The oldest modern human genome ever discovered in a skull

The oldest modern human genome ever discovered in a skull

A genome sequenced from a "modern" human skull has been dated as being older than 45,000 years, making it the oldest discovery of its kind. It is a significant archaeological discovery, but the use of an unconventional dating method leaves doubts about the absolute certainty of the result. In a related study, scientists have also shown that mixing between Neanderthals and humans would have occurred much more often than is believed.

A Neanderthals

Modern humans , otherwise known as Homo Sapiens, developed around 300,000 years ago in Africa. There are skeletal remains of these distant ancestors of ours, but the fossil record is scarce. Even poorer is the genetic evidence, the oldest of which is the genome of a Ust'-Ishim person who lived 45,000 years ago in Western Siberia, described in 2014.

According to recent research published in Nature Ecology & Evolution, however, scientists may have stumbled upon 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 may be the oldest modern human genome reconstructed from a fossil record. If the dating method used is found to be reliable, the genome, extracted from a skull found in the Czech Republic, could be at least 45,000 years old, but perhaps we would be looking at something even older.

A related document, Also published in Nature Ecology & Evolution, it describes the remains of the first modern humans found in a Bulgarian cave. Dating from around the same time, the DNA of these people suggests that crossing with Neanderthals was a widespread practice.

The skull described in the Prüfer document was extracted from the Koněprusy cave in 1950 and was found along with other skeletal remains. This cave is located in the locality of Zlatý kůň, which means "golden horse" in Czech, just 40 km from Prague.

Genetic analysis of the skull, which belonged to an adult female, reveals between 2% and 3% Neanderthal ancestry, a percentage that basically corresponds to the quantities found in non-African people today. However, it must be said that no current human being descends directly from the woman of Zlatý kůň, since she belonged to a population that did not transmit any DNA to subsequent European or Asian populations.

Prüfer then explained that as far as we know, the population to which the woman belonged did not contribute to the birth of today's ones. He then went on to hypothesize that his people became extinct along with the Neanderthals, who lived in Europe at the time, and that a large volcanic eruption in Italy that occurred around 39,000 years ago may have contributed to their demise.

La Initial radiocarbon dating of the skull suggested that the find was about 15,000 years old. Not believing the result to be reliable (the anatomy of the skull suggested an earlier dating), Prüfer and his colleagues tried again, obtaining an origin of the skull close to 27,000 years ago. After some cleansing treatments, a third radiocarbon date has been determined, suggesting that the woman lived about 19,000 years ago. It was at this point that the scientists realized they were dealing with highly contaminated specimens. Evidence of cow DNA contamination was found in the bone analyzed, suggesting that a bovine-based glue may have been used in the past to repair the find, thus returning a more recent dating than the true age of the fossil.

With radiocarbon dating excluded as a useful tool for analyzing this sample, the team turned to is aimed at a technique in which the length of the DNA segments can be used to infer the antiquity of the specimen. In particular, the scientists measured the length of Neanderthal segments, as these segments shorten with each generation.

This analysis suggests that the woman from Zlatý kůň lived at least 2,000 years after the last possible cross between its human ancestors and Neanderthals, which is an approximate time between 63 and 78 generations. The Neanderthal segments were longer than those observed in the modern human genome of the Ust'-Ishim individual, suggesting that the woman from Zlatý kůň was one of the first inhabitants of the area, following migrations out of Africa. , older than the Ust'-Ishim find, separated from the Neanderthals "only" by a number of generations oscillating between 84 and 94.

To learn more about our ancestors and the evolutionary processes that led up to us, we recommend The Great Tale of Human Evolution written by Giorgio Manzi (Amazon link).

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