July 30, 2021

A world without males | Science

A world without males | Science



Scientists have achieved reproduction between two females, how can you read in Subject. Calm the male readers: the experiment has been done in mice, and at the moment it is not applicable to our species. But, of course, deep down we are just mice with a huge head, and the technical problems are always resolved in one way or another. Given the situation, it is inevitable to speculate about a future world without males or, at least, a world in which males are not necessary for reproduction. The research we have learned this week is important, and it is worth taking a good look at its scientific foundations before overheating the imagination. The key is in a process little known by the reading public, the genomic imprint, and we need to know what it consists of. Turn on all your neurons and keep reading.

The genomic imprint (genomic imprinting) only occurs in mammals. It consists in that a gene is active or not depending on whether it comes from the father or the mother. In that sense, it violates Mendel's laws, which do not distinguish between the parents of an individual. The phenomenon originates during the development of sex cells (ovules or sperm), and is due to "epigenetic" processes, which do not alter the sequence of genes (gatacca …), but inactivate them by other things that stick above, as the simplest of the radicals of organic chemistry (the methyl group, -CH3). This inactivation by "methylation" survives fertilization and all embryonic and fetal development.

When a gene that comes from the father is inactivated by methylation, the same gene that comes from the mother must be active (and vice versa), or otherwise the fetus will lack the activity of that gene completely, and it will not be viable. This is the profound reason why mammals, unlike other animals, can not reproduce in same-sex couples. Even if we achieve in the laboratory that a female produces sperm, and fertilize an egg with them, the same genes will be inactivated by imprinting (methylation) in the resulting embryo, and the fetus will not be viable.

The evolutionary reason why this happens is very interesting, by the way. The evolutionary interests of male and female are very different, or rather opposite. Take the human case. The investment a man makes to reproduce is minimal: five minutes of intercourse, being optimistic. The woman, on the other hand, takes nine months of gestation and a lot of energy to achieve the same purpose. Many of the genes regulated by imprinting have a direct relationship with this fact. The genes that are active of the father favor the nutrient consumption of the mother during the fetal and infant development; those who are active of the mother impose cuts in that robbery. Of course, neither the father nor the mother does this consciously: we are all evolutionary victims of our remote past.

In any case, this is the problem that scientists have now solved. In mice. And using a lot of genetic manipulations that, of course, are inapplicable to humans, at least in their current form. But the experiments reveal that there is no problem in principle for two women to reproduce. Letting the imagination fly, we can imagine a future in which men are not necessary for reproduction. But there is a consolation prize for the machirulos: men will continue to appear in every human generation, even if we have two mothers.

Although, well thought, this could also be fixed. Think about it.

* THE SCIENCE OF THE WEEK is a space in which Javier Sampedro analyzes scientific news. Subscribe to the newsletter of Matter and you will receive it every Saturday in your email, along with a selection of our best news of the week.

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