New Interactive Map Reveals Human History Of Genetic Mixing

Lawrence LeBlond for redOrbit.com Your Universe Online

A multi-institutional team of researchers this week published in the journal Science a study identifying, dating and characterizing the genetic mixing between populations around the world. Along with the study, the team released an interactive map detailing the histories of this genetic mixing.

Researchers from Max Planck Institute for Evolutionary Anthropology, Oxford University and University College London developed sophisticated statistical methods to analyze the DNA of nearly 1500 people from 95 different populations around the world and from over the past four millennia. These populations hailed from Europe, Africa, Asia and South and Central America.

The groups work was funded by the Wellcome Trust and Royal Society.

DNA really has the power to tell stories and uncover details of humanitys past, said co-senior study author Dr Simon Myers, of Oxford Universitys Department of Statistics and Wellcome Trust Centre for Human Genetics.

Because our approach uses only genetic data, it provides information independent from other sources. Many of our genetic observations match historical events, and we also see evidence of previously unrecorded genetic mixing. For example, the DNA of the Tu people in modern China suggests that in around 1200CE, Europeans similar to modern Greeks mixed with an otherwise Chinese-like population. Plausibly, the source of this European-like DNA might be merchants travelling the nearby Silk Road, explained Dr Myers in a statement.

Dubbed Globetrotter, this powerful technique provides a good in-depth look at the past. For Instance, the method provided invaluable insight into the genetic legacy of the Mongol Empire. Historically, it is believed that the Hazara people of Pakistan are partially descended from Mongol warriors; the study found clear evidence to back up this belief, discovering that Mongol DNA had in fact entered the Pakistani population during the Mongol Empire. As well, six other neighboring populations showed similar evidence of genetic mixing with the Mongols during this period.

What amazes me most is simply how well our technique works, said study lead author Dr Garrett Hellenthal, of the UCL Genetics Institute. Although individual mutations carry only weak signals about where a person is from, by adding information across the whole genome we can reconstruct these mixing events. Sometimes individuals sampled from nearby regions can have surprisingly different sources of mixing.

For example, we identify distinct events happening at different times among groups sampled within Pakistan, with some inheriting DNA from sub-Saharan Africa, perhaps related to the Arab Slave Trade, others from East Asia, and yet another from ancient Europe. Nearly all our populations show mixing events, so they are very common throughout recent history and often involve people migrating over large distances, said Dr Hellenthal.

The team also identified chunks of DNA shared between individuals from different populations, based on the genome data taken from all 1490 individuals. They found that those populations that shared more ancestry also shared more of these chunks. As well, individual chunks gave the team clues about the underlying ancestry along chromosomes.

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New Interactive Map Reveals Human History Of Genetic Mixing