Scientists say they've found a link between long life and late childbirth.
A new study of genealogical records from Utah pioneers and settlers of
Montreal, Canada, reveals that women who had babies naturally in their 40s
and 50s lived longer than other women.
The brothers of those women also lived longer.
Such findings suggest the same genes prolong lifespan and female fertility
and lead researchers to believe there is a strong genetic component for
longevity in humans, said Ken R. Smith, professor of family and consumer
studies at the University of Utah.
"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," he
said.
Smith is the lead researcher in the study that will be published June 10 in
the Journal of Gerontology: Biological Sciences. It already can viewed
online at the journal's Web site.
Evolutionary biologists long have argued that survival and reproduction are
intrinsically linked, Smith said.
"So, the novel finding in this paper is discovering this link in humans
before modern contraception."
The team of researchers from the U. of U., University of Western Ontario,
and the University of Montreal also considered the wives of the brothers to
determine whether the longevity could be attributed to environmental
conditions, such as food, shelter and disease. But the wives --- who were
not blood relatives --- did not lead longer lives.
That, too, points to a strong genetic component for longevity, Smith said.
If environmental factors were as important, the spouses should live as long
as their husbands.
The Utah pioneers were largely British and Scandinavian, while the Montreal
settlers were French. But the research team found the same trends in those
very different populations, revealing the thesis that links late motherhood
to longevity is sound, Smith said.
Pioneer women used no contraception and typically had large families. In
many cases, they gave birth until they were no longer able. The study
considers reproduction in pioneer women as an indicator of overall health,
Smith noted.
"The important advantage of looking at ovaries is that it's like a clock
that runs out sooner than the individual, as opposed to organs like the
lungs and heart."
In pioneer women, the ability to give birth in mid-life is a preview of
prospects for longevity, Smith said.
In modern women who use contraception, onset of menopause may be a similar
indicator, Smith said, although that was not part of the study.
"Once we have this information, we can take action accordingly," he said.
The research is part of an ongoing study funded by a grant from the National
Institute of Aging that seeks cues and indicators for how long we will live.
Eventually, scientists hope to locate genes responsible for aging.
"We all want to live long lives," Smith said. "As long as we can be
healthy."
