Grans not grandpas 'extend life'
Last Updated: Saturday, 28 July 2007, 01:58 GMT 02:58 UK
Grandparents share a special bond with their grandchildren
Women, not men, ensure the success of future generations, work suggests.
Grans 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.
Grandparents are an enormous asset for any family
A spokesman from Help the Aged
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."