UNDERSTANDING AGING

A broad biological approach makes it possible to understand why ageing exists and also why different mammalian species have very different m aximum longevities. The adult organism is maintained in a functional s tate by at least ten major mechanisms, which together comprise a subst antial proportion of all biological processes. These maintenance mecha nisms eventually fail, because the evolved physiological and anatomica l design of higher animals is incompatible with continual survival. Th e lifespan of each mammalian species depends on the efficiency of main tenance of their cells, tissues and organisms, and there is much evide nce that such maintenance is more effective in long-lived species, suc h as man, than in short-lived small mammals. It is also evident that t here is an inverse relationship between reproductive potential and lon gevity, which would be expected if total metabolic resources are share d between investment in reproduction, and investment in the preservati on of the adult body. It is proposed that the eventual failure of main tenance leads to the pathological changes seen in age-associated disea se. Although we now have a biological understanding of the ageing proc ess, much future research will be needed to uncover the cellular and m olecular changes which give rise to age-associated diseases. The major aim of such research is to devise procedures to delay or prevent the onset of these diseases.