A genome composed of a modern human skull is about 45,000 years old, making it the oldest discovery of its kind. This is an important archaeological discovery, but the use of an unconventional dating method leaves the result in doubt. In a related study, scientists also show that mixing between Neanderthals and humans happened more often than we thought.
Modern people, also known as Homo sapiens, emerged about 300,000 years ago in Africa. There are skeletal remains of our ancestors in the distance, but the fossil record is weak. Worse still is the genetic evidence, the oldest of which is the genome of a 45,000-year-old Ust’-Ishim person from Western Siberia, describe in 2014.
But like new research published today in Nature Ecology & Evolution revealed, scientists may have come across an even older genome. A team with Kay Prüfer of the Max Planck Institute for the History of Human History in Germany discovered the very oldest reconstructed modern human genome in the fossil record. That is, if the dating method used can be considered reliable. The genome, drawn from a skull found in the Czech Republic, appears to be at least 45,000 years old and possibly even older.
A related paper, also today in Nature Ecology & Evolution, describes the remains of early modern humans found in a Bulgarian cave. The DNA of these people dates from about the same period, suggesting that interbreeding with Neanderthals was probably more common than previously thought.
The skull described in the Prüfer article was pulled from the Koněprusy cave in 1950 and found next to other skeletal remains. This cave is located in Zlatý kůň, which in Czech means ‘golden horse’, and it is a short drive of 40 km from Prague.
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Genetic analysis of the mostly intact skull, which belonged to a female woman, shows that she had between 2% and 3% Neanderthal descent, which basically corresponds to the amounts found in people not living in Africa today. That said, no people living today are directly descended from the Zlatý kůň woman, as she was part of a population that passed on no DNA to the subsequent European or Asian population of early modern humans.
“As far as we can determine, the population to which she belongs has not contributed to the current population,” Prüfer explained in an email. “We speculate that her people, along with Neanderthals, who lived in Europe at the time, became extinct and that a major volcanic eruption in Italy that occurred about 39,000 years ago may have contributed to their downfall.”
Prüfer refers to the Campanian Ignimbrite volcanic eruption, which severely disrupted the climate in the northern hemisphere, and made life difficult for both modern humans and Neanderthals during the last European ice age.
This is all well and good (quite) controversial – when it comes to dating the skull, there are problems.
The initial radiocarbon dating of the skull yielded a date almost 15,000 years ago. Because she does not believe this to be true (the anatomy of the skull suggested an older date), Prüfer and her colleagues tried again, resulting in a date closer to 27,000 years ago. After some cleaning treatments, a third radiocarbon date was determined, indicating that the woman lived about 19,000 years ago. At this point, the scientists realized that they were dealing with highly infected specimens.
‘We found evidence of contamination of cow DNA in the analyzed bone, suggesting that an adhesive based on cattle was used earlier to [fix] the skull was making radiocarbon dates younger than the fossil’s true age, ”Cosimo Posth, co-lead author of the study and a professor of paleogenetics at the University of Tübingen, explained in a statement. Posth previously worked as a research group leader at the Max Planck Institute.
Since radiocarbon dating has been ruled out as a useful tool for this sample, the team has resorted to a technique in which the length of DNA segments can be used to deduce a person’s age. The scientists specifically measured the length of the Neanderthal segments, as these segments become shorter with each successive generation.
This analysis suggests that the Zlatý kůň woman lived at least 2000 years after the last crucifixion event involving her modern human and Neanderthal ancestors (approximately 63 to 78 generations). The “lengths of the Neanderthal segments are longer than those observed in the currently oldest modern human genome of the ~ 45,000-year-old Ust’-Ishim individual from Siberia, suggesting that this individual from Zlatý kůň one of the earliest Eurasian inhabitants is what follows the expansion from Africa, ”the authors write in their study. According to the newspaper, the person Ust’-Ishim was separated from Neanderthals by 84 to 94 generations.
The new results work under the assumption of a single breeding event and mean that Zlatý kůň is basically the same age as the approximately 45,000-year-old Ust’-Ishim monster, or possibly ‘up to a few hundred years older’, according to the paper. But if a second Neanderthal crucifixion event occurred along the Ust’-Ishim lineage to this common Neanderthal mixture, then “Zlatý kůň may even be thousands of years older than Ust’-Ishim,” the authors wrote, adding that they not yet found support for a second Neanderthal blend.
This is all very interesting, but obviously a firmer date should be set, hopefully through the use of other methods.
The authors “really do not know how old the skull is and the extent is large,” Israel Hershkovitz, an archaeologist at Tel Aviv University and an expert on modern humans, said in an email. Hershkovitz said the data used to determine the age of the skull – mitochondrial DNA and the pattern of the Neanderthal gene segments – were ‘interesting’, but he was not entirely sure about its effectiveness as a dating technique. .
However, if these results are accurate, the Zlatý kůň specimen now represents the oldest modern human genome in the fossil record. What’s more, the new article offers a rare glimpse into the genetic makeup of early modern European people dating from this period.
The group to which the woman Zlatý kůň belonged did not survive, which is also interesting. This indicates several waves of migrations to Europe from Africa, and / or some complex scenarios for population replacement, in which some groups survive and others do not. That this sample belongs to “a population before the division between European and Asian populations” is significant, Hershkovitz said, provided their first assertion, “that the skull is very old, is correct.”
That modern people lived in Europe so long ago is not an important piece. Evidence from 2020 indicates that modern humans were is present in southeastern Europe between 47,000 and 43,000 years ago, while evidence from 2019 suggests that some modern humans had it reached it Europe, specifically Greece, as long as 210,000 years ago.
The second paper, led by Mateja Hajdinjak of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, describes the remains of early modern humans found in the Bacho Kiro Cave in Bulgaria. This surplus was initially described in the above article from 2020, but the new analysis dives into their DNA.
Neanderthals and humans came into being at some point between 55,000 and 60,000 years ago. Until now, however, archaeologists have had only one person, a 40,000-year-old Oasis1 fossil from Romania, which exhibited recent Neanderthal descent, in a finding that modern humans and Neanderthals were bred on several occasions.
“However, we could not rule out that it was just a coincidence,” Hajdinjak explained in an email. “Now in this study, we have all three individuals of about 45,000 years old from the Bacho Kiro Cave with Neanderthal ancestors very close in their family history, just like Oasis1,” she said, meaning that the “mixing was more common than what we thought before. ”
The oldest three individuals found in Bacho Kiro did indeed have between 3% and 3.8% Neanderthal DNA, which is slightly more than the current population. It’s amazing that these people had Neanderthal ancestors, as few as six – or even fewer – generations back, which is truly amazing.
“Contrary to what might be expected of ancient individuals in Europe, Bacho Kiro individuals are more closely related to human groups who contributed their genetic material to East Asians rather than Western Eurasians,” Hajdinjak said. “It is important that all older individuals of the Bacho Kiro Cave have Neanderthal ancestors very closely in their pedigrees, indicating that the mixing between these first people in Europe and Neanderthals was common.”
Paleogenetics reveals some remarkable things about our past, especially as it works in conjunction with both skeletal and archaeological artifacts. Our history is increasingly coming into focus, and the view is only becoming more intriguing.