%0 Journal Article
%A Hanegraef, Hester
%A Spoor, Fred
%+ Department of Human Origins, Max Planck Institute for Evolutionary Anthropology, Max Planck Society
%T Maxillary morphology of chimpanzees: Captive versus wild environments (advance online) : 
%G eng
%U https://hdl.handle.net/21.11116/0000-000E-61E9-E
%R 10.1111/joa.14016
%7 2024-01-31
%D 2024
%8 31.01.2024
%* Review method: peer-reviewed
%X Morphological studies typically avoid using osteological samples that derive from cap-<br>tive animals because it is assumed that their morphology is not representative of wild<br>populations. Rearing environments indeed differ between wild and captive individu -<br>als. For example, mechanical properties of the diets provided to captive animals can<br>be drastically different from the food present in their natural habitats, which could<br>impact cranial morphology and dental health. Here, we examine morphological differ-<br>ences in the maxillae of wild versus captive chimpanzees (Pan troglodytes) given the<br>prominence of this species in comparative samples used in human evolution research<br>and the key role of the maxilla in such studies. Size and shape were analysed using<br>three-dimensional geometric morphometric methods based on computed tomogra-<br>phy scans of 94 wild and 30 captive specimens. Captive individuals have on average<br>larger and more asymmetrical maxillae than wild chimpanzees, and significant differ-<br>ences are present in their maxillary shapes. A large proportion of these shape differ-<br>ences are attributable to static allometry, but wild and captive specimens still differ<br>significantly from each other after allometric size adjustment of the shape data. Levels<br>of shape variation are higher in the captive group, while the degree of size variation is<br>likely similar in our two samples. Results are discussed in the context of ontogenetic<br>growth trajectories, changes in dietary texture, an altered social environment, and<br>generational differences. Additionally, sample simulations show that size and shape<br>differences between chimpanzees and bonobos (Pan paniscus) are exaggerated when<br>part of the wild sample is replaced with captive chimpanzees. Overall, this study con-<br>firms that maxillae of captive chimpanzees should not be included in morphological or<br>taxonomic analyses when the objective is to characterise the species.<br>
%K captivity, diet, geometric morphometrics, growth, maxilla, sexual dimorphism, variation
%J Journal of Anatomy
%@ 0021-87821469-7580