Why do organisms age?

Abstract

Abstract The study of the underpinnings of ageing provides insight not only into the kinds of genetic factors that influence the ageing process, but also into the physiological mechanisms influencing ageing and longevity. Notions that ageing was necessary to create living space for future generations, or to facilitate turnover of the population, are generally unsound. Instead, ageing is thought to have its evolutionary origins in how the force of natural selection declines with age, the later portions of the lifespan being under indirect evolutionary control. The most widely supported explanation of why organisms age is the disposable soma theory. This posits that, under pressure of selection to make the best use of available resources, genomes evolved to put only enough effort into cellular maintenance to keep the individual in sound condition through the period that it might normally have been expected to survive and reproduce in ancestral, wild environments.