The middle Holocene was a time when the climate warmed up across North Eurasia, triggering human migrations across great distances, like from Siberia to Europe. Signals of these movements have now been picked up by a new study looking at mtDNA haplogroups C and D.
It appears that European branch C5c1 is more differentiated, as far as two of three sequenced Polish mtDNAs formed a separate branch (C5c1a), defined by a coding region mutation at np 7694. The relatively large amount of internal variation accumulated in the Polish branch of C5c would mean that C5c1 arose in situ in Europe after the arrival of a C5c1 founder mtDNA from southern Siberia, and that C5c1 affiliation is a marker of maternal Siberian ancestry. The phylogeny depicted in Figure S1 provides additional information concerning the entry time of the founder mtDNA – the age of C5c node is estimated as 9.7 (3.17; 16.49) kya when using the sequence variation of the entire genome, and 9.2±4.74 when only synonymous mutations are considered (Table S3). The early presence of mtDNA lineages of eastern Asian ancestry in Europe is further confirmed by the discovery of a N9a haplotype in a Neolithic skeleton from the Szarvas site, located in southeastern Hungary that belonged to the Körös Culture, which appeared in eastern Hungary in the early 8th millennium B.P. .
What the above suggests is that East Eurasian mtDNA lineages don't have a single, recent origin in Europe. They came in dribs and drabs over several millennia, often via Siberia and the Volga-Ural region, with a large proportion arriving during the Neolithic.
Population distribution and frequencies of haplogroup C and its subhaplogroups C1, C5 and C*.
Population distribution and frequencies of haplogroup D and its subhaplogroups D2, D4 and D5.
Derenko M, Malyarchuk B, Grzybowski T, Denisova G, Rogalla U, et al. (2010) Origin and Post-Glacial Dispersal of Mitochondrial DNA Haplogroups C and D in Northern Asia. PLoS ONE 5(12): e15214. doi:10.1371/journal.pone.0015214