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I’ve been doing some research to figure out how natural selection could evolve aging. I found an article which theorizes that “aging is a non-adaptive process in which the genes that influence the rate of aging either do not affect fitness or have been selected due to beneficial effects early in life.”

Another website, The International Longevity Organization (pdf) declares that “Most gerontologists believe there is no such gene (that causes aging) in most species, because a gene that promotes aging would most likely decrease reproductive fitness and therefore would be subject to negative selection.” On the website, they waive the p53 gene off as a tumor suppressing gene.

However, the Boston University website (pdf) has a very different view and suggests a genetic biological clock (telomere length, telomerase function) and various classes of aging genes, including the p53. But it doesn’t suggest how such genes might have been naturally selected.

There is also this website’s explanation for the evolution of aging and death:

Now, if you are likely to die around the age of 25 by external causes, there is little advantage in spending a lot of resources on combating the effects of aging, so that you might theoretically live for 1000 years. That is why we might expect that in the trade-off between early reproduction and long-time survival the genes would tend towards the former pole, making sure that sufficient off-spring is generated by the age of 25, rather than trying to extend the maximal age beyond 120 years (the apparent maximum for humans). And that of course ties the aging genes to reproduction, directing the explanation to resisting the effects of aging instead of what is causing it. They use a fruit fly experiment as an example where delaying reproduction causes longer life.

So much for my research. I’m curious now what your position is as to how aging and death evolved by natural selection and what we should expect to see in the fossil record to substantiate it.

I’m curious now what your position is as to how aging and death evolved by natural selection and what we should expect to see in the fossil record to substantiate it.

Evolutionary models of aging are supported by population studies and by molecular biology.

There is obviously a selection bias toward the reproductive years in a lifespan. Mortality is also a tradeoff against cancer. The programmed cell death you allude to is part of a tightly controlled network of genes that guard against damage to cells that would lead to uncontrolled growth. These are two effects fall under the antagonistic pleiotropic models. And they make perfect sense. But there is greater support for the model that aging is a result of mutational and cellular damage. It's a surprise that we live as long as we do and the pleiotropic effects that may contribute to cellular and organismal senescence don't control lifespan as much as the simple inability of stress and mutational repair mechanisms to extend lifespan.