Recent studies have revealed the reasons for the almost complete absence of Neanderthal genes in the X chromosome of modern humans, despite their presence being recorded in other parts of the genome, reports Hitech.
Although modern Europeans and Asians carry about 1-2% of Neanderthal genes, this indicates that our ancestors interbred with this extinct species.
However, scientists have long been puzzled by one important question: why are there almost no Neanderthal genes in the X chromosome of humans? This region has been dubbed the "Neanderthal desert." The previous hypothesis claimed that natural selection filtered out incompatible genes.
In a new study, researchers proposed an alternative explanation. They analyzed the genomes of Neanderthals that existed after the onset of interbreeding and compared them with the genomes of Homo sapiens.
The results were quite unexpected: Neanderthal X chromosomes contained 62% more human genes compared to other regions of their DNA. This indicates that human genes were passed on to Neanderthals, but not vice versa.
The researchers concluded that the main genetic flows went from Homo sapiens women to Neanderthal men. Women have two X chromosomes, while men have only one, which explains why Neanderthal X chromosomes could not be widely spread in the human population.
Thus, the explanation for the "desert" does not require resorting to the theory of harmful genes. Neanderthal X chromosomes were originally present in small numbers in humans.
The reasons why Neanderthal men chose "wrong" women for reproduction, while Homo sapiens men avoided Neanderthal women, remain a mystery. Scientists have noted this fact, but the detailed reasons for such choices are yet to be determined.
The results of the study were published in the journal Science.
The article "Neanderthal Men Preferred 'Wrong' Women" first appeared on the K-News website.
