Aging And Longevity In Animal Models And Humans

How many animal models are adequate to study human aging? Aging is an adaptive process performed by an integrated panel of evolutionarily selected mechanisms aimed at maintaining soma integrity. The possibility of extrapolating results from animal models to human beings has to be addressed in an ecological context. Model systems fit basic requirements of scientific research, and experimental animals show a series of advantages for the study of aging and longevity in humans. However, animal models have intrinsic constraints because they are artificial: Humans are not inbred and live in different conditions from both an environmental and a socio-anthropological-cultural point of view. Even if research on aging and longevity has been performed primarily in model systems such as yeast, worms, and flies, results obtained in humans are not only of basic importance but are also largely unexpected, probably because of the peculiar characteristics of humans (protected environment, culture, economic conditions, stochasticity). In some cases, studies in animal models or humans have led to analogous results, largely because basic mechanisms involved in aging have been conserved throughout evolution. In other cases, results are different or even opposite, as is described in this chapter. Animal models are often not sufficiently adequate for the study of human longevity, but their usefulness in achieving knowledge at different levels (molecular, cellular, physiological, behavioral) is unquestionable. Thus, it seems that the concomitant and integrated use of ad hoc models, also comparing different species, together with new in silico and high throughput strategies, will be the general framework within which studies on human aging and longevity should be performed to accelerate the identification of new determinants of healthy aging and longevity.