Delaying fatherhood may offer survival advantages, say scientists who have found children with older fathers and grandfathers appear to be “genetically programmed” to live longer. The genetic make-up of sperm changes as a man ages and develops DNA code that favors a longer life, a trait he then passes to his children.
Dr Dan Eisenberg and colleagues from the Department of Anthropology at Northwestern University studied telomere inheritance in a group of young people living in the Philippines. Telomeres, measured in blood samples, were longer in individuals whose fathers were older when they were born. And since men pass on their DNA to their children via sperm, these long telomeres can be inherited by the next generation.
The telomere lengthening seen with each year that the men delayed fatherhood was equal to the yearly shortening of telomere length that occurs in middle-aged adults. Telomere lengthening was even greater if the child’s paternal grandfather had also been older when he became a father.
Although delaying fatherhood increases the risk of miscarriage, the researchers believe there may be long-term health benefits. Inheriting longer telomeres will be particularly beneficial for tissues and biological functions that involve rapid cell growth and turnover – such as the immune system, gut and skin – the scientists believe.
And it could have significant implications for general population health. As paternal ancestors delay reproduction, longer telomere length will be passed to offspring, which could allow lifespan to be extended as populations survive to reproduce at older ages.
Prof Thomas von Zglinicki, an expert in cellular ageing at Newcastle University, said more research was needed. “Very few of the studies that linked telomere length to health in late life have studied the impact, if any, of paternal age. It is still completely unclear whether telomere length at conception (or birth) or rate of telomere loss with age is more important for age-related morbidity and mortality risk in humans. The authors did not examine health status in the first generation offspring.”
It might be possible that the advantage of receiving long telomeres from an old father is more than offset by the disadvantage of higher levels of general DNA damage and mutations in sperm, he said.