Another Neanderthal footprint
Unknown "pieces" of Neanderthals were found in humans
Scientists at the University of California at Davis have found new parts of the genome of Neanderthals and other ancient people in the DNA of modern humans. This is reported in a press release on the UC Davis website: Dark Centers of Chromosomes Reveal Ancient DNA.
Ancient DNA is located in the centromere – the central part of the chromosome that connects its two parts (chromatids). When the mother cell divides, both chromatids, each of which has the same set of genes, diverge in different directions, getting into daughter cells. The DNA of the centromere mainly consists of repeating sequences, which makes it difficult to create an accurate genetic map of this site.
Since the centromere does not participate in crossing–over, the process of exchanging sites between homologous chromosomes, there are ideal conditions for the existence of ancient genetic sequences that do not undergo changes. This, in turn, allows us to identify haplotypes – aggregates of immutable DNA inherited from distant ancestors. In the English literature, the centromeric haplotype is called a cenhap (cenhap).
The researchers were able to identify cenchaps in fruit flies. They then used the same method to analyze human centromeric nucleotide sequences from the 1000 Genomes Project database. In the X chromosome alone, several cenchaps have been found that characterize the genetic lineage of a person for half a million years. In the 11th chromosome, a haplotype was found that the indigenous people of Africa do not have. It originated 700 thousand years ago, when the ancestors of Neanderthals separated from the line of human ancestors. And the centromere of the 12th chromosome contains an even older archaic haplotype originating from an unknown ancestor.
Humans have about 400 genes encoding olfactory receptors, with 34 of them located within the centromere of the 11th chromosome. Researchers believe that Neanderthal DNA has determined the ability of modern humans to sense certain smells.
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