How Late Fatherhood Harms Children
Middle-aged males make their children age faster
Kirill Stasevich, "Science and Life"
Biologists and doctors have been studying the relationship between the age at which parents decided to have a child and the health of children for a long time. For quite a long time, more attention was paid to late motherhood here – apparently, due to the fact that the mother should not just conceive a child, but also bear it, and if some problems have accumulated in the female body with age, then it is more likely that these problems will affect children as well.
However, then data began to appear that the age of fathers also plays a role. For example, there are medical studies that say that the later a man has a child, the more likely it is that the child will have mental problems in the form of bipolar disorder, attention deficit disorder, autism, suicidal tendencies, etc.
Dan Ehninger and his colleagues from the German Center for Neurodegenerative Diseases and a number of other scientific centers in Germany decided to study the relationship between late fatherhood and the state of offspring in an experiment (Laboratory Study Shows that Father's Age Can Affect Offspring Lifespan). They received mice from young and old males; the young were four months old, the old were twenty–one months old. The female mothers in both cases were young, four months old, and all the parents belonged to the same genetic line, that is, they had all the genes in the same variants.
The cubs were evaluated according to thirteen parameters that allow assessing the aging of the body; among these parameters were characteristic changes in tissues and organs, and changes in proteins that protect cells from oxidative stress, etc. The mice grew up in the same conditions and never communicated with their fathers. However, by the nineteenth month of life, it turned out that the cubs from older fathers showed signs of aging more strongly, and in general they lived two months less – quite a long time for mice – than their mates from younger males. It turned out that the mice from the males "aged" aged faster.
Figure from the article in PNAS – VM.
One could assume that it's all about mutations – as you know, sperm cells in males are produced throughout life, and over time, more and more genetic defects appear in the DNA of sperm progenitor cells, which repair systems do not correct, and these genetic defects end up in ready-made male germ cells.
Aging is associated with the accumulation of mutations, and perhaps mutations from old fathers caused the DNA of offspring to mutate faster. However, as stated in an article in PNAS (Xie et al., Epigenetic alterations in longevity regulators, reduced life span, and exacerbated aging-related pathology in old father offspring mice), mutations accumulated at the same rate in mice from young males and in mice from old males. (In any case, as the authors of the work clarify, they could not find any difference here with the methods of analysis that they used.)
But at the same time, there was a clear difference in epigenetics – this is the name of a whole complex of molecular mechanisms that permanently change the activity of certain genes. In this case, we are talking about DNA methylation, when methyl chemical groups are sewn onto DNA, which is why the genes on which these groups have fallen begin to work stronger or weaker. Epigenetic modifications work for a very long time, and they again change with age. It turned out, on the one hand, that in mice from young males and in mice from middle-aged males, the pattern of methyl tags on DNA differs. On the other hand, these modifications were quite similar in old males and their offspring, and the modifications were on those genes that affect life expectancy and are associated with various age-related pathologies. It looked as if fathers had pre-configured their children's genetic activity for old age.
However, it remains to be seen exactly how molecular old age is inherited, not to mention the fact that the "mouse" results need to be somehow tested on humans. If our mechanism turns out to be about the same as that of rodents, then we can think of some medicine that will suppress the transmission of old age by inheritance and allow men to have children at any age.
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