Heart disease and sexual selection
Geneticists have uncovered the link between sex and heart disease
Geneticists have uncovered a link between coronary heart disease and procreation success, which explains why heart and vascular problems are the main cause of death today, according to an article published in the journal PLoS One (Byars et al., Genetic loci associated with coronary artery disease harbor evidence of selection and antagonistic pleiotropy).
"According to Darwin's theory, variants of genes that help an individual survive or continue their kind should spread throughout the population, and the "bad" versions of them should gradually disappear. From this point of view, the existence of coronary heart disease is completely inexplicable, and we tried to understand why this is so, given its danger to human health," says Sean Byars from the University of Melbourne (in a press release Human genes for coronary artery disease make them more prolific parents – VM).
The development of almost all multicellular living beings is controlled by two factors – natural and sexual selection. In the first case, evolution is conducted by changing environmental conditions, and in the second case, intraspecific competition for the opportunity to continue their kind. In this struggle, the most "bright" individuals win, which leads to the appearance of such useless ornaments as peacock tails or rooster combs, which do not help, but hinder survival.
The reasons for the existence of sexual selection are still a matter of debate among scientists – some biologists believe that it helps populations to be prepared for sudden changes in conditions, while others believe that such competition protects species from degeneration and supports their competitiveness in the evolutionary "arms race".
Byars and his colleagues discovered an unusual connection between these "halves" of evolution, which made a person genetically and evolutionarily predisposed to developing heart and vascular problems in old age by studying DNA variations of several hundred inhabitants of Europe, Africa and Asia associated with coronary heart disease.
This analysis led to unusual conclusions – it turned out that mutations that contribute to the development of such health problems in old age did not disappear from the gene pool, but on the contrary, spread and accumulated in it. In other words, carriers of negative changes in the structure of genes that lead to the development of ischemic disease left more offspring and continued the race more often.
Such a "violation" of the theory of evolution, according to Byars and his colleagues, is associated with sexual selection – some changes that increase the likelihood of heart problems in old age, apparently helped their owners attract the attention of representatives of the opposite sex or increased the chances of conceiving a child.
This was supported by the fact that many of these genes were most active in the genitals or glands, and also determined the time of puberty, the time of the onset of menstruation, menopause and the likelihood of survival after childbirth.
"Evolution seems to have worked out an interesting compromise, thanks to which coronary heart disease begins to manifest itself only at the age of 40 or 50, when the time for procreation has already passed. All this does not mean that women who give birth to a large number of children die more often from heart problems – we are just saying that coronary artery disease is a byproduct of high fertility of people," explains Byars.
All this, as the scientist concludes, suggests that coronary heart disease and other problems of the cardiovascular system are widespread today not because of the development of civilization and environmental degradation, but for deep evolutionary reasons related to how our ancestors survived and multiplied in the distant past.
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23.06.2017