It is comfortably demonstrable that the material culture of the Beakers emerged from Western Iberia. It's not a global synthesis of a "bunch-o-cultures" and it's not a product of an archaeologically non-existent "unicorn culture". Proper Bell Beaker culture congealed from a slurry of Western Iberian and North African influences.
However, when it comes to R1b, Beakers and Iberia, a lot of people have been getting mired into a seeming paradox (basically this map)>
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| Expansion of R1b (Michael Hammer) |
Here's the fundamental problem with a Danubian R1b expansion (and this holds for the entire R1 family): It is subtly predicated on the demic diffusion rate of a farmer's descendants as they sprawl at a rate of 1 km a year. (Ammerman, Cavalli-Sforza, 1972, also 1984) or again (Pinhasi, Fort, Ammerman, 2005)
At this speed, sufficient time is allowed for branching in which founder twigs have time to move away from the base so that a cline is perceivable. But we know R1b was absolutely not relevant in Europe during the Neolithic and we also know that the Bell Beaker and Corded Ware folks didn't expand at the Neolithic rate of 1 km a year.
Instead, their expansion rate was very rapid and absolutely involved folk movements (again, we are not yet swimming in genetic studies from pre-historic Europe, but at this point it is much more likely that they were exchanging spit rather than attractive pottery and new ideas.)
So what are we seeing in the map above? Well, M269 is probably very old in the Middle East and its immediate periphery. That's about it.
For argument purposes, let's say that the above picture accurately depicts a bona fide, demic cline of R1b movement from the Middle East through Europe. What post-Neolithic phenomenon would explain the picture above? Hold that thought...
Before you imagine metal-age, sword wielding barbarians riding chariots, carefully consider a diffusion rate that would give us a perceivable cline. (in other words, takes-a-lot-of-time-for-mutations-to-occur-so-we-can-see-it-on-a-map)
The movements of R1a and R1b are going to be tough coconuts to crack. Not only did these people move very rapidly, they are both characterized by regional super-lineages which are deceptive to their structure.
It boggles my mind that there haven't been more testing at this point on Beaker cemeteries!