The evolutionary context of human aging and degenerative disease

This chapter reviews evidence on human aging. Humans are the longestlived primate. Trade-offs modulate human life span. 'Longevity genes' that protect against disease may slow the aging processes in humans and in model organisms, but they are not at high frequency in human populations, probably because they reduce fitness in early life. Insights into their protective mechanisms could yield pharmaceuticals that extend human health, but close attention would have to be paid to side effects, for the effects on humans of genetic alterations that extend life in laboratory mice are not pleasant. Genetic alterations in the GH/IGF-I axis appear at best not to extend life and at worst to shorten it, with many detrimental impacts on health. It would help to have a small, short-lived, primate research model in which anti-aging therapies developed from mouse experiments could be evaluated before testing them on humans.