Unlocking the Past: When Homo Sapiens and Neanderthals Interbred
Although Neanderthals died extinct some 39,000 years ago, these near relatives of our species are still around in some ways. Because Neanderthals and Homo sapiens interbred, their legacy is still present in the genes of the majority of individuals on Earth. In addition to demonstrating how Neanderthal elements have influenced human genes in areas like metabolism, immunological response, and skin color, new research offers the most accurate estimate to date of when this mixing took place, with the interaction peaking approximately 47,000 years ago.
Based on bones discovered in a cave in the German town of Ranis, a team of researchers analyzed the genomes of three female and three male Homo sapiens individuals who lived approximately 45,000 years ago. They also looked at the genome of a woman from the same era whose skull was discovered in a cave at Zlaty Kun Mountain in the Czech Republic. The oldest Homo sapiens DNA ever sequenced was used in the study, which was published in the journal Nature. It provided a date range for the mixing of roughly 49,000 to 45,000 years ago.
The genomes of 300 modern and prehistoric Homo sapiens, including 59 who lived between 2,000 and 45,000 years ago, were analyzed by a second team of researchers. According to the findings, which was published in the journal Science, the mixing occurred between around 50,500 and 43,500 years ago.
The interbreeding, which was discovered to have occurred more recently than previously thought, was characterized by the scientists as a single, prolonged phase of gene flow that lasted for many generations. Beyond assuming that Homo sapiens and Neanderthals interbred and produced offspring together, it is challenging to determine the exact nature of their interactions based on genomic data. Although the researchers were unable to identify the exact location of this interbreeding, they believed it most likely occurred in the Middle East.
Formally known as Homo neanderthalensis, Neanderthals were larger-browed and more powerfully built than modern humans. They existed from about 430,000 years ago until they vanished not long after Homo sapiens, a species that originated in Africa some 300,000 years ago, migrated into regions that the Neanderthals had occupied in the Middle East, Europe, and Asia. Neanderthals were clever, according to earlier studies, and they produced art and used sophisticated group-hunting techniques, pigments for body painting, symbolic artifacts, and possibly spoken language. Neanderthal genes make up about 1% to 2% of the DNA of most modern humans.
Before modern humans arrived, Neanderthals lived for thousands of years outside of Africa, where they were likely acclimated to the temperature and diseases. As a result, some of their genes might have benefited modern humans, according to Priya Moorjani, a population geneticist at the University of California, Berkeley, who led the study.
One Neanderthal-inherited immunity gene variation, for example, offers protection against coronaviruses such as the one that sparked the COVID epidemic. Over time, the frequency of certain Neanderthal genes related to skin pigmentation and the immune system in modern humans increased, indicating their importance for survival. However, according to Moorjani, "certain genetic areas are nearly devoid of Neanderthal heritage." This suggests that certain Neanderthal gene variations were not inherited by subsequent generations and proved fatal to modern humans.
A mother and daughter were identified among the Ranis. It was discovered that two of the Ranis were distantly related to the Zlaty Kun woman, who lived some 145 miles (230 km) away. Their physical appearance was revealed by the genomes. According to Geoff Smith, a zooarchaeologist at the University of Reading in England, one of the researchers, "these early Europeans numbered just a few hundred and had dark skin, dark hair, and brown eyes, reflecting their arrival from Africa."
These early European Homo sapiens pioneers had to contend with the hard environment of the Ice Age. A lost branch of the human family tree, the genetic data from the Ranis and Zlaty Kun people revealed that they had no living offspring today, indicating that their population had died out. The remnants of Zlaty Kun depict a dangerous environment.
According to evolutionary biologist Arev Sümer of the Max-Planck-Institute for Evolutionary Anthropology in Germany, one of the research leaders, "marks on the skull suggest towards predators, possibly hyenas, to have either attacked her or gnawed on the skull after her death." There has been much discussion on what happened to the Neanderthals. Divergent opinions exist on the part that modern humans played in Neanderthal extinction. We consider it at least possible that a significant portion of the probably even smaller Neanderthal population that was present in the area at the time may have been assimilated by the comparatively small entering modern human population. Given that their DNA is still present in the genomes of modern humans, they are more successful than ever and, in a sense, still alive," Sümer stated.
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