how natural selection “controls” whether or not we have children

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“During the days that my meetings take place you can stay for dinner with me, as long as you refrain from your painful disputes, which annoy meas well as all your complaints about this stupid world and human misery, because all this makes me have a bad night and have bad dreams, and I like to sleep well”. It was December 13, 1807 and the author of those lines was the mother of the famous German philosopher Arthur Schopenhauer. In fact, the letter was written to him, to her son.

Schopenhauer was (and in the light of that letter it even seems reasonable) one of the great exponents of the antinatalism; a stream of thought that obviously it’s in vogue. Because although it is true that the philosophical, political, or demographic positions contrary to reproduction (and, by extension, the birth of new human beings) are very old, the truth is that in recent years they have experienced a kind of revival in the heat of decline and problems related to climate change.

Today, however, we are not going to talk about anti-natalism as an intellectual movement; but of a whole enormous series of cognitive and behavioral traits that relate (unexpectedly) the probability of not having children with a certain genetic base: a kind of “psychological, temperamental antinatalism” and its genetic component.

Genes that cannot mutate

Sangharsh Lohakare Iy7qyzos1bo Unsplash

Sangharsh Lohakare

Let’s put things in context: there is a whole set of genes (some 3,000, at least) that are selectively restricted. That is, for various reasons, do not tolerate harmful genetic variation well. This causes those variations to be quickly eliminated from the population through natural selection. The most direct way for natural selection to do it, if I may use the expression, is to “associate” these basic genes with serious disorders that “shorten life expectancy, cause infertility, or affect cognition or behavior.”

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However, there are about two thirds of restricted genes that are not related to any type of genetic disease. That is, these genetic variations disappeared from the population even though the people who carried them were in perfect health. This has had researchers very concerned, who did not understand very well how this could happen.

Now a study of matthew hurles and your team has analyzed genomic and phenotypic data from 340,925 people from the UK Biobank (people aged between 39 and 73 years; to be considered old enough to have had the opportunity to reproduce). What they have found is that, indeed, people who have a harmful variant of any of these genes have a small but significantly higher probability of not having children than those who do not. Especially the men.

What’s going on here?

That’s the interesting thing, why? The analyzes of the Wellcome Sanger Institute suggest that male individuals with these variants in restricted genes are more likely to display cognitive and behavioral traits than reduce your chances of finding a partner (and, if found, to reproduce). Some were already clear (lower scores on cognitive tests or greater risk of developing mental illnesses such as depression), but others are more subtle and have to do with certain personality characteristics or even with ideas and/or ideological positions.

This is not surprising. There are many studies that provide evidence in favor of a direct relationship between personality and political ideology (or, at least, certain political-ideological propensities). In fact, traits related to political progressivism or with conservatism they are well known. The work that Nature magazine publishes today has not analyzed this in depth, but it does lay the groundwork for future study.

This obviously does not mean that all those with antinatalist positions have mutations in the restricted genes. Far from it: genetics doesn’t work like that. In fact, the authors point out that Other features (such as sociodemographic factors and personal choice) are more important in determining whether or not a particular individual has children. However, it does provide important clues to understand how and why these harmful variants disappear from the population.

After all, say the authors, at the aggregate level (ie, over several generations and at the population level), associations between harmful mutations in restricted genes and reduced reproductive success may explain about 20% of the deaths. selective pressures acting on restricted genes. And this (even taking into account all the limitations of the work) are big words.

Image | Christian Bowens

“During the days that my meetings take place you can stay for dinner with me, as long as you refrain…

“During the days that my meetings take place you can stay for dinner with me, as long as you refrain…

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