Why Dogs love people
Geneticists have found an unusual explanation for the friendliness of dogs
The friendliness of dogs is explained by the fact that virtually all "human best friends" are carriers of a special version of the so–called "elf syndrome" - mental retardation associated with chromosome rearrangement, according to an article published in the journal Science Advances (Structural variants in genes associated with human Williams-Beuren syndrome underlie stereotypical hypersociability in domestic dogs).
"This study is extremely interesting from the point of view that it supports the hypothesis of "survival of the kindest", describing the process of domestication of dogs. When these genes were damaged and rearranged in the chromosomes of wolves, their fear of humans was replaced by friendliness, and man had his first companion," Brian Hare, an evolutionary anthropologist from Duke University in Durham, commented on the discovery (in a press release Why are dogs such dotting companions? It's in their genes – ).
It is believed that man tamed dogs back in the Stone Age, long before the domestication of other animals. The time of their domestication remains unclear – there are fossil evidence of both relatively late (10-18 thousand years ago) and early (over 36 thousand years ago) domestication.
In addition, it is still unclear who "tamed" whom – dog people, or dog people. The ancestors of dogs, as evolutionists believe today, learned to live next to humans thanks to two things – the ability to digest starch contained in large quantities in boiled food, and the ability to recognize human emotions and react to them, generally imitating the behavior of a child.
Briget van Holdt from Princeton University (USA) and her colleagues found out that the latter ability of dogs is the product of unusual changes in the structure of their chromosomes, which in humans are usually associated with the development of mental retardation and an extremely high degree of trustfulness and friendliness.
This problem, the so-called Williams syndrome or "elf syndrome", as it is called by ordinary people, arises due to damage and removal of a sufficiently large section of the seventh chromosome, as a result of which both human behavior and his appearance change.
As van Holdt and her colleagues discovered, something similar happened to dogs during their domestication, only the sixth, not the seventh chromosome was damaged in future human friends. All dogs studied by scientists had damage in this chromosome, which suggests that ancient breeders unknowingly selected the owners of these mutations and allowed them to continue their kind.
Scientists discovered these unusual mutations in the genome of "man's best friends" by comparing the DNA of several dozen ordinary mongrels, purebred dogs and wild wolves and assessing how this or that individual reacted to the appearance of a person and how friendly she was.
DNA analysis and observations of the behavior of wild and domestic animals indicated an unusual thing – the friendlier the dog was, the more small mutations and large errors its genome contained. When scientists compared sets of mutations in the DNA of dogs, they found that most of these errors were concentrated on the sixth chromosome, in the vicinity of the GTF2I gene.
This gene, as biologists explain, conducts the work of several dozen other DNA sites associated with social behavior and the psyche of animals, and its damage leads to the same consequences as Williams syndrome. The removal or damage of GTF2I in the mouse genome, according to the researchers, dramatically changes the behavior of rodents and deprives them of fear of humans.
In fact, the presence of such DNA damage explains why dogs have a "childish" psyche and always react very emotionally to the actions of the owner and other people, and makes them a good example for studying what happens to the human psyche and nervous system during the development of the "elf syndrome".
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20.07.2017