BIODEMOGRAPHIC TRAJECTORIES OF LONGEVITY

Old-age survival has increased substantially since 1950. Death rates d ecelerate with age for insects, worms, and yeast, as well as humans. T his evidence of extended postreproductive survival is puzzling. Three biodemographic insights-concerning the correlation of death rates acro ss age, individual differences in survival chances, and induced altera tions in age patterns of fertility and mortality-offer clues and sugge st research on the failure of complicated systems, on new demographic equations for evolutionary theory, and on fertility-longevity interact ions. Nongenetic changes account for increases in human life-spans to date. Explication of these causes and the genetic license for extended survival, as well as discovery of genes and other survival attributes affecting longevity, will lead to even longer lives.