Saturday, October 27, 2012
Y-DNA haplogroup frequency peaks across Europe
The map below comes from a thesis by Russian geneticist Oleg Balanovsky. It shows areas of Europe where certain Y-DNA haplogroups peak at over 35%. Such zones cover most of the continent, which I think is a sign that patrilineality and paternal founder effects have had a significant role in the formation of the modern European gene pool.
Indeed, continental Europe is basically dominated by just two haplogroups: R1a and R1b. The >35% R1a zone stretches from Central Europe to the Volga-Ural region...and meets a couple of >35% R1b zones at both ends. This might seem a little odd at first, but not if we suppose that R1b spread from present-day Anatolia and/or Iran both to the west and east, but not directly north due to the Black Sea and Caucasus Mountains acting as major barriers to human dispersals.
Moreover, it would appear that R1a already occupied a large area of Eurasia before the main R1b expansions across or even into Europe. This is suggested by the map above as well as ancient DNA results, which show the presence of R1a in Late Neolithic and Bronze Age remains all the way from present-day Germany to South Siberia. If that wasn't the case, then it's difficult to explain the paucity of R1b and lack of R1b SNP diversity in modern Ukrainians and Russians, and its complete absence in remains from steppe kurgans tested to date, which are almost totally dominated by R1a.
Balanovsky Oleg P., Variability of gene pool in space and time: Data synthesis, genogeography, mitochondrial DNA and Y-chromosome. Dissertation for the degree of Doctor of Science. 2012