Ontogenetic scaling of fore- and hind limb posture in wild chacma baboons (Papio hamadryas ursinus)
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Date
2013
Authors
Patel, Biren A.
Horner, Angela M.
Thompson, Nathan E.
Barrett, Louise
Henzi, Peter
Journal Title
Journal ISSN
Volume Title
Publisher
Public Library of Science
Abstract
Large-scale interspecific studies of mammals ranging between 0.04–280 kg have shown that larger animals walk with more
extended limb joints. Within a taxon or clade, however, the relationship between body size and joint posture is less
straightforward. Factors that may affect the lack of congruence between broad and narrow phylogenetic analyses of limb
kinematics include limited sampling of (1) ranges of body size, and/or (2) numbers of individuals. Unfortunately, both issues
are inherent in laboratory-based or zoo locomotion research. In this study, we examined the relationship between body
mass and elbow and knee joint angles (our proxies of fore- and hind limb posture, respectively) in a cross-sectional
ontogenetic sample of wild chacma baboons (Papio hamadryas ursinus) habituated in the De Hoop Nature Reserve, South
Africa. Videos were obtained from 33 individuals of known age (12 to $108 months) and body mass (2–29.5 kg) during
walking trials. Results show that older, heavier baboons walk with significantly more extended knee joints but not elbow
joints. This pattern is consistent when examining only males, but not within the female sample. Heavier, older baboons also
display significantly less variation in their hind limb posture compared to lighter, young animals. Thus, within this
ontogenetic sample of a single primate species spanning an order of magnitude in body mass, hind limb posture exhibited
a postural scaling phenomenon while the forelimbs did not. These findings may further help explain 1) why younger
mammals (including baboons) tend to have relatively stronger bones than adults, and 2) why humeri appear relatively
weaker than femora (in at least baboons). Finally, this study demonstrates how field-acquired kinematics can help answer
fundamental biomechanical questions usually addressed only in animal gait laboratories.
Description
Sherpa Romeo green journal: open access
Keywords
Wild chacma baboons , Papio hamadryas ursinus , Hind limb posture , Forelimb posture , Joint posture , Elbow joint angles , Knee joint angles , Body mass , Biomechanics , Ontogenetic sample
Citation
Patel, B. A., Horner, A. M., Thompson, N. E., Barrett, L., & Henzi, S. P. (2013). Ontogenetic scaling of fore- and hind limb posture in wild chacma baboons (Papio hamadryas ursinus). PLoS ONE, 8(7): e71020. doi:10.1371/journal.pone.0071020