Razib Khan One-stop-shopping for all of my content

October 5, 2012

The rise of the farming lineages

Filed under: Genetics,R1b,R1b1b2 — Razib Khan @ 8:02 am

There’s an open access paper/preprint on Y chromosomal lineages that just came out, A calibrated human Y-chromosomal phylogeny based on resequencing. Since it is open access you can read the whole thing (it’s short). Let me quote from the discussion:

Nevertheless, the rapid expansion of R1b (and possibly I1) in Europe contrasts with the less starlike expansion of E1b1a in Africa, which has been associated with the spread of farming, ironworking and Bantu languages in Africa over the last 5,000 years (Berniell-Lee et al. 2009). Both R1b and E1b1a samples are from a mixture of indigenous donors (from Europe and Africa, respectively) and admixed American donors, so sampling strategy does not provide an obvious explanation for the difference. Instead, the different phylogenetic structure, with far more resolution of the individual E1a1a branches, may reflect expansion starting from a larger and more diverse population, and thus retaining more ancestral diversity.

R1b is the most common haplogroup in Western Europe. This group places its growth 4-13,000 years ago. That suggests to them a Neolithic expansion. I am moderately confident in this number because ancient DNA extraction has not found much R1b in Europe 5-10,0000 years before the present, even though this lineage ...

May 5, 2012

Bell Beakers and R1b

Filed under: Ancient Europe,Anthroplogy,Bell Beaker,R1b — Razib Khan @ 11:20 pm

Over at Dienekes blog he has a post up about the extraction of R1b from a male who lived in Germany 4-5,000 in the past. This is important because R1b is one of the two most common male lineages (on the Y chromosome, passed from father to son) in Europe, and, it has inexplicably been underrepresented or absent in the ancient DNA samples. The other modal lineage is R1a (it too is underrepresented).

I have a pretty good grasp of variation on the autosomal dimension. A modest familiarity with uniparental lineages, Y and mtDNA. And finally, a rather weak understanding of archaeological patterns. Since mtDNA tends to be found at very high concentrations in subfossil remains you’ll get a good yield of that in the near future (as in the paper Dienekes covers). Y chromosomal information is more difficult. The problem with autosomal information is that you need more of it to make robust genealogical inferences (due to confounding with selection, as well as recombination breaking apart haplotypes), though if you manage to hit a functional region that can be very informative.

I assume in the year 2020, and perhaps well ...

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