Researchers have found that women who have babies naturally in their 40s or 50s tend to live longer than other women so do their family members as the same genes prolong lifespan and female fertility.
"If women in your family give birth at older ages, you may well have a chance of living longer than you would otherwise. If you have a female relative who had children after age 45, then there may be some genetic benefit in your family that will enhance your longevity," lead author Ken R. Smith of Utah University said.
For descendants of the Utah and Quebec pioneers studied, "you may be able to look at the ages when your female ancestors gave birth -- rather than just their longevity – in estimating how long you may live," said Smith, whose study is published in 'Journal of Gerontology: Biological Sciences'.
Specifically, the study involved the records of 11,604 Utah men who were born between 1800 and 1869 and who had at least one sister who lived at least to age 50; and the records of 6,206 Quebec men who lived between 1670 and 1750, and had at least one sister who lived to 50 or older.
The study didn't address how much longevity is due to genetics, but Smith says scientists believe genes account for up to 25 per cent of differences in longevity.
Smith says the study focused on the longevity of brothers rather than sisters of late-fertile women because "men's own reproductive history doesn't get in the way of assessing the role of their female relatives' fertility".