ORIGINAL ARTICLE: Leptin associations with age,weight, and sex among chimpanzees (Pan troglodytes)

Background Leptin is a hormone secreted primarily by adipocytes, a lipostatic signal to the hypothalamus, and is often correlated with adiposity. Associations between leptin, age, and development are unknown in human’s closest evolutionary relative, the common chimpanzee (Pan troglodytes). Methods Serum leptin was assessed cross sectionally in association with age, weight, and sex in healthy captive chimpanzee males (n = 47) and females (n = 49) to test hypotheses related to predicted differences in leptin levels with body mass, development, and sexual dimorphism. Results Leptin increased with age and weight among females, but not in males. Leptin was overall higher in females compared to males. Conclusions Sex differences in leptin were most evident during adolescence and adulthood, despite similar increases in weight in both sexes indicating that sexual maturation is a key divergence point for differential somatic investment in adiposity and leptin levels between male and female chimpanzees.