Sometimes I wonder how researchers pick and choose the ancient samples that they test for DNA. Very often they don't seem like to be from the most interesting places and periods to further our understanding of European prehistory.
Now that Neolithic Y-DNA and autosomal DNA has been successfully retrieved several times, it is surprising that some researchers would decide to test exclusively mtDNA. Now that we have plenty of mtDNA tested from all countries and periods, it is practically useless to test more of it, especially from regions and periods that were already tested. MtDNA is generally not very useful for population genetics within Europe. What we want is Y-DNA and autosomal DNA, but not samples from any location or time frame. Here is a list of what I believe to be the most essential tests to be conducted to confirm or disprove the hottest theories of the moment, and shed light on the darkest mysteries of European prehistory.
1. Mesolithic Y-DNA from Britain, Ireland, Scandinavia, the Benelux and northern France
We don't have any Mesolithic Y-DNA at present, but it is widely assumed that pre-Neolithic Europeans belonged to Y-haplogroup I. The homogeneity of their mtDNA (U4, U5) suggests that we should indeed expect a single macro-haplogroup like hg I all over Europe. Haplogroup I2a1 was found on a Neolithic site in southern France, which suggests that this was, like today, the main subclade of I in Mediterranean Europe, probably as far north as the Alps and the Carpathians. The big unknown is northern Europe, and especially north-west Europe.
It is also widely assumed that Mesolithic Scandinavia belonged to haplogroup I1, but the estimation of the age of I1 varies widely, and it would be interesting to confirm once and for all when I1 really arose. Considering the numerous defining mutations of I1, shall we expect to find a lot of "pre-I1" in Mesolithic Scandinavia ? And when would I1 have replaced all the other pre-I1 lineages then ? In the early or late Mesolithic ? In the Neolithic or Bronze Age ?
The most interesting would be to see what lineages were present in Ireland, Britain, northern France and the Low Countries during the Mesolithic. Nowadays I1, I2a1 (former I2a) and I2a2 (former I2b) are all present there. As I1 and I2a2 are thought to be late arrivals from Iron Age Celtic and Germanic people, that would leave only I2a1. But that haplogroup appears to young to have expanded all over Western and Mediterranean Europe by the Mesolithic period. Therefore, the most likely candidates is the older I2*, or even I* or IJ. That would mean that Mesolithic lineages of Northwest Europe would have all but disappeared today, which is not at all improbable considering that I2a1 only survived in the most isolated parts of Southwest Europe (Pyrenees, Sardinia).
2. Eye and hair pigmentation genes from Mesolithic northern Europe
This is something that a lot of people are interested in. Where do blue eyes and blond or red hair come from ? Were these traits already present in Mesolithic North Europeans ? Everywhere or only in Scandinavia ? I would be inclined to think that both blue eyes and blond hair came from Northeast Europe, especially European Russia, and that the R1a steppe people brought them to the Baltic region with the expansion of the Corded Ware culture (and later steppe invasions). The biggest question for me is for red hair, because it now peaks in Northwest Europe (in the old Celto-Germanic world), but it also found in isolated parts of Russia near the Urals, and even in pockets of Central and South Asia. I think that the genes were brought by R1b people during the Bronze Age, but they could as well have come from Mesolithic Northwest European. I believe that both the Bronze Age R1a and R1b people had blue eyes, although at higher frequency among European R1a tribes.
3. Y-DNA from various early Bronze Age cultures
We have surprisingly little Bronze Age Y-DNA at present. So far, we only have R1a samples from the Corded Ware Culture, and I2a2, R1a and R1b samples from the Urnfield Culture.
It would be most interesting to have results from Western and Central Europe (around 2000 BCE), the Pontic-Caspian Steppes (southern Yamna Culture), North Caucasus (esp. Maykop Culture), as well as the Middle East, Anatolia and Greece (notably Minoan Crete). Besides R1a being associated with the Corded Ware and Andronovo cultures, I expect to find R1b associated with the southern Pontic steppe cultures, then of the Danubian, Alpine and Western European Bronze Age elite. J2 would mark a southern Bronze Age expansion from the highlands of Anatolia, Mesopotamia and the Caucasus towards the lowland Middle East (as far south as the Israel/Palestine/Jordan), Cyprus, Greece and Italy.
4. Neolithic Y-DNA from the Balkans, Anatolia and Levant.
We already have Neolithic Y-DNA from Italy, France, Spain and southern Germany, but nothing from the places where it all started. I expect to find haplogroups G, T and E1b1b dominating the Neolithic landscape in the Levant and Anatolia, but I still have my doubts about the Balkans, where E1b1b is vastly more frequent today than G2a. I wonder if the cultures of "Old Europe" (those that sprang from the Thessalian Neolithic) were not predominantly created by a small group of E1b1b (mostly E-V13) settlers that expanded exponentially and blended with the indigenous Mesolithic I2a1 people. That would explain the predominance of these two haplogroups in the region today. The J2 in the Balkans would be the result of later waves of immigrants from Greece and/or Anatolia starting from Bronze Age until the Ottoman period).
The way I see it is that the Mesolithic I2a1 acquired agriculture techniques from Neolithic farmers in Greece and Albania, then were the ones mostly responsible for the spread of agriculture in the Danubian basin itself. That would explain why I2a1 survived much better the Neolithic in Southeast Europe than in Southwest Europe. In any case, based on the case of Sardinia and on mtDNA from Megalithic Europe, it really seems that I2a1 people did blend well with Near Eastern farmers.
Now that Neolithic Y-DNA and autosomal DNA has been successfully retrieved several times, it is surprising that some researchers would decide to test exclusively mtDNA. Now that we have plenty of mtDNA tested from all countries and periods, it is practically useless to test more of it, especially from regions and periods that were already tested. MtDNA is generally not very useful for population genetics within Europe. What we want is Y-DNA and autosomal DNA, but not samples from any location or time frame. Here is a list of what I believe to be the most essential tests to be conducted to confirm or disprove the hottest theories of the moment, and shed light on the darkest mysteries of European prehistory.
1. Mesolithic Y-DNA from Britain, Ireland, Scandinavia, the Benelux and northern France
We don't have any Mesolithic Y-DNA at present, but it is widely assumed that pre-Neolithic Europeans belonged to Y-haplogroup I. The homogeneity of their mtDNA (U4, U5) suggests that we should indeed expect a single macro-haplogroup like hg I all over Europe. Haplogroup I2a1 was found on a Neolithic site in southern France, which suggests that this was, like today, the main subclade of I in Mediterranean Europe, probably as far north as the Alps and the Carpathians. The big unknown is northern Europe, and especially north-west Europe.
It is also widely assumed that Mesolithic Scandinavia belonged to haplogroup I1, but the estimation of the age of I1 varies widely, and it would be interesting to confirm once and for all when I1 really arose. Considering the numerous defining mutations of I1, shall we expect to find a lot of "pre-I1" in Mesolithic Scandinavia ? And when would I1 have replaced all the other pre-I1 lineages then ? In the early or late Mesolithic ? In the Neolithic or Bronze Age ?
The most interesting would be to see what lineages were present in Ireland, Britain, northern France and the Low Countries during the Mesolithic. Nowadays I1, I2a1 (former I2a) and I2a2 (former I2b) are all present there. As I1 and I2a2 are thought to be late arrivals from Iron Age Celtic and Germanic people, that would leave only I2a1. But that haplogroup appears to young to have expanded all over Western and Mediterranean Europe by the Mesolithic period. Therefore, the most likely candidates is the older I2*, or even I* or IJ. That would mean that Mesolithic lineages of Northwest Europe would have all but disappeared today, which is not at all improbable considering that I2a1 only survived in the most isolated parts of Southwest Europe (Pyrenees, Sardinia).
2. Eye and hair pigmentation genes from Mesolithic northern Europe
This is something that a lot of people are interested in. Where do blue eyes and blond or red hair come from ? Were these traits already present in Mesolithic North Europeans ? Everywhere or only in Scandinavia ? I would be inclined to think that both blue eyes and blond hair came from Northeast Europe, especially European Russia, and that the R1a steppe people brought them to the Baltic region with the expansion of the Corded Ware culture (and later steppe invasions). The biggest question for me is for red hair, because it now peaks in Northwest Europe (in the old Celto-Germanic world), but it also found in isolated parts of Russia near the Urals, and even in pockets of Central and South Asia. I think that the genes were brought by R1b people during the Bronze Age, but they could as well have come from Mesolithic Northwest European. I believe that both the Bronze Age R1a and R1b people had blue eyes, although at higher frequency among European R1a tribes.
3. Y-DNA from various early Bronze Age cultures
We have surprisingly little Bronze Age Y-DNA at present. So far, we only have R1a samples from the Corded Ware Culture, and I2a2, R1a and R1b samples from the Urnfield Culture.
It would be most interesting to have results from Western and Central Europe (around 2000 BCE), the Pontic-Caspian Steppes (southern Yamna Culture), North Caucasus (esp. Maykop Culture), as well as the Middle East, Anatolia and Greece (notably Minoan Crete). Besides R1a being associated with the Corded Ware and Andronovo cultures, I expect to find R1b associated with the southern Pontic steppe cultures, then of the Danubian, Alpine and Western European Bronze Age elite. J2 would mark a southern Bronze Age expansion from the highlands of Anatolia, Mesopotamia and the Caucasus towards the lowland Middle East (as far south as the Israel/Palestine/Jordan), Cyprus, Greece and Italy.
4. Neolithic Y-DNA from the Balkans, Anatolia and Levant.
We already have Neolithic Y-DNA from Italy, France, Spain and southern Germany, but nothing from the places where it all started. I expect to find haplogroups G, T and E1b1b dominating the Neolithic landscape in the Levant and Anatolia, but I still have my doubts about the Balkans, where E1b1b is vastly more frequent today than G2a. I wonder if the cultures of "Old Europe" (those that sprang from the Thessalian Neolithic) were not predominantly created by a small group of E1b1b (mostly E-V13) settlers that expanded exponentially and blended with the indigenous Mesolithic I2a1 people. That would explain the predominance of these two haplogroups in the region today. The J2 in the Balkans would be the result of later waves of immigrants from Greece and/or Anatolia starting from Bronze Age until the Ottoman period).
The way I see it is that the Mesolithic I2a1 acquired agriculture techniques from Neolithic farmers in Greece and Albania, then were the ones mostly responsible for the spread of agriculture in the Danubian basin itself. That would explain why I2a1 survived much better the Neolithic in Southeast Europe than in Southwest Europe. In any case, based on the case of Sardinia and on mtDNA from Megalithic Europe, it really seems that I2a1 people did blend well with Near Eastern farmers.