On the speed of demographic aging

Gustavo De Santis, Università di Firenze
Giambattista Salinari, Università degli Studi di Sassari

Vaupel has recently advanced the hypothesis that the rate of aging may be a “basic biological constant” for humans. Although logically strong and consistent with the “mortality plateau” at very old ages, this hypothesis was basically rejected by the most recent estimates based on the Gamma-Gompertz model. In this paper, however, we propose a new model (EGG, or Extended Gamma-Gompertz), based on the idea that aging increases gradually with age before converging to a constant value. In an application to the cohorts born between 1820 and 1899 in five countries with high-quality data in the Human Mortality Database, the EGG model fits closely with the empirical evolution of mortality over time and proves consistent with a modified version of Vaupel’s hypothesis: the age schedule of the rate of aging may be a biological constant.