Fathers who wait until they're almost 40 to have children may provide a unique benefit to their offspring: longer lives.
Children of older fathers, those in their late 30s to early 50s, inherit longer telomeres, caps at the end of the chromosomes that protect them from degeneration, according to a study Monday in the Proceedings of the National Academy of Sciences. Longer telomeres seem to promote slower aging and may mean a longer lifespan for these children, the study said.
Previous research has shown that the older a man is when he reproduces, the more likely the children are to carry spontaneously arising mutations, which can produce disorders like autism. Some research has suggested that children of older fathers also have lower intelligence scores than those born to younger men. Monday's study suggests late fatherhood isn't all risk, said Dan Eisenberg, a study author and doctoral student at Northwestern University in Evanston, Ill.
"Most literature also suggests risks from paternal age and this is intriguing, in part, because it stands in contrast to that," Eisenberg said in a telephone interview. "We don't really know, on balance, what the net effect is."
The longer telomeres may delay sexual development, and direct the body's energy into maintaining itself and staying healthy, he said. The late fatherhood may serve as a signal that mortality rates are low, Eisenberg said. The benefit was also seen in grandchildren of men who became fathers at later ages.
The correlation held regardless of whether the families were rich or poor, the study said.
Damaged telomeres cause cells to stop dividing, stem cells to become dormant, organs to atrophy and brain cells to die. As most cells age, the telomeres become shorter and shorter. This isn't the case for sperm, where telomeres lengthen with age. The men may be passing the longer telomeres to their children, boosting their lifespan.
On average, American men have their first child at25, according to a report from the Centers for Disease Control and Prevention.
The study looked at 2,023 children in the Philippines. There weren't differences in telomere length between the boys and girls of the same generation, the authors found. The study was funded by the National Science Foundation, the National Institutes of Health, and Northwestern University.