Maturation is prolonged and variable in female chimpanzees.

Published

Journal Article

Chimpanzees are important referential models for the study of life history in hominin evolution. Age at sexual maturity and first reproduction are key life history milestones that mark the diversion of energy from growth to reproduction and are essential in comparing life history trajectories between chimpanzees and humans. Yet, accurate information on ages at these milestones in wild chimpanzees is difficult to obtain because most females transfer before breeding. Precise age at first birth is only known from a relatively small number of non-dispersing individuals. Moreover, due to small sample sizes, the degree to which age at maturation milestones varies is unknown. Here we report maturation milestones and explore sources of variance for 36 wild female chimpanzees of known age, including eight dispersing females born in Gombe National Park, Tanzania. Using Kaplan-Meier survival analysis, including censored intervals, we find an average age of 11.5 years (range 8.5-13.9) at sexual maturity and 14.9 years (range 11.1-22.1) at first birth. These values exceed previously published averages for wild chimpanzees by one or more years. Even in this larger sample, age at first birth is likely underestimated due to the disproportionate number of non-dispersing females, which, on average, give birth two years earlier than dispersing females. Model selection using Cox Proportional Hazards models shows that age at sexual maturity is delayed in females orphaned before age eight years and those born to low-ranking mothers. Age at first birth is most delayed in dispersing females and those orphaned before age eight years. These data provide improved estimates of maturation milestones in a population of wild female chimpanzees and indicate the importance of maternal factors in development.

Full Text

Duke Authors

Cited Authors

  • Walker, KK; Walker, CS; Goodall, J; Pusey, AE

Published Date

  • January 2018

Published In

Volume / Issue

  • 114 /

Start / End Page

  • 131 - 140

PubMed ID

  • 29447755

Pubmed Central ID

  • 29447755

Electronic International Standard Serial Number (EISSN)

  • 1095-8606

International Standard Serial Number (ISSN)

  • 0047-2484

Digital Object Identifier (DOI)

  • 10.1016/j.jhevol.2017.10.010

Language

  • eng