We have carried the burden of reproductive delay on women. But men also have their part (and the proof is in the sperm)

Let’s talk about semen because it’s important. We already knew: the quality of sperm, for example, is directly related with the life expectancy of men. However, in recent days the situation has taken an interesting turn.

A few days ago, a group of researchers from the Sanger Institute and King’s College London advertisement that “aging” has more consequences than it seems. It is not only that, with age, sperm accumulate mutations; is that the percentage of sperm with mutations does not stop growing.

And that changes many of the things we thought we knew.

What exactly have they done? The team sequenced semen samples from individuals between 24-75 years old and They discovered that the process accumulation of mutations is not just a matter of wear and tear. There is, interestingly, a combination of chance and positive selection.

That is, he has found evidence that there are “winning” variants in the testicles. The study concludes that it “concludes a 2–3× risk of known causal mutations with age and estimates 3–5% of sperm with a pathogenic mutation in middle-aged and older men.”

The numbers are low, but the paradigm changes.

The paradigm? It is not just that the older you are, the more mutations there are, but that these mutations compete with each other and thrive within the testicle (intratesticular positive selection). This means that the risk window widens beyond the simple annual arithmetic sum.

For years, we have carried the burden of delayed parenthood on women. In a simplistic (and now we know hasty) way, the public debate has loaded thethe responsibility of reproductive planning about them. But also the health-scientist: the risk profiles were defined by the gestational age of the mother.

And yet, men also have their part.

What is hidden in the sperm. Although, as I cannot help but repeat, the risk is low, we cannot ignore that the greater presence of variants linked to neurodevelopmental disorders and developmental syndromes changes the general picture. The reality is that, despite everything we know, we know very little.

And that is a problem because, whether we want it or notthe trends are very solid: the age of having children it’s going to be delayed all over the world.

Image | Quinn Dombrowski

In Xataka | Having many children sounds great as a way to preserve the species. Until you start passing genetic mutations