MAXIMUM LIFE-SPAN PREDICTIONS FROM THE GOMPERTZ MORTALITY MODEL

This study examined, maximum life span predictions obtained with the G ompertz mortality rate model, which assumes that there is a constant r ate of acceleration in the age-related mortality of adult populations. The influence of population size N on the maximum life span (t(max)) was shown to be small, because the numeric impact of N is reduced to l n/[ln(N)]. In contrast, the Gompertz exponential mortality coefficient alpha has much more influence on the t(max), which varies as l/alpha. Examination of select mammals and birds showed that t(max) as reporte d for local populations agrees very well with that calculated from mor tality rate coefficients for these local populations. However, the t(m ax) as reported from the world literature, which is designated here as the ''world record,'' shows major discrepancies for some species from the predicted t(max) based on the local population. We demonstrate th at these discrepancies are not due to population size, but represent o ther factors that may include genotype, diet, and environmental danger s. Potential increases in human t(max) will depend mostly on slowing t he age-related acceleration of mortality. If the degree of mortality r ate slowing achieved in rats by diet restriction is applied to humans, then the median human life expectancy would approach the present t(ma x) of 120 years.