Abstract # 210:

Scheduled for Monday, August 28, 2017 12:45 PM-01:00 PM: (Grand Ballroom) Oral Presentation


MUSCULOSKELETAL GROWTH IN WILD CHIMPANZEES WITH IMPLICATIONS FOR SOCIAL BEHAVIOR

Z. Machanda1, N. Brazeau2, E. Castillo3, E. Otarola-Castillo4, H. Pontzer5, M. Emery Thompson6, M. Muller7 and R. Wrangham3
15 The Green, 302 Eaton Hall, Dept. of Anthropology, Tufts, Tufts University, Medford, Massachusetts 02155, USA, 2University of North Carolina Medical School, 3Harvard University, 4Purdue University, 5Hunter College, 6University of New Mexico, 7University of New Mexico
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     Developmental data from our closest living relatives are of particular interest for identifying which aspects of human life history are derived. To date, most of our knowledge of chimpanzee growth comes from data on captive populations despite indications that these individuals develop faster than their wild counterparts. In this study, we examine patterns of growth among wild chimpanzees of the Kanyawara community in Uganda. From 2012-2014, body size estimates were acquired for over 50 individuals using parallel laser photogrammetry to calculate trunk lengths (as measures of linear growth) and cross-sectional trunk area (as an approximation of body weight). Two important patterns of chimpanzee growth emerge from this study. First, compared to captive populations, wild chimpanzees exhibit a delayed adolescent growth spurt as well as an extended adolescent growth period. Second, male body size measures indicate that 10-year olds maintain body lengths within the range of those exhibited by adult males, but their body areas fall below the adult male range and only reach adult sizes between the ages of 15-17. This indicates that skeletal growth is likely completed before the addition of muscle mass for these males. The adult skeleton size is achieved during a period of social transition away from adult mothers while the increase in muscle mass is occurring after males have been socially integrated into the adult male hierarchy.