Most archaeologists agree that the ancestors of Native Americans migrated from Asia before the end of the last ice age – around 15,000 years ago. A new study in the American Journal of Human Genetics supports that date and draws a link between the ancestors of Native Americans and the ancestors of the current inhabitants of the Altai region in Central Asia.
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The study – by scientists from the University of Pennsylvania and the Institute of Cytology and Genetics in Russia – used genetic markers in mitochondrial DNA and Y chromosomes to identify the region’s southern inhabitants as having shared a most recent common ancestor with Native Americans approximately 22,000 years ago.
The Y chromosome and mtDNA evidence the researchers used reliably determines ancestry because those genetic sequences aren’t exchanged – like traits such as eye color or sickle-cell anemia – during sexual reproduction.
Instead, mtDNA passes from mother to child and Y chromosomes from father to child. When mutations occur in those codes, they stick. By comparing mutations across the world, scientists can determine who’s related to who.
People with the same mutation are put into a “haplogroup.” Native Americans fit into five mtDNA haplogroups (groups A,B,C,D, and X) and two Y chromosome haplogroups (C and Q). Theodore Schurr – the Penn anthropologist leading the study – and his team detected all five Native American mtDNA haplogroups in Altaians. The match wasn’t perfect however; some subhaplogroups contained markers found only in Native Americans.
On the Y side, Schurr and the research team located 2 markers within the Q haplogroup that “indisputably showed that the MRCA of most Native American Y chromosomes was shared with Southern Altaians.”
The study differs from others that used mtDNA to clarify the origins of Native Americans’ predecessors. Other studies suggest possible regions in Asia, but this is the first to specifically pinpoint a region.
