Studying Grandma's Longevity

[Guest guest]

Interesting but personally I think this is a lot of hooey.........

Humans are unusual among species in that women often live for many years

after they have lost the ability to bear offspring. That has created a

puzzle for evolutionary biologists, who believe that the main reason any

creature exists is to pass on his or her genes.

Now, a team of scientists has produced new evidence supporting the

" Grandmother Hypothesis " for why women live long after their ability to

reproduce has ended.

Mirkka Lahdenpera of the University of Turku in Finland and colleagues

examined multi-generational demographic data from Finland and Canada

and found that women who live the longest tend to have the most

grandchildren.

That suggests that their longevity improves the odds that their genes will

continue for generations by enabling them to hang around long enough to

help their children to produce their own offspring earlier and more

frequently, the researchers concluded.

" Our results lend strong support for the hypothesis that prolonged female

post-reproductive lifespan is adaptive -- to our knowledge, revealing for

the first time the substantial fitness benefits that females accrue by

living beyond reproductive age, " the researchers wrote in the March 11

Nature.

As further support, the researchers also found that grandmothers were

more likely to die around the time their daughters reach menopause --

essentially when grandma's job is done:

" That mortality rates accelerate from the time that offspring begin to

terminate reproduction suggests that selection for post-reproductive

longevity is deferred only until a woman's own offspring finish

reproducing and can become the future generation of helpers. "