Women, not men, ensure the
success of future generations, work suggests.
Grandmothers surviving beyond the menopause appeared to increase
the likelihood that their own children went on to have children,
a Sheffield team found.
Yet grandfathers had very little influence on their offspring's
reproductive success, Proceedings of the Royal Society B reports.
But experts were quick to stress that both grandparents play
a vital role in families and society.
The Sheffield University authors reason that women thrive
following the menopause from caring for their own children and
grandchildren.
In their study, grandmothers gained two extra grandchildren
for every 10 years they survived beyond the menopause.
This link was not found with aged granddads, however.
Instead, the scientists say the "evolutionary" argument for
a man's survival to a ripe old age is to continue to churn out
sperm and procreate.
Sheffield's Dr Virpi Lummaa and Dr Andrew Russell, with the
help of Finnish colleagues from the University of Turku, looked
at Finnish church records spanning from 1719 to 1839 to examine
the family histories of 361 men and their 2,227 offspring and
the complete survival history of their 4,683 grandchildren.
They chose this population for their study for a number of
reasons - it included men from all social classes and different
geographical regions in a strictly monogamous society - plus
the records were mandatory and therefore should be accurate.
Dr Lummaa said: "We have carried out previous research on
the benefits of grandmothers but we wanted to get the full picture
by looking at grandfathers as well.
"The results suggest the long lifespan in human men has not
benefited their adult offspring's reproductive success, even
though grandfathers are much valued today.
"It is more likely that longevity in men is related to their
ability to have their own offspring even at advanced ages."
A spokesman from Help the Aged said: "Grandparents are an
enormous asset for any family.
"In financial terms, they provide billions of pounds worth
of childcare each year.
"For many families, grandparents mean the parents can go back
to work.
"The active role of grandparents has a clear and obvious value
in the growth and health of families."
A spokesman from the Family and Parenting Institute said being
a grandparent could offer a new lease of life.
"When people retire they look for a purpose. Being a grandparent
can be very rewarding. Grandparents can have a very strong relationship
with their grandchildren which is beneficial to all.
"Grandchildren often describe their grandparents as 'fun',
'caring', 'active' and 'up to date'. Being viewed as this means
they are more likely to view themselves in the same way."
