Gender differences in height: An evolutionary perspective

Homo sapiens (H. sapiens) exhibits growth characteristics not observed in other mammals, including other primates. Both male and female H. sapiens experience pubertal growth spurts and are not sexually dimorphic in adult stature. These unique growth characteristics must have evolved to benefit the reproductive success and survival of the species. The H. sapiens childhood is relatively protracted, and the pubertal growth spurt may be a compensatory measure to attain adult size in a relatively short time. Because reproductive patterns of H. sapiens have evolved away from a male-dominated social structure, large male size no longer confers a reproductive advantage. The relatively large female size of H. sapiens might have evolved to support the birth of offspring with ever-increasing cranial characteristics. Growth in H. sapiens depends largely on GH-dependent STAT5b regulation of IGF-I expression. STAT5b in other mammals contributes to growth in males only. Although speculative, the loss of sexual dimorphism in H. sapiens may reflect a progressive dependence on STAT5b to control growth.