Finally some good research on R1b1b2!

This is a most important paper for those interested in Y-DNA R1b and specifically European and West Asian R1b1b2:

Laura Morelli et al., A Comparison of Y-Chromosome Variation in Sardinia and Anatolia Is More Consistent with Cultural Rather than Demic Diffusion of Agriculture. PLoS ONE 2010. Open access.

An excellent critique of Balaresque 2009, totally in the line I was favoring myself.

Most important is maybe fig. 2A, where the use of (novel?) STR marker DYSA7.2, in addition to the usual ones, unveils a clear structure within R1b1b2-M269. I have annotated it for easier visualization:

Click to enlarge

Duality

The already quite obvious Europe-Anatolia (A-B) duality of this haplogroup becomes terribly apparent: two different star-like structures connected by a less clear group (C) centered at the Balcans.

I imagine that sooner than later, someone will come up with a defining SNP for the more than likely Anatolian haplogroup. If I'm correct, with the current nomenclature it should be something like R1b1b2a2. However the root of the whole R1b1b2 haplogroup might also be in that cluster (or is it in C?).

It is surely important to notice that this presumptive R1b1b2a2 haplogroup (at least a clear haplotype star-like structure) also experienced quite apparently a rapid expansion of its own, mostly in West Asia and the Balcans, which is in turn surely related to the expansion of R1b as such through the Mediterranean, Africa (R1b1a) and Central Asia (R1b1b1).

R1b expansion pattern

We may well say that R1b expanded quite dynamically but not with total simple continuity but in colonization "bouts". The first bout is probably best represented by R1b1a scatter in the NE Mediterranean arch (two subclades) and around Central Africa (maybe with a Sudan origin, two subclades too). The second bout is surely a minor one towards Central Asia represented by R1b1b1 (typical of Uyghurs, an odd Chalcolithic founder effect in a previously desert area). The third bout is the spread of R1b1b2-M269 in West Asia and Europe, which represents the bulk of the R1b worldwide in raw numbers.

This third bout is actually two, as is evident in this paper (but was also evident before for those who can "read between lines" at least) but they may have happened in parallel (in which case my annotation above is more strictly correct) or they may have happened sequentially (in which case, lineage B would be R1b1b2a*, except for one of the branches that is actually the root: R1b1b2*).

A quite plausible reconstruction of the spread of R1b (c. 50-30 Ka ago?)
Click to expand

Synthesis

Whatever the case, two things are clear:

1. There is a neat distinction between R1b1b2(xR1b1b2a1) and R1b1b2a1.

2. R1b1b2a1 had its own distinct and fundamentally unique expansion in West Europe, sensu lato.

Also notice that, as happens in previous versions, there are many branches hanging from the R1b1b2a1 central node (modal haplotype also), which appears to contradict the known subhaplogroup structure that only recognizes two branches and which seems to be quite imperfect as of now.


Tempo

As you know I am not any fan of the molecular clock but it's worth mentioning the estimates of this paper for they totally contradict the Neolithic model: the pool of Sardinian and Anatolian R1b1b2 gets an estimate age of 32.6 Ka, the Sardinian one has an age of 27.0 Ka and the Anatolian of 19.6. But the regional ages may be misleading because they include members of both clades, however the overall age should be roughly correct within the molecular clock paradigm.

This would fit with a Gravettian expansion but could also fit with an even older Aurignacian one. It makes some good sense, specially as we are talking of a single expansion that replaced all what was there before, which could only happen at very low population densities, and also because it is a single expansion and not two. It also makes good sense with the likely pattern of expansion of its likely mtDNA companion haplogroup H (also V probably).

As the authors admit, the Magdalenian late glacial recolonization (and noticeable demic expansion) is also within the scope. However I find difficult to explain R1b1b2a1 in Italy within this context, as Italy remained Epigravettian until the very Neolithic. It is also much easier to replace all when there's almost nothing to replace, as was surely the case after the Campanian Ignimbrite supervolcano eruption of c. 40 Ka ago.


Other lineages

The paper is also of interest for other haplogroups such as E, G and J. However I fail to see anything clear surely because of the excessive emphasis in exploring Sardinian-Anatolian connections without a wider scope.


See also: for a completely opposite editorial opinion and likely heated discussion at Dienekes'.