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Original Source Article
What was the research project?
The research project was an investigation into the initial migration to the Americas from a group descended from a Siberian population.
Were they testing a hypothesis or doing discovery science?
This was discover science working in conjunction with a research question about Native Americans’ migration from Siberia across the Bering Land Bridge. While most experts agree that this occurred about 14.6 ka (14,600 years ago), there is much debate concerning how many migrations occurred, the total number of migrants, and the date of their last contact was with Siberian ancestors. This paper tries to answer these questions using genomic evidence.
What genomic technology was used in the project?
This study used SNP chip genotype data to measure differences among the present Native American population and candidate ancestor populations. This is another example of a completely dry lab experiment. All the data used was freely available and already housed in a public database. This summary mentions that three different methods were used when dating the Native American’s divergence from Siberian ancestors, tho they do not say what those three methods were.
What was the take home message?
The take-home message was a time line of Native American migration and divergence from ancient Siberian populations (Figure 1.). The population that would eventually migrate to, and populate, the Americas split from a group of Siberian ancestors about 23 ka - 20 ka. After this event, there was a period of isolation lasting about 8,000 years before the population split again into Athabascan/North Amerindian who would inhabit North America and the Southern Amerindians who populated Central and South America. This is study also corroborates the single-migration theory. They also found that the gene flow between East Asian/Inuit populations and the Athabascan/Amerindians happened post-migration.
Figure 1. Migration pattern of Athabascans and Amerindian populations. The genomic evidence points to a single migration event around 23 ka when a population left the Siberian ancestral population.
What is your evaluation of the project?
I found the study and its conclusions interesting. However, with such an abbreviated methods section it is hard to confirm the validity of the findings. A more thorough reading of the initial paper is necessary to build the credibility of their findings.
Rag haven, M et al. 2015. Genomic evidence for the Pleistocene and recent population history of Native Americans. Science [Internet]. [cited 28 Jan 2016]; 349(6250): 841. Available from: http://science.sciencemag.org/content/349/6250/aab3884
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