Sexual dimorphism in a sample of semi-commensal chacma baboons (Papio ursinus) from South Africa
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Date
2022-05
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The Ohio State University
Abstract
The determinants of sexual dimorphism continue to be investigated. Here we investigate sexual dimorphism in a skeletal sample of 29 (21 males, 8 females) chacma baboons (Papio ursinus) from South Africa. The sample comprises individuals living in proximity to humans that were euthanized due to raiding and other issues related to baboon-human conflict. Body weights of several males exceed the largest on record. We use dental measurements to test the hypotheses that (a) body weight and canine size are correlated in males, (b) Both male and whole sample body weights and femoral head diameter sizes will correlate more strongly with canine than with second molar crown size, and (c) this sample exhibits greater sexual dimorphism relative to museum collections of the same species. These associations are expected for at least 2 reasons: (1) higher testosterone levels during development, often associated with aggression and increased muscle mass, increase both body and canine sizes; and (2) males with larger canines are better able to access human-derived foods and increase their body weights. While the canine dimensions of our sample fell within the range of museum collections of P. ursinus and other baboon taxa, sexual dimorphism in canine mesio-distal and crown height dimensions exceeded that of comparative published samples. Correlations between male body weight and tooth size were in most cases greater for maxillary canines than for second molars or mandibular canines. Our results support an association between maxillary canine size, body weight, and femoral head diameter size related to baboon-human conflict.
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Department of Anthropology's Best Undergraduate Writing Award for 2022