Maciamo, I think this is your narrative. If not let me know and I'll correct.
Why do you think the Beaker Culture was an outgrowth of the Megalithic cultures? In some places, like the Stonehenge area, it looks like the Beaker folks were a new people, with different physical attributes.
Yes, I wrote that. The Beaker Culture was indeed quite different from the Megalithic culture, but also had little to do with the Indo-European Tumulus and subsequent cultures.
The Beaker Culture existed in parallel to the Megalithic culture. It did not replace it. It was more like a wave of new cultural artefacts (introduced by neighbours, such as the R1a Corded-Ware people, or a small group of new immigrants, maybe the G2a people) being traded between various sites belonging to the Megalithic culture.
But I admit that I do not know enough about the Bell Beaker cultures to make a decisive judgement here. The R1b Proto-Celts
may have arrived to Western Europe during the Beaker period. If they did, why didn't we find horses, tumulus, bronze swords and other elements typically linked with the Indo-Europeans ? Why did the Megalithic culture came to a sudden end only around 1200 BCE, when the Urnfield culture started to expand from Germany ?
The Beaker people might have been a small "avant-guard" of Indo-Europeans (R1b or R1a or both), who just traded with the Megalith people, and might have settled in small number among them (without significantly changing the Western European gene pool). But it was not yet the brutal (Proto-)Celtic invasion that would annihilate the older Atlantic culture.
In the absence of DNA tests, the most reliable way to determine ethnicity is still to compare skeletons and cranial features. I wish I had more data on Neolithic and Bronze-Age Europe. If you know any good reference on the matter it is always welcome.
EDIT : I found
this book that explains that Neolithic Britain had collective burial sites with long barrows, and skeletons with long heads (dolichocephalic). During the transition to the Bronze Age, collective burial was replaced by individual burials beneath round barrows, and skulls were round or short (brachycephalic). The mean
cephalic index during the Neolithic was 70.7 (indeed, hyperdolichocephalic and rarely found nowadays), whereas in the Bronze Age it was 78.3 (actually more mesocephalic and similar to the
modern population of Britain). The only true dolichocephals in modern Britain are Highland Scots, suggesting that they are descended more from the Neolithic population.
The question is, how old exactly were these Bronze-Age skeletons ? Did they belong to a few isolated communities of Bell Beakers or was it the norm everywhere in Britain ? I would support the theory that bronze technology was introduced to Western Europe by the Indo-Europeans. The eternal problem is to determine whether technology and crafts were first passed through trade and pacific contact, or if they were the result of an aggressive invasion and massive population change. The fact that the Megalithic culture survived during the Beaker period invalidates the second hypothesis. There were probably Indo-European migrants who came to Britain and Iberia with their bronze technology and beakers, but their presence must have been small or moderate within the local population. The fact that Britain and Iberia (and Scandinavia for that matter) are still much more long-headed than Central Europe is coherent with a substantial leftover of the Neolithic population stratum.
