Tuesday, October 6, 2015
Is the R y-chromosome a Hunter-Gatherer Genome
Henn et al presents conclusive evidence that African hunter-gatherer (HG) populations share a number of ancestral lineages including B264*; although they are geographically distinct populations situated among agropastorial groups (1). An interesting finding of Henn et al was the discovery of the Eurasian clade R1b1b1a1a among the Khomani San of South Africa (1).
Henn et al was surprised by this revelation of R-M269 among this Khoisan population. As a result, he interviewed the carries of R1b1b2a1a, and learned that no members of their families had relations with Europeans. The presence of R lineages among HG populations is not new. Wood et al reported Khoisan carriers of R-M269 (2). Bernielle-Lee et al, in their study of the Baka and Bakola pygmies foud the the R1b1* haplogroup (3). These researchers made it clear that the Baka samples clustered closely to Khoisan samples (3).
The most common R haplogroup in Africa is V88. Given the interaction between HG groups and agropastoral groups they live in close proximity too, we would assume that African HG would carry the V88 lineage. Yet, as pointed out above the HG populations carry R-M269 instead of V88 (1-3). The implications of R-M269 among HG populations, and Henn et al’s of shared African HG genome suggest that R-M269 may represent a HG genome.
The low frequency of this Eurasian clade among HG populations may not support this conclusion, the distribution of R-M269 among HG populations needs further research into the origins of the R y-chromosome among African populations.
1. Henn BM, Gignoux CR, Jobin M, Granka JM, Macpherson JM, Kidd JM, Rodríguez-Botigué L, Ramachandran S, Hon L, Brisbin A, Lin AA, Underhill PA, Comas D, Kidd KK, Norman PJ, Parham P, Bustamante CD, Mountain JL, Feldman MW. Hunter-gatherer genomic diversity suggests a southern African origin for modern humans. Proc Natl Acad Sci U S A. 2011 Mar 29;108(13):5154-62. Epub 2011 Mar 7. http://www.pnas.org/content/108/13/5154.full
2. Wood,E.T., Stover,D.A., Ehret,C., Destro-Bisol,G., Spedini,G., McLeod, H., Louie,L., Bamshad,M., Strassmann,B.I., Soodyall,H., Hammer,M.F. 2005. Contrasting patterns of Y-chromosome and mtDNA variation in Africa:evidence for sex-biased demographic processes. European Journal of Human Genetics, 13:867-876.
3. Berniell-Lee G, Calafell F, Bosch E, Heyer E, Sica L, Mouguiama-Daouda P, van der Veen L, Hombert JM, Quintana-Murci L, Comas D. Genetic and demographic implications of the Bantu expansion: insights from human paternal lineages. Mol Biol Evol. 2009 Jul;26(7):1581-9. Epub 2009 Apr 15.http://mbe.oxfordjournals.org/content/26/7/1581.full.pdf