Let’s talk about semen because it’s important. We already knew that the quality of sperm, for example, is directly related to 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 advertised that “aging” has more consequences than it seems. It is not only that, with age, sperm accumulate mutations; the percentage of sperm with mutations continues to rise.
This profound finding could change many of the things we thought we knew.
Understanding the Research
What exactly have they done? The research team sequenced semen samples from individuals ranging in age from 24 to 75 years old . They discovered that the process of accumulating mutations is not merely a question of biological wear and tear; rather, it involves an intriguing combination of random chance and positive selection.
The researchers found evidence of “winning” variants occurring in the testicles. The study concludes that it “demonstrates a 2–3× risk of known causal mutations with age and estimates 3–5% of sperm having a pathogenic mutation in middle-aged and older men.”
While these numbers may seem low at first glance, they represent a significant shift in our understanding.
Shifting Paradigms
The paradigm? It is not just that the older you are, the more mutations you have; these mutations compete with each other and thrive within the testicle due to a phenomenon known as intratesticular positive selection . This suggests that the risk window expands beyond just simple annual arithmetic increases.
For years, society has placed the burden of delayed parenthood squarely on women. In a simplistic—and now understood to be hasty—way, public debates have largely focused on women’s reproductive planning as the primary factor. Healthcare scientists have often defined risk profiles predominantly according to maternal age.
Yet, we must acknowledge that men have their share of responsibility as well.
What Lies Beneath the Surface?
What is hidden in the sperm? Although, as I must emphasize, the risk remains low, we cannot overlook the increased presence of variants associated with neurodevelopmental disorders and developmental syndromes , which alters the larger picture. The reality is that, despite the existing knowledge, we are still quite uninformed.
This lack of comprehensive understanding poses a significant issue, especially considering the demographic trend towards delayed parenthood is becoming more universal across societies worldwide. The age at which people are choosing to have children continues to rise, and understanding the implications of this shift is crucial.
Image | Quinn Dombrowski
In Xataka | Having many children sounds great as a way to preserve the species. Until you start passing genetic mutations.