Population biology of human aging: methods of assessment and sex variation.

Biological age, as assessed by osteographic measurements of hand bones from radiograms, was estimated in about 7000 individuals belonging to 32 ethnic groups and samples and to 2 major human groups (Europeans and Asians). Individual ages in the total group varied between 16 and 99 years old. Our biological age measure is strongly correlated with chronological age of the individual (Pearson's r = 0.78-0.80, p < 0.001), which renders the correlation amenable to fitting with a two-stage stochastic model. The following parameters of the model were estimated accordingly: t0 is the minimal age at which initial bone changes occurred, q is the probability that an individual will first develop involutive bone change at age ti > t0, and B is the rate of aging (bone change) per unit time. The parameters varied considerably within different populations, but only a few samples showed statistically significant sex differences for all three parameters. However, B was consistently higher among women than among men. Apart from that, the distributions of the observed biological age estimates adjusted on the expected biological age values reveal no differences between men and women in any of the studied samples or in the total population.