Negative senescence is characterized by a decline in mortality with age after reproductive maturity, generally accompanied by an increase in fecundity. Hamilton (1966) ruled out negative senescence: we adumbrate the deficiencies of his model. We review empirical studies of various plants and...

The evolution of different life history strategies and thus different ageing patterns essentially depends on the nature of the underlying trade-offs between survival and reproduction. To fully comprehend ageing, we need to understand these trade-offs.

As one aspect of the complex feature of longevity, gene-sex interaction plays an important role in influencing human life span. With advances in molecular genetics, more studies aimed at assessing gene-sex interaction are expected. New and valid statistical methods are needed. In this paper, we...

Cause-specific mortality data on Danish monozygotic (MZ) and dizygotic (DZ) twins are used to analyze the influence of smoking and body mass index (BMI) on heritability estimates of susceptibility to coronary heart disease (CHD). The sample includes 1209 like-sexed twin pairs born between 1890...

Twin studies provide an important possibility for demographers to analyze patterns of heritability and to estimate structural models with controls for endowments. These possibilities are increasingly used in the context of fertility and related behaviors. A close congruence between the fertility...

A mixture model in multivariate survival analysis is presented, whereby heterogeneity among subjects creates divergent paths for the individual's risk of experiencing an event (i.e., disease), as well as for the associated length of survival. Dependence among competing risks is included and...

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We analyze causal effects of conditions early in life on the individual mortality rate later in life. Conditions early in life are captured by transitory features of the macro environment around birth, notably the state of the business cycle around birth, but also food price deviations, weather...

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Hamilton quantified the force of selection on an age-specific mutation. Hamilton’s indicators of the age-specific force of selection always decline with age. This result is of profound importance to the theory of the evolution of senescence. Here I derive alternative indicators within...