker site of Kromsdorf, Germany showed distinct mitochondrial haplotypes for six individuals, which were classified under the haplogroups I1, K1, T1, U2, U5, and W5, and two males were identified as belonging to the Y haplogroup R1b. In contrast to other Late Neolithic societies in Europe emphasizing maintenance of biological relatedness in mortuary contexts, the diversity of maternal haplotypes evident at Kromsdorf suggests that burial practices of Bell Beaker communities operated outside of social norms based on shared maternal lineages. Furthermore, our data, along with those from previous studies, indicate that modern U5-lineages may have received little, if any, contribution from the Mesolithic or Neolithic mitochondrial gene pool.
Update 29/04/2013: There's a new website up called Haplogroup R1b. It's raising funds to study ancient DNA remains in the hope of finally solving the mystery of where European R1b came from (see here). I don't know who's behind the effort, and whether it's legitimate, but their articles are informative and well balanced. Here are some quotes from a piece about the Kromsdorf samples titled R1b and the Bell Beaker Phenomenon.
Busby et al. stated that an east to west migration could not be inferred based on STR variance of R1b1a2’s largest European subclade, R-L11 (aka S127) which makes sense in a rapid spread scenario.
Unfortunately the distribution of L11(xP312,U106) is too fragmented and samples too few to draw any conclusion about its origin. The lack of a variance cline is probably the result of a rapid expansion and is attested by similar STR modal values for the three major subclades of R-P312 (aka S116), which are U152, DF27 and L21. In fact, it is at this level that a slight difference in variance (Table 1) and GD (Table 2) can be observed. [Walsh, B. Computing Genetic Distances, (24 Nov. 2003), http://nitro.biosci.arizona.edu/ftDNA/Distance.html, (visited 27 Jun 2012)] The increased variance and decreased genetic distance from P312 makes a case for U152 being the oldest subclade of P312. As such, it is also the likeliest to have occurred near the P312 origin point (Figure 2).
DF27 = Maritime Beaker expansion out of Iberia
U152 & L21 = Reflux expansion from the Alps which would give rise to Italo-Celtic
If we take radio carbon data into account which tells us the earliest Bell Beakers occurred in Iberia, an out-of-Iberia DF27 expansion becomes even more intriguing. Finally, if we take the definition of the North South cluster as one with a Northern and Southern coastal distribution, it aligns with the expansion of Maritime Bell Beakers along the Atlantic and Mediterranean coasts. Maritime Bell Beaker cluster seems more appropriate at this time than North-South cluster. There has finally been an Iberian L165 sample found, which would mean the 10x Isles sample bias may be in play.
If we look at the variance of DF27′s siblings, we see that they are younger than DF27 and may have been involved in the later Bell Beaker reflux expansions. The ordering of variance (1. DF27 2. U152 3. L21) is also a good match for radio carbon dating that shows Bell Beaker age as oldest in Iberia/S. France/N. Italy and then progressively younger as one goes north and east.
Lee et al., Emerging genetic patterns of the European Neolithic: Perspectives from a late Neolithic Bell Beaker burial site in Germany, American Journal of Physical Anthropology, Article first published online: 3 MAY 2012, DOI: 10.1002/ajpa.22074
Karafet et al., New binary polymorphisms reshape and increase resolution of the human Y chromosomal haplogroup tree, Genome Research, Published in Advance April 2, 2008, doi: 10.1101/gr.7172008