Population biology of human aging: Ethnic and climatic variation of bone age scores

Hand radiograms for osseographic assessment of bone-aging status were taken from more than 7500 individuals living in 32 different geographic localities and belonging to 20 ethnic groups. Multiple regression analysis was used to evaluate possible associations between bone-aging parameters and number of climatic factors. To determine whether population differences in bone-aging estimates were related to linguistic, ethnic, or genetic differences among the samples, we performed a matrix correspondence analysis. Euclidean distance matrices for parameters T_M (average age at entering visual stage of bone aging) and B (the rate of bone aging per year) were tested against design matrices specifying linguistic or ethnic affiliation of the tested populations, yet no significant correlations were detected in this set of analyses. The matrix of joint genetic distances based on 10 genetic systems showed significant correlation (r = 0.48, p = 0.013) with the matrix of B differences. This suggests some genetic control in the rate of bone aging. T_M and age-adjusted bone-aging scores (Z) yielded no evidence of correlation with genetic differences among the studied populations. Multiple regression analysis, however, uncovered that 37.5% of T_M variation and 48% of Z variation could be explained by climate factors and their interactions.