The question is, where did Europeans come from? There have been a number of hypotheses, ranging from in-situ evolution from Neanderthal ancestors (mostly not), directly from the earlier modern human settlers, from Near Eastern farmers, from Indo-European steppe horsemen… and from some of the above, or all of the above. Or something stranger than we have imagined, or perhaps can imagine.
Looks complicated. So let me talk about one strand in the tapestry: the Impressed Ware Culture, characterized by a distinctive kind of pottery whose surfaces were decorated with zoned patterns before firing, often by the shell of the Mediterranean cockle, Cardium.
These people had pottery and polished stone tools, cultivated wheat, barley, and legumes, raised sheep, goats, cattle and pigs. They were the first farmers along most of Europe’s Mediterranean coast.
These artifacts show up first in Epirus and Corfu, around 6400-6200 BC. From there, they spread rapidly around the Adriatic, to Calabria, Sicily and Sardinia, Provence, Catalonia, and the Atlantic coast of Portugal. Expansion from Greece to Portugal took little more than 500 years.
Almost all of the males in these cultures had G2a Y-chromosomes haplotypes. Today G2a is much rarer: you tend to find it in mountainous regions, and in Mediterranean islands such as Sardinia and Corsica. It seems that Sardinians are the closest extant population. Ötzi’s (the famous frozen guy) Y chromosome fell into this category ( G2a2b), and his autosomal genes were close to modern Sardinians, although a bit more different from other Europeans than current Sardinians.
There is a genetic component, probably West Asian, that is found generally in Europeans, but not in Sardinians or Basques. It seems likely that this component is something that arrived later than the original farmers of Mediterranean Europe. Sardinians and Basques look like a mixture of two populations, one from the Middle East ( the Middle East of the past, not exactly like the Middle East today) and a generic European component that may come from the earlier hunter-gatherers of Europe – although there are problems with that explanation , too: it’s hard to make the mtDNA data fit.