Growth and hormone characteristics of pubertal development in the hamadryas baboon.

The semi-longitudinal collection of growth measurements in male and female hamadryas baboons has enabled documentation of the timing of puberty and the development of sexually dimorphic growth patterns in body weight, crown-rump length (CRL), limb lengths, and muscle mass. In addition, another sexually dimorphic characteristic appears to be the presence of a pubertal growth spurt in body weight, and possibly CRL, in male but not female baboons. Serum testosterone levels rose during male development; however, there was a progressive decrease in dehydroepiandrosterone sulfate levels indicating the absence of adrenarche. Insulin-like growth factor-I (IGF-I) and its major binding protein, IGFBP-3, both rose during pubertal development; however, a simultaneous rise in the IGF-I:IGFBP-3 molar ratio suggests other factors may enhance the bioactivity of IGF-I during puberty. A distinct rise in serum osteocalcin levels was also associated with puberty in male baboons. These growth and hormonal changes during puberty in the hamadryas baboon indicate that this species provides a close primate model for human puberty.