Tree of inferred relationships of present-day and ancient humans considered, including (a) the ancient Ust-Ishim sample, and (b) the ancient Europeans samples. (Image courtesy authors)

Roughly 45,000 years ago, a man died in the region that is now Siberia. The DNA from his remains is now helping researchers understand some of the genetic differences among humans today.

In a paper just published in Nature Communications, SFI Professor Michael Lachmann and colleagues compare that ancient DNA sequence to the variation in genes found in extant human populations.

During the human migration out of Africa, a relatively small number of people left the continent to eventually settle Europe, Asia, and the rest of the world. This small segment of the human population resulted in a genetic bottleneck. Some genetic material present in the overall African population wasn’t represented in the migrating group, while other traits they did carry become much more prominent in the European or Asian populations that later became established.

The ancient Siberian male, whom scientists have named Ust’-Ishim based on the location his bone was found, lived at a critical juncture after the African migration but before traits unique to European, Asian, and other populations began to become established. By comparing DNA from modern populations with the DNA from Ust’-Ishim, scientists can explore when and why certain traits changed in frequency among humans.

Although the results of the paper aren’t particularly shocking—the most functional variations identified were in pigmentation of skin and eye color, and local adaptations such as a mutation for the ability to digest lactose—the new research lays the framework for a process of understanding the roots of genetic variation in humans.

“We don’t have a full sample of the population," says Lachmann. "We just have a single individual. But we used that single individual as a population sample, a sample from the population just after the out-of-Africa bottleneck. We can [compare that to] the frequency of alleles today in different populations since that individual and see how much they changed.”

Read the paper in Nature Communications (March 18, 2016)

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