The 84th Annual Meeting of the American Association of Physical Anthropologists (2015)

Differences in life history strategies in bonobos and chimpanzees: evidence from age-related changes in urinary testosterone levels


1Department of Primatology, Max Planck Institute for Evolutionary Anthropology, 2Department of Anthropology, Indiana University Bloomington, 3Centre for Research and Conservation, Royal Zoological Society of Antwerp

March 28, 2015 4:15, Grand Ballroom E/F/G Add to calendar

Developmental changes such as reproductive maturation are induced by a number of endocrine processes. For the onset of puberty in human and non-human primates, age-related changes in testosterone excretion are an indirect marker. While endocrinological changes during puberty are well investigated for male chimpanzees, less is known about puberty in female chimpanzees and bonobos. We investigated patterns of urinary testosterone levels in both sexes using urine samples from bonobos and chimpanzees to determine the onset of puberty. We found that older individuals of both sexes had significantly higher urinary testosterone levels than younger individuals, indicating that bonobos and chimpanzees experience juvenile pause, thereby following the general mammalian pattern. In males of both species, urinary testosterone levels increased around eight years of age and were comparable whereas in female bonobos, the increase occurred about three years earlier than in female chimpanzees. The study shows that urinary testosterone levels are a useful marker to detect the onset of puberty in both sexes in chimpanzees and bonobos. In males, age-related changes in urinary testosterone appear to be independent of species differences in aggression and mate competition seen in adolescents and adults. The finding that urinary testosterone levels rise earlier in female bonobos than in chimpanzees corresponds with an earlier time of first dispersal and suggests female bonobos may reach puberty at a younger age than female chimpanzees.