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


Musculoskeletal growth patterns in wild chimpanzees (Pan troglodytes)

ZARIN MACHANDA1, NICHOLAS F. BRAZEAU2, ERIC CASTILLO1, ERIK OTÁROLA-CASTILLO1, HERMAN PONTZER3, MELISSA EMERY THOMPSON4, MARTIN MULLER4 and RICHARD W. WRANGHAM1.

1Department of Human Evolutionary Biology, Harvard University, 2Medical School, University of North Carolina, 3Department of Anthropology, Hunter College, 4Department of Anthropology, University of New Mexico

March 28, 2015 3:15, Grand Ballroom E/F/G Add to calendar

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. These results call for a re-evaluation of using captive chimpanzee growth estimates as a model for the ancestral hominin growth pattern and suggest that wild chimpanzee and human growth patterns are more similar than previously expected. They also demonstrate an important difference between skeletal and muscular growth that needs to be considered in studies of human life history evolution.

Funding provided by Harvard University (NFB and ZPM), American Society of Primatologist Small Grant (NFB), the Wenner Gren Hunt Fellowship (ZPM) and the National Science Foundation 1355014 (MNM, RWW, MET)