July 01, 2011

Y chromosomes from Afghanistan

Someone from dna-forums was kind enough to send me the haplogroup estimates for this collection of haplotypes; the modal haplogroup in both North and South Afghanistan seems to be R1a with estimates ages that are consistent with those of the Underhill et al. study. (in "evolutionary mutation rate" years/25 years per genration: 12ky south, 7.8ky north, corresponding to 4.7/3ky using germline rate, correction factor, and 31.5 years/generation). I repeat what I wrote in the forum:
While I don't put much faith in Y-STR estimates due to the huge confidence intervals associated with them once all sources of uncertainty are factored in, these are comparable to the Underhill ones, and they seem to establish that (a) Afghanistan is not really remarkable in terms of Y-STR variation, (B) R1a (or at least the likely R1a1a forming the bulk of these) is a Neolithic-to-Bronze Age phenomenon, and (c) if the North/South difference is real, then it fits well with the highest estimated age in India-Pakistan-Nepal and a diminution towards Central Asia.
It would be great to see a study of Afghans with a detailed suite of Y-SNP markers to see how they fit in the Eurasian landscape. Hopefully a combination of more phylogenetic resolution and ancient DNA will help us better understand the ancient distribution and dispersals of the R1a haplogroup.

Somewhat related: some thoughts on Indo-Iranians.

Legal Medicine Volume 13, Issue 2, Pages 103-108 (March 2011)

Y-STR profiling in two Afghanistan populations

Harlette Lacauab et al.


Afghanistan’s unique geostrategic position in Eurasia has historically attracted commerce, conflict and conquest to the region. It was also an important stop along the Silk Road, connecting the far eastern civilizations with the western world. Nevertheless, limited genetic studies have been performed in Afghan populations. In this study, 17 Y-chromosomal short tandem repeat (Y-STR) loci were typed to evaluate their forensic and population genetic applications in 189 unrelated Afghan males geographically partitioned along the Hindu Kush Mountain range into north (N=44) and south (N=145) populations. North Afghanistan (0.9734, 0.9905) exhibits higher haplotype diversity than south Afghanistan (0.9408, 0.9813) at both the minimal 9-loci and 17-loci Yfiler haplotypes, respectively. The overall haplotype diversity for both Afghan populations at 17 Y-STR loci is 0.9850 and the corresponding value for the minimal 9-loci haplotypes is 0.9487. A query using of the most frequent Afghan Yfiler haplotype (7.98%) against the worldwide Y-STR haplotype reference database (YHRD) returned no profile match, indicating a high power of discrimination with 17 Y-STR loci. A median-joining network based on 15 Y-STR loci displays limited haplotype sharing between the two Afghan populations, possibly due to the Hindu Kush Mountain range serving as a natural barrier to gene flow between the two regions.


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