Re: The ultimate cause of aging

dkomo wrote:

"The basic reason why survival and reproduction decline with age is that
selection acts more weakly on later ages. Imagine an organism that does
not senesce, that is, that maintains itself with the same rate of
survival and reproduction indefinitely. It will still suffer accidental
mortality and so, on average, reproducing early will produce more
offspring than deferring reproduction until later; death might strike
first. Therefore, natural selection acts more strongly on variations
that act early in life and acts more and more weakly on late-acting
acting variations (see Box 20.2). If, as a result, senescence starts to
evolve, then there will be a feedback, so that selection on later ages
becomes even weaker. In the extreme case, where an organism such as a
salmon reproduces only once, there is absolutely no selection on
subsequent survival."

Nicholas Barton et al, _Evolution_, p. 562

That's one theory. However, aging has many causes - e.g. see:

http://en.wikipedia.org/wiki/Reliability_theory_of_aging_and_longevity
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