Ancient DNA Provides Clues to Migration, Language and Lactose Tolerance
Advancements in modern DNA technology are providing a deeper and more refined glimpse into ancient populations, revealing timetables for human migrations, the influx of languages, and even the physical attributes of prehistoric populations.
The latest research, published this week in the journal Nature, comes from a team out of the Natural History Museum of Denmark in Copenhagen. Led by Morten Allentoft, a specialist in ancient DNA, the team sequenced the genomes of 101 individuals who lived throughout Eurasia between 3000 BC and AD 700.
This time period has been of considerable interest, mainly because of the radical cultural changes that took place, as people shifted from hunting and gathering to subsistence agriculture. The Bronze Age, which encompasses the period from 3000 BC to 1000 BC in Europe, marked the rise of urban civilization, from Greek, to Roman, to pharaonic Egypt. Thus, it is a prime target for those interested in ancient DNA.
What the sequencing showed was that prior to 3,000 B.C., the genetic makeup of the region resembled those of early farmers from the Middle East, with some evidence pointing to even earlier European hunter/gatherers. But within 1,000 years, the genomes resemble those of the Yamnaya culture, who entered the region in the early Bronze Age and interbred with individuals already living in the region.
This genetic shift had further implications. Allentoft's team speculate that the influx of Yamnaya people may have been partly responsible for the spread of Indo-European languages into Western Europe. But some linguists are not convinced.
"It's pretty clear that these eastern cultures in the Bronze Age are linked to the Yamnaya," says Pontus Skoglund, a population geneticist at Harvard Medical School in Boston, Massachusetts. But he believes the actual origins of all Indo-European languages -- which evolved to include English, French, German, and Hindi -- are far more complicated than the influx of just one group.
Ancient DNA has also revealed some of the physical traits of these early populations. In another study, DNA from 83 ancient Europeans showed mutations linked to thick hair and numerous sweat glands were common among Scandinavians as early as 7,700 years ago. These traits were originally believed to have emerged among East Asians, hinting at potential connections between these two populations. This same research showed people from the Iberian Peninsula became shorter following the shift to agriculture, whereas the Yamnaya, who migrated out of the steppe area, were taller.
Allentoft's research also provided insight into the genes linked to lactose tolerance -- the ability to digest the enzyme lactase, which is believed to have spread as people became more reliant on dairy products. But surprisingly, their research found that the trait was rare among Bronze Age Europeans. Of the 101 individuals sequenced, those making up the Yamnaya group were most likely to have the genes responsible for lactose tolerance, which indicates that these migrants may have been responsible for introducing the trait to Europe.
As DNA technology continues to improve, researchers will gain clearer insight into ancient populations -- where they came from, how they lived and how they adapted to a changing world.
"In another five years, we'll be talking about tens of thousands of ancient genomes" says Greger Larson, an evolutionary geneticist at the University of Oxford, U.K. "It's an interesting time because the technology is moving faster than our ability to ask questions of it. Let's just sequence everything and ask questions later."
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