The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Preliminary Investigation of Forelimb Use among Cercopithecoid Primates in Côte d’Ivoire’s Taï Forest


1Department of Anthropology, The Ohio State University, 2Departement Biodiversite et Securite Alimentaire, Centre Suisse de Recherques Scientifiques, 3Department of Anthropology, University of Florida

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The Cercocebus-Mandrillus clade is characterized by skeletal adaptations associated with collecting and processing obdurate foods from the forest floor. Compared to other African papionins, drills, mandrills and terrestrial mangabeys exhibit greater radial and ulnar interosseous ridging, more proximally-extending supinator crests, and more pronounced brachialis flanges indicative of frequent, powerful manual foraging. Although these osteological features are readily apparent, whether they reflect significant differences in forelimb mechanics has not been examined quantitatively. Here we present preliminary field data testing a null hypothesis of no difference in forelimb activities between sooty mangabeys (Cercocebus atys) and two sympatric cercopithecids (Procolobus badius, Colobus guereza) inhabiting the Taï Forest.

We used focal sampling to quantify use rates of five forelimb movements employed during foraging: “raking” through leaves while pronating and supinating the forearm, manipulating held objects, and introducing objects to the mouth from below (B), in front (F), or above the torso (A). Results indicate that sooty mangabey foraging involves over twice as many forelimb movements as colobine foraging (p = 0.018, F=4.07). Neither colobine species “raked,” which comprised 52% of C. atys forelimb activity. Both colobines performed F more frequently than sooty mangabeys (p < 0.01, F = 84.62), while the latter performed B more frequently than colobines (p < 0.01, F = 10.96). There was no significant interspecific difference in A or object manipulation. These pronounced behavioral differences strongly support the hypothesis that the forelimb of Cercocebus-Mandrillus clade members is adapted to vigorous manual foraging activities.

This research was supported by NSFBCS 0921770.

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