The modal age at death and the shifting mortality hypothesis

The modal age at death is used to study the shifting mortality scenario experienced by low mortality countries. The relations of the life table functions at the modal age are analyzed using mortality models. In the models the modal age increases over time, but there is an asymptotic approximation towards a constant number of deaths and standard deviation from the mode. The findings are compared to the changes observed in populations with historical mortality data. During the transition period to a shifting mortality era the population becomes highly heterogeneous and the rate of improvement in mortality is highly sensitive to these changes. By focusing in the modal age at death, a new perspective on the analysis of human longevity is revealed.