X-Message-Number: 2101 From: Ralph Merkle <> Subject: Optimality, mutation and the evolution of ageing Date: Mon, 12 Apr 1993 16:34:26 PDT "Optimality, mutation and the evolution of ageing", by L. Partridge and N.H. Barton, a review article in Nature, Vol 362, March 25th 1993, page 305. The abstract: Evolutionary explanations of ageing fall into two classes. Organisms might have evolved the optimal life history, in which survival and fertility late in life are sacrificed for the sake of early reproduction and survival. Alternatively, the life history might be depressed below this optimal compromise by deleterious mutation: because selection against late-acting mutations is weaker, these will impose a greater load on late life. Evidence for the importance of both is emerging, and unravelling their relative importance presents experimentalists with a major challenge. >From the article: "Because ageing reduces the genetic contributions of individuals to future generations, it is opposed by natural selection. But as Medawar first pointed out [omitted references], the natural selection that maintains survival and fertility becomes weaker through the life history. Even without ageing, organisms are at risk of death and impaired fertility from disease, predation and accidents. If the genes affecting survival and ferility are to some extent age-specific in their effects, then those that influence later life will be subject to weaker selection because, by the time they take effect, more of the original carriers will already have died or become infertile for other reasons[omitted references]." Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=2101