How many genetic ancestors do I have

Europeans have three roots

People from all over Europe and the world live in our cities today. But even a good 7,000 years ago, the population of Europe was quite “multicultural”. Because most of today's Europeans even go back to three different groups of Stone Age ancestors, which is proven by genetic analyzes of old and modern DNA. Accordingly, in addition to the genetic heritage of European hunters and gatherers and immigrant farmers, we also carry DNA from Siberian nomad tribes. When these immigrated to Europe and how they mixed with the local populations is still unclear.

Europe has been settled by numerous different cultures and tribes over the years. These included Stone Age hunters and gatherers with Asian roots, but also descendants of the first immigrant representatives of Homo sapiens from Africa and, last but not least, the Neolithic immigrants who brought agriculture with them from the Middle East. How all these populations mixed and to what extent they left their traces in our genetic make-up was only partially clear until now. For example, a 2013 study found that even Europeans living on opposite ends of the continent are relatively closely related - they go back to the same group of ancestors who lived a thousand years ago. In 2012, researchers also found that 5,000 years ago there was still a clear genetic gap between the first farmers in Northern Europe and the hunters and gatherers who also lived there.

An international team of researchers led by David Reich from Harvard Medical School in Boston has now investigated how these fragmentary insights can be put together and what mixture of ancestors today's Europeans can be traced back to. For their study, the researchers first sequenced the genome of nine people who lived in Europe around 7,000 to 8,000 years ago. These included the skeleton of an early farmer discovered in Germany, a representative of an early hunter-gatherer culture unearthed in a rock shelter in Luxembourg and seven 8,000-year-old skeletons of hunters and gatherers found by the Swedes. The researchers compared the results of these DNA analyzes with the genetic make-up of 2,345 people living today from 203 populations within and outside Europe.

Three groups of ancestors instead of just two

The analyzes showed that most Europeans do not go back to just two populations, as previously assumed - hunters and gatherers on the one hand and farmers on the other. Instead, we carry genes from three different prehistoric groups of people. On the one hand, there are early European farmers who go back to ancestors who immigrated from the Middle East. The genetic share of these ancestors is only around 30 percent in the Baltic States and 90 percent in the Mediterranean, as the researchers report. The second group of genes comes from Western European hunters and gatherers who settled in Europe long before the first farmers arrived.

The third population, whose genetic heritage we carry within us, are also hunters and gatherers, but come from Asia. They go back to Paleolithic inhabitants of Siberia, whose genetic heritage can be found today in both Europeans and the inhabitants of the Middle East. Their genes are now represented by up to 20 percent in modern Europeans, as the researchers report. Representatives of this group of people must have come to Europe at some point and mixed with the local hunters and gatherers, but also with the ancestors of the first farmers. However, it is still unclear when this happened.

However, the analyzes also showed that there are exceptions to this three-part origin. The inhabitants of Sicily, Malta and the Ashkenazi Jews can be traced back almost 100 percent to Middle Eastern farmers as ancestors. The Sami, the inhabitants of northwest Russia and the Russian Republic of Mordovia also fall out of the scheme. They are more closely related to Asian populations than to the rest of Europeans. Presumably they go back to a later stream of immigrants from Siberia, as the researchers suspect. Overall, these results underscore the fact that “long-established” Europeans also bear the eventful history of their continent.

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© Wissenschaft.de - Nadja Podbregar
17th September 2014