The big new paper on European origins is out (by Wolfgang Haak, Iosif Lazaridis, Nick Patterson, David Reich, etc) .
The Corded Ware population is quite different from the preceding Neolithic farmers: it is about 75% descended from a Yamnaya-like population (the Yamnaya being steppe herders from the Ukraine and thereabouts). The Yamnaya themselves are another fusion product: they’re a mix of farmers from the Middle East (a different population than the one that originally settled Europe, something like Armenians) and a population similar to ancient hunter-gatherers from Russia (somewhat like ancient Karelians). This population also introduced R1a and R1b chromosomes into Europe, now extremely common.
In northern Europe, the newcomers didn’t tax the neolithic farmers: mostly, they killed them. Razib Khan compares this to the original Mongol plan ( kill them, kill them all), before that Khitan bureaucrat explained the joys of taxation. In the Corded Ware/Single Grave/Battleaxe culture, there’s no sign that the farmers are around as serfs: there are almost no buildings, almost no sign of agriculture. Jim, comment on this.
The Karelian-like population is mostly from further east than Samara: the guys that domesticated the horse.
The Karelian-like poulation conquered the Armenian-like farmers: they account for about half the autosomal ancestry of the Yamnaya, but far more of the Y chromosomes.
it would be interesting to see if the Yamnaya picked up neolithic farmers ancestry through the female line: could you look at X-chromosomes?
In places like Italy, people are autosomally mostly neolithic farmers while the old Neolithic-farmer y-chromsomes are almost gone. Conquest, rather than extermination: younger sons go forth to conquer again. Some of the old Y chromosomes lingered in the hills – a bit like Vlachs after the fall of the Roman Empire.
Did the ur-IndoEuropeans have the European lactose-tolerance mutation? Probably. And they had the common CF mutations, too.
Archaeologists should read more Conan: Robert E. Howard was way closer to the mark than they were or are. Even good guys like David Anthony were influenced: but I’ll bet he’s over that now.