A Two-Process Mortality Model with Extensions to Juvenile Mortality, Population Dynamics and Evolution

James Anderson, University of Washington
Ting Li, Renmin University of China

A vitality framework partitions mortality into intrinsic and extrinsic parts representing age-dependent loss of survival capacity and environmental challenges to the capacity. We extend a previous 4-parameter model suitable to modeling adult mortality to a 6-parameter form that includes vitality challenges to early life and thus is suitable for modeling survival from birth. The framework merges force of mortality and stochastic vitality models and shifts the perspective from explaining how the force of mortality changes with age to how the underlying intrinsic and extrinsic vitality processes change. Extensions of the model to population ecology and natural selection are discussed.