An international team of researchers examines the genome of an almost complete skull found in Zlat K, Czechia in the early 1950s and now housed in the National Museum in Prague in an article published in Nature Ecology & Evolution. The genome’s segments of Neanderthal DNA were longer than those of the Ust’-Ishim individual from Siberia, the previous oldest modern human sequenced, implying that modern humans existed in Europe more than 45,000 years ago. After modern humans left Africa around 50,000 years ago, ancient DNA from Neandertals and early modern humans revealed that the two groups likely interbred somewhere in the Near East.
As a result, anyone outside of Africa carries about 2% to 3% Neandertal DNA. Those Neandertal DNA segments became progressively shorter in modern human genomes over time, and their length can be used to estimate when a person lived. Furthermore, archaeological evidence published last year suggests that modern humans were already present in southeastern Europe 47-43,000 years ago, but little is known about who these early human colonists were — or their relationships to ancient and modern human groups — due to a scarcity of fairly complete human fossils and the lack of genomic DNA.
An international team of researchers records what is possibly the oldest reconstructed modern human genome to date in a new study published in Nature Ecology & Evolution. The woman known as Zlat (golden horse in Czech) was discovered in Czechia and showed longer stretches of Neanderthal DNA than the 45,000-year-old Ust’ person from Siberia, the world’s oldest modern human genome.
According to the evidence, she was a member of a group that existed before the populations that gave rise to today’s Europeans and Asians broke apart.
According to Viviane Slon, a palaeogeneticist at the University of Tel Aviv in Israel, the study adds to increasing evidence that modern humans mixed with Neanderthals and other extinct relatives on a regular basis. “This occurs at different times and in different ways, and it keeps happening.”
While a recent anthropological analysis focused on the shape of Zlat k’s skull revealed similarities with people who lived in Europe before the Last Glacial Maximum — at least 30,000 years ago — radiocarbon dating yielded sporadic results, some as recent as 15,000 years ago. A clearer image emerged only after Jaroslav Brek of the Prague Faculty of Science and Petr Velemnsk of the Prague National Museum partnered with the genetics laboratories of the Max Planck Institute for the Science of Human History.
“We find signs of cow DNA contamination in the examined bone,” says Cosimo Posth, co-lead author of the report. “This means that a bovine-based adhesive used in the past to consolidate the skull was returning radiocarbon dates younger than the fossil’s true age.” Posth is currently Professor of Archaeo- and Palaeogenetics at the University of Tübingen, where he was previously a research group leader at the Max Planck Institute for the Science of Human History.
The team’s main findings about the age of the fossil, however, were based on Neandertal DNA. Zlat k had about the same amount of Neanderthal DNA in her genome as Ust Ishim or other non-African modern humans, but the segments of Neanderthal ancestry were much longer on average.
According to Kay Prüfer, co-lead author of the report, “the findings of our DNA analysis indicate that Zlat k lived closer in time to the admixture case with Neanderthals.”
Zlat k lived nearly 2,000 years after the last admixture, according to the scientists. The team claims that Zlat k is the oldest human genome known, approximately the same age as — if not a few hundred years older than — Ust’-Ishim, based on their results.
The Oase man’s genome did not reveal whether interbreeding was normal in Europe. He lived at a time when the region’s still sparse Neanderthal population was starting to dwindle.
“It’s fascinating that the first modern humans in Europe didn’t thrive in the end! In the same way that Ust’-Ishim and the so far oldest European skull from Oase 1 display no genetic continuity with modern humans who lived in Europe after 40,000 years ago, Zlat k shows no genetic continuity with modern humans who lived in Europe after 40,000 years ago “According to Johannes Krause, director of the Max Planck Institute for Evolutionary Anthropology and senior author of the report.
The Campanian Ignimbrite volcanic eruption, which occurred about 39,000 years ago and severely affected climate in the northern hemisphere, may have limited the chances of Neanderthals and early modern humans surviving in large parts of Ice Age Europe.
Future genetic studies of other early European individuals will aid in reconstructing the history and decline of the first modern humans to expand out of Africa and into Eurasia before the formation of modern-day non-African populations, as advances in ancient DNA reveal more about our species’ story.
According to a team led by molecular biologist Mateja Hajdinjak and evolutionary geneticist Svante Pääbo, both of the Max Planck Institute for Evolutionary Anthropology (MPI–EVA) in Leipzig, Germany, the three oldest Bacho Kiro individuals, dated to between 45,900 and 42,600 years old, all had recent Neanderthal forebears. Modern non-Africans’ genomes typically contain around 2% Neanderthal ancestry, but the Bacho Kiro individuals had slightly more, at 3.4–3.8 percent, and the chromosome segments — which shorten with each generation — were significantly longer.
Since the oldest individuals from Bacho Kiro and the Zlat k female are not related to later Europeans, ancient or modern, their lineages must have vanished from the area. However, Hajdinjak and her colleagues were surprised to discover that the Bacho Kiro people shared a bond with modern East Asians and Native Americans. According to Hajdinjak, the Bacho Kiro skeletons represent a population that once roamed Eurasia but then disappeared, only to resurface in Asia.
According to Marie Soressi, an archaeologist at the University of Leiden in the Netherlands who plans to study European archaeology through this prism, the fact that some humans from Bacho Kiro had very recent Neanderthal relatives indicates that the groups mixed regularly in Europe.
She believes that stone tools and other artefacts from the Initial Upper Palaeolithic, which differ from Neanderthal and later human toolkits, are the product of cultural exchanges or even mixed populations. “We just want to know what happened, what the historical process was like, and how calm those experiences were.”