Hierarchical regression analyses: Variables predicting genetic vectors and number of children (in parentheses) for males (N = 36).

*p**pAge, age2 were entered as control variables. The effects of height and weight were also removed from handgrip strength before the analysis. Fundamental frequency and handgrip strength were entered as target variables (bold). Genetic vectors composes of the total number of surviving children plus the number of grandchildren (halved because of genetic relatedness), or (number of children + (.5×grandchildren)).