I would say so too. Only in Bronze age with development of bronze axe, the farmers were able to chop/de-wood heavy northern forests on industrial scale, clearing the land for white fields. Till then copper axe was too soft for the job. Also breeding new varieties of wheat, like rye, for northern climate was paramount for farmers to spread north successfully. The process was long enough to allow natives of I and R1a varieties to slowly adapt to farming, hence bigger proportions of WHG when going north.
Most population movements, that we know of, happened from North to South and West to East. We should conclude that these movements elevated WHG and ANE level somewhat. Deep South of Europe is at around 10% level of WHG, so how much was there before many invasions, 5%?
Fan with math:
Let's say population of Italy is 5 million at the end of Roman Empire (at 5% of WHG). Germanic tribes of 500 thousand people (WHG at 40%), invaded Italy. I think math goes like this: (5*10+0.5*40)/10.5=8.19% of WHG for all mixed population of Italy, giving enough time for mixing.
It is not an accurate example by no means, but it illustrates how numbers of WHG can go up every time there was an invasion from North or North East, and how much effort it would take to make a dent.
I would look for ancient "Roman" village with any DNA to sequence, before the rise of the Rome. As long as the village could be identified as Latin, and older the better. Later people started mixing a lot to be sure of results.
Those figures for the Ashkenazim don't seem to support very much admixture in central or eastern Europe with "European" women. I would have a hard time believing that the WHG component wasn't present in the Rhineland at the time of the Crusades at figures close to what they are today. If, and to what extent admixture occurred, it looks as if the majority of it would have had to have been admixture with Greek and/or southernItalian/Sicilian and and/or Balkan type populations of the Iron Age.
I'm getting confused with all of the data floating around...and accepting other people's statements without checking for myself, for which I apologize. Although the numbers for ANE are all close, Sicilians don't have the highest ANE of the Italian populations. It's actually the Tuscans, which means this is one of those situations where the components are not on the predicted cline. (I'll also correct the record on the original post.)
Here are the actual proportions for the ten tested populations:
EEF/WHG/ANE:
Bergamo: .715, .177, .108
Tuscan: .746, .136, .118
Sicilian: .903, 0, .097
Sardinians: .817, .175, .008
The virtual lack of ANE in Sardinians is striking, but in keeping with all the ADMIXTURE analyses run in the past on them which show no "West Asian". At the same time, the WHG is as high as Bergamo, or about 18%. The question for me is, were there WHG's on the island who were absorbed by incoming EEF (who, of course, like all EEF people, also carry another hidden 20% or so WHG?) or did it arrive later. Jean Manco is on record as saying that there were no actual H/G settlements on the island, and the few traces found were transitory camp sites. She then proposes that the yDNA I2a and E1b1b on the island comes from young clades that arrived from the Balkans in the Copper Age. You guys would know more about the yDNA than I do, but if it did come from the Balkans from the period after the collapse of "Old Europe" and the movement into the area of Indo-European speaking steppe people, shouldn't they also have carried some ANE into Sardinia? Not even mentioning they'd bring some sort of PIE. I'm going to have to research the dates for these movements. Another possibility is that it came by way of Spain and then the southern French coast. There is another very old yDNA 12a strain in western Europe, and E1b1b was also found, of course. Also, from the northern Mediterranean into Sardinia is far easier than approaching it from the east.
As for when I2a became involved with agriculture and admixed with the EEF people, I think one good bet would be the Balkans. There was a paper that found evidence that there was admixture between the female EEF and the male HG/s within a couple of generations. Perhaps some of the I2a H/G's returned the complement and became part of the farming community. This wouldn't have impacted any H/G YDNA I further north for a long time.
I can't wait until we get the results from the Bean project. They're studying not only the Mesolithic but also the Neolithic peoples of both the Balkans and Anatolia. I'm very interested to see how different the people in Thessaly, for example, could have been from the people in NW Anatolia. I do hope they're also testing people from further east in Anatolia, near the Zagros mountains, and also down the coast a bit to northern Syria.
Perhaps we'll be surprised and there is another HG group which has to be taken into consideration. A study by a Greek academic, which was posted by Dienekes, shows no mtdna U whatsoever, not even in the Mesolithic samples. And the mtDNA she found is what we have become accustomed to call "European" or at least "Neolithic" dna: J1b, H, lots of K, and even X. What will that do to all of our calculations?
And, will we find that the EEF population didn't mostly come from the Near East or the very southern Levant, as we all have been postulating, but came from southern and south eastern European Mesolithic populations with only a small input from further south or east. Or, as another possibility, as Hunter Gatherers from Siberia to the gates of Europe weren't that different from one another, as the AF finds may show, perhaps the HGs, soon to be farmers of the European southeast, were not very different from the people in Anatolia. Who knows...I'm sure it will be a surprise.
One final thought before I fall asleep over the computer...the Bollingino study that was cited above made some pretty broad claims based on one incidence of HG's and EEF sharing time and space in central Europe. I don't know if that finding can be extrapolated to the situation over all of Europe, i.e. that there were a lot of HG's who remained basically in place, tending to their fishing and ignoring the farmers tilling the good loess soils. Actually, they were'nt totally ignoring each other. The mtDNA data doesn't show any EEF females being absorbed into the HG community, but a good number of the WHG mtDNA lines did show up among the members of the Neolithic farming community. So, it's those U mtDNA signatures that show that admixture was indeed taking place.
The big question is, what was the Y signature of these EEF men...G2a, and some I2a, doubtless, and if they were happily outbreeding all the HG males, you would have a big increase in G2a for example. So what happened? Are R1b and R1a, ANE carriers for the sake of the argument, responsible for the decrease in the EEF males lineages? They certainly didn't replace the autosomal make-up of these people however. I read somewhere that the median in Europe is over 56 for EEF.
And here I was thinking that some good ancient DNA would clear everything up? LOL