International Journal of Primatology

, Volume 29, Issue 6, pp 1401-1420

First online:

Open Access This content is freely available online to anyone, anywhere at any time.

Role of Nonbehavioral Factors in Adjusting Long Bone Diaphyseal Structure in Free-ranging Pan troglodytes

  • K. J. CarlsonAffiliated withDepartment of Anatomy, New York College of Osteopathic Medicine Email author 
  • , D. R. SumnerAffiliated withDepartment of Anatomy and Cell Biology, Rush Medical College
  • , M. E. MorbeckAffiliated withDepartments of Anthropology and Cell Biology and Anatomy, University of Arizona
  • , T. NishidaAffiliated withMahale Mountains Chimpanzee Research Project, Graduate School of Science, Kyoto University
  • , A. YamanakaAffiliated withDepartment of Oral Anatomy, Kagoshima University Dental School
  • , C. BoeschAffiliated withMax-Planck Institute for Evolutionary Anthropology


Limb bones deform during locomotion and can resist the deformations by adjusting their shapes. For example, a tubular-shaped diaphysis best resists variably-oriented deformations. As behavioral profiles change during adulthood, patterns of bone deformation may exhibit age trends. Habitat characteristics, e.g., annual rainfall, tree density, and elevation changes, may influence bone deformations by eliciting individual components of behavioral repertoires and suppressing others, or by influencing movements during particular components. Habituated chimpanzee communities provide a unique opportunity to examine these factors because of the availability of morphological data and behavioral observations from known-age individuals inhabiting natural habitats. We evaluated adult femora and humeri of 18 female and 10 male free-ranging chimpanzees (Pan troglodytes) from communities in Gombe (Tanzania), Mahale Mountains (Tanzania), and Taï Forest (Côte d’Ivoire) National Parks. We compare cross sections at several locations (35%, 50%, 65% diaphyseal lengths). Community comparisons highlight different diaphyseal shapes of Taï females relative to Mahale and Gombe females, particularly in humeral diaphyses. Age trends in diaphyseal shapes are consistent with reduced activity levels in general, not only reduced arboreal activity. Age-related bone loss is apparent among community females, but is less striking among males. Community trends in diaphyseal shape are qualitatively consistent with ranked annual rainfall at localities, tree density, and elevation change or ruggedness of terrain. Habitat characteristics may contribute to variation in diaphyseal shape among chimpanzee communities, much like among modern human groups, but verification awaits further rigorous experimental and comparative analyses.


aging Gombe locomotor behavior Mahale Pan troglodytes Taï