A genome sequenced from a modern human skull was dated to about 45,000 years ago, making it the oldest such discovery. It is a significant archaeological discovery, but the use of an unconventional method of dating leaves the result in doubt. In a related study, scientists also show that the mix between Neanderthals and humans happened more often than we thought.
Modern people, otherwise known as homo sapiens, it appeared about 300,000 years ago in Africa. There are skeletal remains of our distant ancestors, but fossil records are poor. Even weaker is the genetic evidence, the oldest of which is the genome of a 45,000-year-old Ust’-Ishim from western Siberia. described in 2014.
But just as new research published today in Nature Ecology & Evolution reveals, scientists may have come across an even older genome. A team led by Kay Prüfer of the Max Planck Institute for the Science of Human History in Germany has discovered what could very well be the oldest modern human genome reconstructed from fossil records. That is, whether the meeting method used can be considered reliable. The genome, extracted from a skull found in the Czech Republic, appears to be at least 45,000 years old and possibly even older.
A connection paperalso today in Nature Ecology & Evolution, describes the remains of the first modern humans found in a Bulgarian cave. Dating around the same time period, the DNA of these people suggests that crossing with Neanderthals was probably more common than previously thought.
The skull described in the Prüfer newspaper was removed from the Koněprusy cave in 1950 and was found along with other skeletal remains. This cave is located in Zlatý kůň, which means “golden horse” in Czech and is located 40 kilometers from Prague.
G / O Media may receive a commission
Genetic analysis of the mostly intact skull, which belonged to a human female, shows that she had between 2% and 3% Neanderthal ancestors, which is practically in line with the amounts found in non-African people living today. That being said, no man living today is a direct descendant of the woman Zlatý kůň, because he belonged to a population that did not transmit DNA to later European or Asian populations of early modern humans.
“As far as we can tell, the population he belonged to did not contribute to the current populations,” Prüfer explained in an e-mail. “We speculate that its people disappeared along with the Neanderthals, who lived in Europe at the time, and that a large volcanic eruption in Italy, which occurred about 39,000 years ago, could have contributed to their extinction.”
Prüfer refers to Campanian igneous volcanic eruption, which severely disrupted the climate in the northern hemisphere, making life difficult for both modern humans and Neanderthals in the last European ice age.
All of these are good and (reasonably) undisputed – problems arise when it comes to dating the skull.
The original radiocarbon dating of the skull gave a date close to 15,000 years ago. Without believing this to be true (the anatomy of the skull suggested an older encounter), Prüfer and her colleagues tried again, resulting in a meeting closer to 27,000 years ago. Following cleansing treatments, a third time was established with radiocarbon, which suggests that the woman lived about 19,000 years ago. At this point, the scientists realized that they were dealing with a highly contaminated specimen.
“We found evidence of cow DNA contamination in the analyzed bone, suggesting that a cattle-based adhesive used in the past for [fix] the skull returned radiocarbon data younger than the true age of the fossil, “Cosimo Posth, co-author of the study and professor of paleogenetics at the University of Tübingen, said in a statement. Posth previously worked as a research group leader at the Max Planck Institute. .
With radiocarbon dating excluded as a useful tool for this specimen, the team resorted to a technique in which the length of DNA segments can be used to deduce a person’s age. Specifically, scientists have measured the length of Neanderthal segments, as these segments become shorter with each successive generation.
This analysis suggests that the woman Zlatý kůň lived at least 2,000 years after the last crossover event involving her modern human and Neanderthal ancestors (about 63 to 78 generations). “The lengths of Neanderthal segments are longer than those observed in the oldest modern human genome of the Ust’-Ishim individual, 45,000 years old, from Siberia, suggesting that this individual from Zlatý kůň is one of the first Eurasian inhabitants to expand. outside Africa “, the authors wrote in their study. The Ust’-Ishim person has been separated from Neanderthals for about 84 to 94 generations, according to the newspaper.
Working under the assumption of a single crossing event, the new results mean that Zlatý kůň is practically the same age as the Ust’-Ishim specimen of about 45,000 years, or possibly “a few hundred years older”, according to the paper. But if a second Neanderthal crossing event occurred along the Ust’-Ishim line after this common Neanderthal mix, then “Zlatý kůň could be even a few thousand years older than Ust’-Ishim,” they wrote. the authors, adding that he found no support for a second Neanderthal mixture.
All of this is very interesting, but it needs to be set more firmly, hopefully by using other methods.
The authors “really don’t know how old the skull is and the range offered is wide,” said Israel Hershkovitz, an archaeologist at Tel Aviv University and an expert on early modern people, in an email. That being said, Hershkovitz said the data used to determine the age of the skull – mitochondrial DNA and the model of Neanderthal gene segments – is “interesting”, but is not entirely sure about its effectiveness as a dating technique.
However, if these results are accurate, the Zlatý kůň specimen is now the oldest modern human genome in fossil records. Moreover, the new paper provides a brief look at the genetic structure of the first modern Europeans of this time period.
The group to which the woman Zlatý kůň belonged did not survive, which is also interesting. It suggests multiple waves of migration to Europe from Africa and / or some complex population replacement scenarios, in which some groups survived and others did not. That this specimen belonged to “a population prior to the division between European and Asian populations” is significant, Hershkovitz said, provided their first statement, “that the skull is very old, is correct.”
That modern people lived in Europe a long time ago is not a major stretch. Evidence from 2020 suggests that modern humans were present in southeastern Europe between 47,000 and 43,000 years ago, while evidence from 2019 suggests that some modern humans had reached Europe, especially Greece, 210,000 years ago.
The second work, led by Mateja Hajdinjak of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, describes the remains of the first modern humans found in the Bacho Kiro Cave in Bulgaria. These remnants were originally described in the above-mentioned paper from 2020, but the new analysis is thrown into their DNA.
Neanderthals and humans crossed paths between 55,000 and 60,000 years ago. However, until now archaeologists had only one person, a Oase1, 40,000 years old, from Romania, who exhibited recent Neanderthal ancestors, in a finding that suggests modern humans and Neanderthals raised several times.
“However, we could not rule out that this was just a coincidence,” Hajdinjak said in an email. “Now, in this study, we have all three individuals of about 45,000 years old in Bacho Kiro Cave with very close Neanderthal ancestors in their family history, just like Oase1,” she said, which means that “mixing was more common. than what we previously thought. ”
Indeed, the three oldest individuals found in Bacho Kiro carried between 3% and 3.8% Neanderthal DNA, which is slightly more than current populations. Incredibly, these people had Neanderthal ancestors just six – or even fewer – generations ago, in what is a truly amazing discovery.
“Contrary to what might be expected of ancient European individuals, Bacho Kiro individuals are more closely related to the human groups that contributed their genetic material to East Asians rather than Eurasians,” Hajdinjak said. “Crucially, all the individuals in the older Bacho Kiro Cave have very close Neanderthal ancestors in their family trees, which suggests that the mixture of these early Europeans and Neanderthals was common.”
Paleogenetics reveals some remarkable things about our past, especially when they work together with skeletal and archaeological artifacts. Our history is becoming more and more focused, and the vision is becoming more and more interesting.