July 16, 2008

Y chromosomes and Athapaskans

From the EurekAlert release:
The new findings reinforce the hypothesis that the Athapaskan migration involved a relatively small group that nonetheless was very successful at assimilating and intermixing with native groups already living in the southwest. The newcomers were so influential that the Athapaskan language family now dominates many parts of the Southwest. Now called Apacheans, the Navajo and Apache descendants of the early migrants are dispersed throughout the central Southwest and speak languages closely related to the Chipewyan, an Athapaskan language found in the subarctic.


Other patterns emerged from the Y chromosome analysis. One genetic signature associated with European males was detected in native males throughout North America, but was found at the highest frequency in groups living nearest to Hudson Bay, where trade between Europeans and the region's indigenous peoples was established in the early 17th century.

From the paper:
Gene map interpolations (Fig. 2A–C) indicate that the frequency of haplogroup Q is highest in Southwestern North America/Mesoamerica. The frequency of haplogroup C is highest in Northwestern North America and the frequency of haplogroup R, the presence of which is attributed to European admixture, reaches its maximum in Northeastern North America. In total, 73% percent of the populations analyzed exhibited haplogroup R, which ranges in frequency from 4 to 88% (Table 1).


Y chromosome haplogroup C is observed at a moderate frequency in the Subarctic Athapaskan groups and at a low frequency in the Navajo and Apache, but is otherwise absent from the Southwest. Nearly all Navajo and Apache Y chromosomes within haplogroup C belong to a specific, well-defined subclade (Zegura et al., 2004). Hence, it is likely that ancestral Subarctic Athapaskan speakers provided the source for Y chromosome haplogroup C as well as the mtDNA A2a subclade in Apachean groups.
However, Apachean groups cluster with other Southwest and Mesoamerican groups in the principal coordinates analysis, rather than with Athapaskans from the Subarctic. This suggests that the majority of non-C Y chromosomes in the Navajo and Apache were contributed by non-Athapaskan populations in the Southwest, which mirrors the presence in the Apachean of mtDNA lineages belonging to haplogroups B and C.

Wikipedia on Athapaskan languages.

American Journal of Physical Anthropology

Distribution of Y chromosomes among native North Americans: A study of Athapaskan population history

Ripan Singh Malhi et al.


In this study, 231 Y chromosomes from 12 populations were typed for four diagnostic single nucleotide polymorphisms (SNPs) to determine haplogroup membership and 43 Y chromosomes from three of these populations were typed for eight short tandem repeats (STRs) to determine haplotypes. These data were combined with previously published data, amounting to 724 Y chromosomes from 26 populations in North America, and analyzed to investigate the geographic distribution of Y chromosomes among native North Americans and to test the Southern Athapaskan migration hypothesis. The results suggest that European admixture has significantly altered the distribution of Y chromosomes in North America and because of this caution should be taken when inferring prehistoric population events in North America using Y chromosome data alone. However, consistent with studies of other genetic systems, we are still able to identify close relationships among Y chromosomes in Athapaskans from the Subarctic and the Southwest, suggesting that a small number of proto-Apachean migrants from the Subarctic founded the Southwest Athapaskan populations.



pconroy said...

but was found at the highest frequency in groups living nearest to Hudson Bay, where trade between Europeans and the region's indigenous peoples was established in the early 17th century.

While there were contacts between the Hudson Bay Company and native fur trappers, it would be interesting to see more information on the actual R haplotypes found, as there was also contact with the Basques prior to that, and the Vikings before that, and the Irish before that - all of these populations are majority R...

terryt said...

And it shows once more that language is not necessarily closely correlated with haplogroups. And immigrants ultimately mix with their neighbours.

I agree that Irish, Vikings and Basques are as likely a source of R as are more recent European arrivals.