Neanderthals arrived in Europe almost 300 thousand years earlier than the first Cro-Magnons, which gave them more time to adapt to environmental conditions that were very different from African ones.
One of the main adaptations was the change in circadian rhythms , which came in line with the seasonality of the climate and the accompanying changes in the length of daylight hours.
However, the direct ancestors of modern man did not have so much time for gradual adaptation: the first Homo sapiens left Africa about 100 thousand years ago, starting to spread throughout Eurasia.
And about 25 thousand years ago, people already penetrated the Arctic, crossed the Bering Strait (which at that time was an isthmus) and ended up in North America.
So instead of relying on natural selection, our ancestors acted differently: they “borrowed” the necessary genes from the Neanderthals.
This is the conclusion reached by a group of scientists from several research centers in the United States, who analyzed 28 genes that affect the circadian rhythm.
According to a study 12 of these genes (such as CLOCK, PER2, RORB and RORC) are present in the Neanderthal genome.
So at least some of them could have been passed on to our ancestors from their European relatives, with whom the Cro-Magnons interbred many times.
Such “borrowings” of useful genes in nature are not at all uncommon: for example, the jaguar was found to have genes inherited from a lion and allowed this South American predator to see better, and interspecific hybridization of African cichlids and Galapagos finches has repeatedly led to the emergence of new species.
In other words, the crossing of our ancestors with Neanderthals not only increased the risk of developing vascular diseases and intestinal inflammation in some modern people, but also allowed them to adapt extremely quickly to the changing climatic conditions of Eurasia.
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