Abstract

Human life expectancy increased extraordinarily during the 20th century worldwide, first because of child mortality reduction and then because of reduced mortality in middle and old age. This phenomenon is expected to continue, bringing about substantial social and economic consequences. Ageing has been viewed conventionally as animmutable biological event. However, there is current evidence that the biological processes of ageing, which generatemost age-related diseases, can be delayed. Even if genetic modifications are not yet possible, changes in diet, physical,and mental activity, along with the control of modifiable environmental factors, may change the susceptibility to disease,increasing not only the number of living years but also the quality of these extra years.