Genes Shed Light on Our Origins

Genes Shed Light on Our Origins

Now that researchers have the technology to look at hundreds of thousands of genetic markers, they’re uncovering new clues about human origins and gaining fresh insights into early patterns of human migration.

A study of human genetic variation conducted by researchers at the University of Michigan and the National Institute on Aging supports the idea that anatomically modern humans originated in Africa, then spread to the Middle East, Europe and Asia, the Pacific Islands, and finally to the Americas.

The study also bolsters the notion of “serial founder effects,” meaning that as people began migrating outward from Africa sometime on the order of 100,000 years ago, each successive wave of migrants carried a subset of the genetic variation held by previous groups. Human genetic diversity decreases as distance from Africa—the cradle of humanity—increases.

“Diversity has been eroded through the migration process,” says study co-author Noah Rosenberg, an assistant professor of biostatistics and assistant research professor at the UM Life Sciences Institute.

Rosenberg and his colleagues characterized more than 500,000 DNA markers on the human genome and examined genetic variations across 29 populations on five continents. Their research is the largest and most detailed analysis of worldwide human genetic variation
produced to date.

“This data set is so rich,” says co–first author Paul Scheet, a postdoctoral fellow in the Department of Biostatistics. The study demonstrates that in many cases it’s possible to use genomics to trace a person’s ancestry to an individual population within a geographic region. It also offers new clues to the genetic variants that can trigger various diseases, and new information that can facilitate the search for disease-causing genes in different populations. The study appeared in the February 21 issue of Nature.

—Laura Bailey

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