Gompertzian mortality derived from competition between cell-types: congenital, toxicologic and biometric determinants of longevity.

Gompertz-Makeham kinetics of population mortality is derived in terms of competition between hypothetical life-prolonging and life-shortening regulatory elements (cells) interacting in each organism by generalized Volterra-type competitive exclusion. The model is developed on two levels, the first applicable to homogeneous populations, and the second, a statistical generalization, applicable to inhomogeneous populations. It offers a natural classification of effects of exogeneous agents on longevity, including hormetic and paradoxical effects of toxic substances, thus relating to problems of risk assessment by extrapolation from high to low doses. Two applications, concerning the effects of radiation on mice and Drosophila imagos, respectively, are used to illustrate the flexibility of the model in the analysis and interpretation of observational data.