A recent study on Plos Genetics (sorry, but I am not able to publish links) seems to confirm Maciamo hypothesis on the origin of basque language and brings new evidence to something that has already been noted: ancient Iberia got much less steppe DNA than Central & Northern Europe.
This findings are consistent with the study published two years ago by PNAS, that pointed that basque people would come more from neolithic settlers than from mesolithic hunter gatherers, as it had been previously thought.
The new study reinforces Maciamo theory that R1b arrived to the Basque Country via small groups of indo-european warriors, that, thanks to their more advanced weapons, could took a ruling status over a much wider neolithic population, whose male lineages went slowly fading from Y-Chromosomes thanks to a bigger reproductive capability (they got more wives and a healthier offspring...); which doesn't correlates with a similar shift on the general genetic structure of the populations as a whole. Thus, R1b hg echoes the higher status of those ruling elites, and its also their more significant legacy.
To me, this situation explains very well the lingustic structure of eastern Iberia and southern France from the Bronce Age to the Iron Age, as non-IE languages were spoken there (Iberian, Basque / Aquitanian). But I still wonder why IE languages did root on central and western Iberia (Celtiberians, Lusitanians, Gallaics, Asturians, Cantabrians...)... interestingly, the remnants examined on the study linked above, proceed from Portugal, where IE speakers are known to have lived.
Moreover, to me it is still a mystery the genesis of celtic dialects in central Iberia. Lusitanian language phylogeny is disputed, and rather considered non-celtic (para-italic, para-germanic or a different branch of IE on its own), a little bit as venetic in ancient Italy. Others say it is celtic in their oldest stages, and some follow Cunliffe in his statement that Iberia is the very cradle of celtic languages (that would have follow an evolution illustrated with Tartessian > Lusitanian > Celtiberian > Old Irish... which seems consistent in time and space with the spread of Bell Beakers). Besides, celtiberian affinity to old Irish (both of them Q-celtic) and the Irish oral tradition point to a possible arrival of Q-Celt to Ireland from Iberia, which doesn't seem coherent, on the other hand, with the genetic differences between the Peninsula and the Isles.
So, to me the questions now to solve the ancient Iberia puzzle would be:
Why did a IE-speaking Iberia ever existed, with such a small steppe peoples introgression?
Which is the filiation of Lusitanian tribes within the IE peoples, and when did they arrived?
Where did Q-Celtic dialects first appeared, and why are they present in Iberia and Ireland?
I advance the following hypothesis:
IE peoples entered Iberia in two waves. The first of them went all their way west and occupied mainly the western part of the peninsula, more adapted to their pastoralist life-style, and less crowded than the Mediterranean and Southern Coasts. They Indo-europeanized the previous neolithic iberians. They spoke a proto-italo-celto-germanic dialect, which developed from Tartessian (with many influxes from Iberian and Phoenicians, which would explain the misterious semitic influence on celtic languages) to Lusitanian, Celtiberian, Gallaic, Asturian, Cantabrian and other IE dialects from western Iberian, some of which fit into the celtic deffinition (Celtiberian and Gallaic and Cantabrian to some extent) and some that don't (Lusitanian, Asturian, Waccaean, Vettonian, Carpetian...). From the Tagus river mouth, the BB culture spread northwards (using commercial networks previously used by "Iberians" (pre-IE neolithic) peoples to spread the Megalithic culture) reaching Britany and Ireland, and carrying old celtic (Q-celtic) languages with them, and some R1b-DF27 along the Atlantic façade of Europe. Interestingly, there is a R1b-DF27 hotspot on the Benelux, next to the Rhine river mouth. This river was the axis of expansion of Bell Beakering into Central Europe, and it was on its very springs, on the Alps, where this Q-celtic peoples / languages met the Hallstatt peoples the first identified as properly celtic. This model would explain the lack of Hallstatt findings on western Iberia and Ireland, the Q-celtic spread and the allegedly semitic background of celtic languages. On central Europe, Q-celtic language joined a larger community of genetically Indoeuropean peoples; and make their way backwards (as R1b-L21; R1b-S28) to the Isles, Gaul, Italy and eastern Iberia; carrying La Tène elements and P-celtic dialects that never reached western Iberia, and only scarcely arrived to Ireland...
What do you think about it?
I know I can have made many mistakes... but celtic languages origin and expansion, specially on Iberia, is still subject of debate... which is your guess about it?