ABSTRACT
This chapter examines how evolutionary theory and evolutionary biology are being used to explain why and how we age. It looks at some historical evolutionary theories related to longevity and aging, and explores in more detail some evolutionary models. The chapter discusses August Weismann's thoughts on aging form the basis of what would later be called the trade-off hypothesis, which suggests that the cost of successful reproduction is mortality. It presents results from a few investigations that link the evolution of longevity to genes selected for reproduction. The chapter describes two theories of aging—antagonistic pleiotropic and disposable soma—that evolutionarily account for age-related decline in physiological and biological function. Evolutionary theories of aging and longevity rely on some basic principles of population genetics to better explain how life span in a population is affected by the frequency at which an allele that enhances reproduction appears in a species' genome.
