Age-Structured Populations

Life, in part, is a process of aging; individuals are born, they mature, and at some point they die. The aging process has a direct effect on individual probabilities of survival and reproductive activity, as well as on total population size. For example, fecundity is zero until the age of reproductive maturity; it then increases and remains high through adulthood, finally declining in old age. Mortality, on the other hand, is usually high in the very young and very old individuals, and lower for adults. Any detailed description of population dynamics must take the age- dependent nature of these variables into account.