Document Type



The question of selection (modal or balanced, directional, destabilizing) in fertility for specified anthropometric traits of both parents (mothers 40 years or over) is examined in a sample of Mexican families. Mean number of children tends to be greater in the modal type of 10 parental traits, and directional in 10 other parental traits. Although the differences are not statistically significant, it is suggested they may be biologically significant since they exceed one percent. Variance analyses (F- ratios) are calculated for mothers and fathers in relation to fertility and an­thropometric traits, as well as two-way interaction in this regard between mothers and fathers. The discussion emphasizes the role of non-biological factors in the measure of fertility in humans.