  General functions for human survival and mortality may support a possibility
of general mechanisms in human ageing. We discovered that the survival and
mortality curves could be described very simply and accurately by the Weibull
survival function with age-dependent shape parameter. The age-dependence of
shape parameter determines the shape of the survival and mortality curves and
tells the nature of the ageing rate. Especially, the progression of shape
parameter with age may be explained by the increase of interaction among vital
processes or the evolution of susceptibility to faults with age. Age-related
diseases may be attributed to the evolution of susceptibility to faults with
age.
