>>What use it is evolution-wise for adults to live beyond the age where
>>their children have become independant adults?

Peter wrote:
>1)To take care of the grandchildren while the parents are out
> hunting or gathering.  2) To pass on the wisdom, knowledge and
> perspective that follows with old age - all which is vital for the
>survival of the tribe.

I would add that humans are unique in the length of time it takes to
raise & educate children, and I believe it is Steven J. Gould who
has proposed the above as an explanation of why having humans live
into grandparenthood is an evolutionary adaptation of great survival
value.  There are also some species which either appear not to age,
or to age at a glacial rate.  Nature does not always require that
species age (or age relatively rapidly).  But aging is a vital means
of controling population densities, something which directly relates
to food supplies.  So if the food supply is minimal, the lifespans
will elongate to ensure reproduction & survival.  This is why it is
important to try to limit food intake & hence extend your lifespan.

--Doug Schwartz
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