Ancient DNA analysis: European origins debated – Sciences et Avenir

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Montagnes du Caucase

More than 10,000 years ago, the origin of European populations took place on the borders of Asia. If for two centuries the scientific debate has rather located these roots in the Eurasian steppes, a new work published in Science places them a little further south, towards the Caucasus. By analyzing the ancient DNA of more than 700 individuals, these new results tell a whole new story of the old continent… Which is not unanimous. “DNA doesn’t lie, but it doesn’t tell the story either,” says American anthropologist Benjamin Arbuckle, co-author of a perspective article on the new work in Science. he chooses the stories to tell,” he adds to Sciences. et Avenir. And according to him, these stories serve to interpret the analyzes of ancient genomes “inevitably project specific visions of the world.” The crux of the debate lies, above all, in the interpretation they make the authors of the DNA traces of the Iamnaeans, this nomadic tribe that occupied the Pontic steppes (the plains that cross Ukraine, Russia and Kazakhstan) 3,000 years ago, are found in almost all the peoples studied. These peoples are the ones who bordering the Black Sea: the Iamnaeans in the north, the Armenians in the north, in the east (under the Caucasus Mountains), the Anatolians in the south in present-day Turkey, and in the west the Balkans, the Romans and the Greeks. According to research However, westward and northward migrations from the western Asian highlands (Caucasus, above Armenia) split an original “Proto-Indo-Anatolian” language into Anatolian (in Anatolia) and Indo-European (in Balkans and Greece through d the Yamnayas). ). Click to view larger image. Credits: Science/Lazaridis The mystery of the Anatolians, who inherited a language but not the DNA Iosif Lazaridis, a geneticist at Harvard (USA), is the first author of the three new studies published in Science. “We already knew that the Yamnayas played a very important role in the spread of Indo-European languages”, explains this family that is the mother of multiple European and Asian languages ​​such as Sanskrit (India), Greek and Latin. And sure enough, DNA analyzes of 777 individuals who lived between the Neolithic period (12,000 years ago) and the Medieval period (1,000 years ago) around the Black Sea confirm a strong presence of Yamnaya DNA… Except in Anatolia! However, the languages ​​formerly spoken in this region, such as Hittite, are part of the Indo-European languages ​​and should therefore have been spread by the Yamnayas. Could this diffusion have taken place without leaving a trace in local DNA? An original Indo-European spoken in the Caucasus, a divisive theory More than 10,000 years ago, the origin of European populations played out at the edges of Asia. If for two centuries the scientific debate has rather located these roots in the Eurasian steppes, a new work published in Science places them a little further south, towards the Caucasus. By analyzing the ancient DNA of more than 700 individuals, these new results shed unprecedented and precious light on the origins of the old continent. But the interpretation of these results inspires a whole new history of Europe… Which is not unanimous. “DNA doesn’t lie, but it doesn’t tell the story either,” says American anthropologist Benjamin Arbuckle, co-author of a perspective article on the new work in Science. he chooses the stories to tell,” he adds to Sciences. et Avenir. And according to him, these stories serve to interpret the analyzes of ancient genomes “inevitably project specific visions of the world.” The crux of the debate lies, above all, in the interpretation they make the authors of the DNA traces of the Iamnaeans, this nomadic tribe that occupied the Pontic steppes (the plains that cross Ukraine, Russia and Kazakhstan) 3,000 years ago, are found in almost all the peoples studied. These peoples are the ones who bordering the Black Sea: the Iamnaeans in the north, the Armenians in the north, in the east (under the Caucasus Mountains), the Anatolians in the south in present-day Turkey, and in the west the Balkans, the Romans and the Greeks. According to research However, westward and northward migrations from the western Asian highlands (Caucasus, above Armenia) split an original “Proto-Indo-Anatolian” language into Anatolian (in Anatolia) and Indo-European (in Balkans and Greece through d the Yamnayas). ). Click to view larger image. Credits: Science/Lazaridis The mystery of the Anatolians, who inherited a language but not the DNA Iosif Lazaridis, a geneticist at Harvard (USA), is the first author of the three new studies published in Science. “We already knew that the Yamnayas played a very important role in the spread of Indo-European languages”, explains this family that is the mother of multiple European and Asian languages ​​such as Sanskrit (India), Greek and Latin. And sure enough, DNA analyzes of 777 individuals who lived between the Neolithic period (12,000 years ago) and the Medieval period (1,000 years ago) around the Black Sea confirm a strong presence of Yamnaya DNA… Except in Anatolia! However, the languages ​​formerly spoken in this region, such as Hittite, are part of the Indo-European languages ​​and should therefore have been spread by the Yamnayas. Could this diffusion have taken place without leaving a trace in local DNA? An original Indo-European spoken in the Caucasus, a divisive theory For Iosif Lazaridis, the Yamnayas probably played a “trigger” role, often indirectly. “Our work shows that Armenia is one of the few places in the world to have obtained its Indo-European languages ​​’directly’ from the Yamnayas around 3000 BC. This is probably also true for Balkan populations such as Greeks and Greek Albanians. .” The unexpected absence of steppe DNA in Anatolia despite the use of a language related to theirs could be explained in two ways, according to the researcher: “Either the steppe migrants were not going to Anatolia at all, or they were very few in number and were absorbed by the local population.” For him and the rest of the team, it is possible that the Yamnayas are not the source of the Indo-European languages, but merely an emanation of ‘an even older original language, from which Anatolian languages ​​would also derive. the people using this original language would be in the Caucasus, mountains separating the Yamnayas from the Anatolians, and whose DNA is found in both peoples A beautiful story that, however, does not convince everyone In Science News, linguist Guus Kroonen explains that it is known that the people of the Caucasus must have been familiar with agriculture at the time, but the oldest versions of Indo-European contain only one word for cereals and no word for legumes or plow So the speakers of this language “were not very familiar with agriculture”, unlike the Caucasians. “The linguistic evidence and the genetic evidence do not seem to match,” he concludes. But Iosif Lazaridis does not dismount until now. “If our theory is correct, then the common ancestor of the Yanamna and Anatolian peoples is hidden somewhere in the highlands between Turkey, Armenia and the Caucasus. (…) We must find it!” Mainly male DNA data For his part, Benjamin Arbuckle points to a story based on excessive over-interpretation of raw genetic data.First, he questions the method, which only looked at people’s ancestry by looking at the Y chromosome, which it only allows for detection of male lines, transmission from father to son.” The main problem with these articles is that they use data about male lines to talk about the big events of European prehistory, which gives the impression that men are the only characters of history,” raises the researcher. Iosif Lazaridis protests. “We evaluated mitochondrial DNA (transmitted by the mother, editor’s note) in all our samples. However, it is less differentiated between human populations and less informative about their relationships and migration patterns” than the Y chromosome, justifies-. “Its use would require much larger sample sizes to discern, more subtle, differences between populations”. Although methodologically justifiable, focusing on the Y chromosome could mask the interbreeding of populations due to the movement of women, the unions between members of different peoples or even the sex trafficking or sexual violence that may accompany the conflicts, for example? This is the problem posed by Benjamin Arbuckle. But Iosif Lazaridis retorts: “Ancient DNA cannot tell us everything. Except in circumstances linked to a very specific archaeological context, knowledge of a person’s genome tells us nothing about the individual context: whether the action was done voluntarily, under duress or by violence. I think we have to be humble as geneticists and not exaggerate what the genome can tell us about past societies.” The two scientists agree on one point. To dig deeper into these results, “it will be necessary to dig deeper into the mitochondrial lineages and analyze autosomal DNA (from non-sex chromosomes, neither X nor Y, ed.) on a more local scale to try to understand the social mechanisms underlying “shared ancestry.” A window into peoples of unknown origin, in Cyprus and Urartu If the interpretation of the origins of Indo-European is debated based on these results, other aspects of this work raise a more consensual interest. Thus, some DNA samples were surprising among the 777 remains studied. They refer to individuals from the ancient Iron Age kingdom of Bianili (800 BC to AD), also called Urartu by neighboring countries and straddling eastern Turkey and present-day Armenia. “DNA analyzes reveal two groups there, one (in Turkey) without steppe ancestry ria and the other (in Armenia) with steppe ancestry,” observes Iosif Lazaridis with surprise. In the same kingdom, the Anatolian strip was therefore devoid of Yanamna DNA, unlike the Armenian part. “I think this is a remarkable match with the known languages ​​spoken in the region, the Urartian (non-Indo-European) and Armenian (Indo-European) languages. Another interesting find, according to Benjamin Arbuckle, comes from DNA unearthed from Neolithic Cypriots .” Their data show that Cyprus was populated by early farmers (10,000 years ago), whose genomes are a mix of Anatolian farmers and Levantine foragers, which is consistent with archaeological evidence of links with Anatolia”. Do not underestimate the archaeological data against the DNA data An important match, since the archaeological evidence should not be considered “speculative” against the “slightly overestimated” DNA data which would give the “answer real,” explains Benjamin Arbuckle. Still, this DNA data “offers a revolutionary new way of exploring the past,” a new approach that the researcher considers “legitimately exciting.” “Some interpret actions are currently a little clumsy and crude, but as data becomes available and resolution increases, we will continue to make discoveries about the history of people and places we know nothing about. The impact of these discoveries could be particularly significant in regions of the world without written records or long archaeological traditions”, such as the Amazon or New Guinea.
#Ancient #DNA #analysis #European #origins #debated #Sciences #Avenir

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