Here is a new paper by Daniel Gómez-Sánchez and co-workers. They tested 19 mitochondrial sequences from the Burgos region in Castile and León, northern Spain, all dating from the late Copper Age (2050 to 2500 BCE).
The authors note the heterogeneity of mt-haplogroups compared to other Neolithic and Chalcolithic sites around Europe, mostly from Germany. Obviously mitochondrial diversity is so high in Europe and it is meaningless to try to find patterns from tiny sample sizes like that. Comparisons wouldn't be relevant with less than 500 samples for just one geographic area in one specific period ranging no more than a five centuries.
What I find more interesting to note here is the continuity of Neolithic lineages, even if proportions between haplogroups vary widely from one region to another due to the small sampling size. There were two great population shifts in European prehistory: the first one brought about by the diffusion of agriculture by Near Eastern farmers, and the second one caused by the Bronze Age invasions of Indo-European-speaking steppe people.
We have long debated on this forum (e.g. here and here) whether :
a) the first Indo-European R1b people were the Bell Beaker folks themselves, a hypothesis that a lot of people supported since Lee et al. 2012 announced that they identified two R1b individuals from a Bell Beaker site in eastern Germany dating from c. 2500 BCE.
b) or (as I suggested), the Bell Beaker culture was directly descended from the Neolithic (Megalithic) cultures of Western Europe, and was invaded and destroyed by the Indo-Europeans, who moved from Central Europe (2500 BCE) toward Atlantic Europe (2200 to 1800 BCE).
This new paper is interesting because the samples span exactly the Bell Beaker period in Spain and therefore provide valuable evidence on the matter. Not all regions of Iberia yielded Beaker pottery, but Castile and Leon was definitely a hotspot, and in fact the oldest (along with central Portugal) and the single largest Bell Beaker region in Iberia. This is lucky as it means that those samples should be highly representative of the original Bell Beaker folks.
Since no Y-DNA sample was tested, we have to rely on mtDNA as a proxy for the advance of steppe people. I have explained here which mt-haplogroups I believe are most strongly associated with the spread of the R1b and R1a branches of Bronze Age Indo-Europeans.
According to the map of this period I made 5 years ago, R1b should not yet have reached Iberia in the period 2500-2000 BCE. The Pyrenees acted a natural barrier that considerably slowed down the progression of R1b toward Iberia. R1b mostly likely spread very late during the Bronze Age in Iberia, between 1800 and 1200 BCE. So none of the mtDNA samples should be of steppe origin.
And this is exactly what we see. No haplogroup I, J1b1a, U2, U4, U5a1a or W. Unfortunately they didn't test the H and K subclades, so we can't know for sure for these. But the proportions are far more representative of a Neolithic population, with high percentages of H, K and X2, than of a Bronze Age steppe population, which would have comparatively much lower levels of these three haplogroups. The strong presence of T2b, U3 and X2 are all signs of a typical Neolithic European population. There isn't the slightest element that could hint that R1b was already presence in the region during the Bell Beaker period.
The authors note the heterogeneity of mt-haplogroups compared to other Neolithic and Chalcolithic sites around Europe, mostly from Germany. Obviously mitochondrial diversity is so high in Europe and it is meaningless to try to find patterns from tiny sample sizes like that. Comparisons wouldn't be relevant with less than 500 samples for just one geographic area in one specific period ranging no more than a five centuries.
What I find more interesting to note here is the continuity of Neolithic lineages, even if proportions between haplogroups vary widely from one region to another due to the small sampling size. There were two great population shifts in European prehistory: the first one brought about by the diffusion of agriculture by Near Eastern farmers, and the second one caused by the Bronze Age invasions of Indo-European-speaking steppe people.
We have long debated on this forum (e.g. here and here) whether :
a) the first Indo-European R1b people were the Bell Beaker folks themselves, a hypothesis that a lot of people supported since Lee et al. 2012 announced that they identified two R1b individuals from a Bell Beaker site in eastern Germany dating from c. 2500 BCE.
b) or (as I suggested), the Bell Beaker culture was directly descended from the Neolithic (Megalithic) cultures of Western Europe, and was invaded and destroyed by the Indo-Europeans, who moved from Central Europe (2500 BCE) toward Atlantic Europe (2200 to 1800 BCE).
This new paper is interesting because the samples span exactly the Bell Beaker period in Spain and therefore provide valuable evidence on the matter. Not all regions of Iberia yielded Beaker pottery, but Castile and Leon was definitely a hotspot, and in fact the oldest (along with central Portugal) and the single largest Bell Beaker region in Iberia. This is lucky as it means that those samples should be highly representative of the original Bell Beaker folks.
Since no Y-DNA sample was tested, we have to rely on mtDNA as a proxy for the advance of steppe people. I have explained here which mt-haplogroups I believe are most strongly associated with the spread of the R1b and R1a branches of Bronze Age Indo-Europeans.
According to the map of this period I made 5 years ago, R1b should not yet have reached Iberia in the period 2500-2000 BCE. The Pyrenees acted a natural barrier that considerably slowed down the progression of R1b toward Iberia. R1b mostly likely spread very late during the Bronze Age in Iberia, between 1800 and 1200 BCE. So none of the mtDNA samples should be of steppe origin.
And this is exactly what we see. No haplogroup I, J1b1a, U2, U4, U5a1a or W. Unfortunately they didn't test the H and K subclades, so we can't know for sure for these. But the proportions are far more representative of a Neolithic population, with high percentages of H, K and X2, than of a Bronze Age steppe population, which would have comparatively much lower levels of these three haplogroups. The strong presence of T2b, U3 and X2 are all signs of a typical Neolithic European population. There isn't the slightest element that could hint that R1b was already presence in the region during the Bell Beaker period.
