Neanderthal ancestry identifies oldest modern human genome

In an article published in Nature’s ecology and evolution, an international team of researchers is analyzing the genome of an almost complete skull first discovered in Zlatý Kůň, Czechia in the early 1950s and now housed in the National Museum in Prague. The Neanderthal DNA segments in its genome were longer than those of the Siberian individual Ust’-Ishim, the oldest modern human sequenced, suggesting that modern humans lived in the heart of Europe more than 45,000 years old.

Ancient DNA from Neanderthals and early modern humans has recently shown that the groups likely crossed paths somewhere in the Near East after modern humans left Africa around 50,000 years ago. As a result, all people outside of Africa carry around 2% to 3% of Neanderthal DNA. In modern human genomes, these segments of Neanderthal DNA have grown shorter and shorter over time, and their length can be used to estimate when an individual has lived. Archaeological data released last year further suggests that modern humans were already present in southeastern Europe 47-43,000 years ago, but due to the paucity of fairly complete human fossils and the lack of In genomic DNA, little is known about who these early human settlers were. – or their relations with ancient and current human groups.

In a new study published in Nature’s ecology and evolution, an international team of researchers reports what is probably the oldest modern human genome reconstructed to date. First discovered in Czechia, the woman known to researchers as Zlatý kůň (golden horse in Czech) displayed segments of Neanderthal DNA longer than the 45,000-year-old Ust’-Ishim individual from Siberia , the oldest modern human genome to date. Analysis suggests that she was part of a population that formed before the populations that gave birth to today’s Europeans and Asians split up.

A recent anthropological study based on the shape of Zlatý kůň’s skull has shown similarities to people who lived in Europe before the Last Ice Maximum – at least 30,000 years ago – but radiocarbon dating has produced sporadic results, some as recent as 15,000 years ago. It was only when Jaroslav Brůžek from the Faculty of Science in Prague and Petr Velemínský from the National Museum in Prague collaborated with the genetics laboratories of the Max Planck Institute for the Science of Human History that a clearer picture appeared.

“We found evidence of contamination of cow DNA in the bone analyzed, suggesting that a bovine-based glue used in the past to consolidate the skull returned radiocarbon dates younger than age. real fossil, says Cosimo Posth, co-lead author of the study. Posth was previously a research group leader at the Max Planck Institute for the Science of Human History and is currently Professor of Archeology and Paleogenetics at the University of Tübingen.

However, it was Neanderthal DNA that led the team to their main conclusions about the age of the fossil. Zlatý kůň carried roughly the same amount of Neanderthal DNA in his genome, as Ust Ishim or other modern humans outside of Africa, but the segments of Neanderthal ancestry were on average much longer.

“The results of our DNA analysis show that Zlatý kůň lived closer in time to the Neanderthal mixing event,” says Kay Prüfer, co-lead author of the study.

Scientists have been able to estimate that Zlatý kůň lived about 2000 years after the last mixing. Based on these results, the team argues that Zlatý kůň represents the oldest human genome to date, roughly the same age as – if not a few hundred years older than – Ust’-Ishim.

“It is quite fascinating that the first modern humans in Europe were ultimately unsuccessful! Just as with Ust’-Ishim and the oldest European skull in Oase 1, Zlatý kůň shows no genetic continuity with modern humans who lived in Europe after 40,000 years ago, ”says Johannes Krause, lead author of the study and director of the Max Planck Institute for Evolutionary Anthropology.

One possible explanation for the discontinuity is the Campanian ignimbrite volcanic eruption around 39,000 years ago, which severely affected the climate in the northern hemisphere and may have reduced the chances of survival of Neanderthals and early modern humans in large parts of the Ice Age in Europe.

As advances in ancient DNA reveal more about the history of our species, future genetic studies of other early European individuals will help reconstruct the history and decline of the first modern humans to expand out of it. Africa and Eurasia before the formation of the modern era. non-African populations.

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