1Department of Anatomy, College of Medicine, Howard University, 2Division of Anthropology, American Museum of Natural History, 3Center for the Advanced Study of Human Paleobiology, Department of Anthropology, The George Washington University, 4New York Consortium of Evolutionary Primatology (NYCEP), 5Institut Català de Paleontologia Miquel Crusafont (ICP)
April 17, 2020 , Diamond 10
Pelvic differences among hominins are suggested to reflect diet-related differences in gut size among species. This hypothesis emerges from the observation that animals with diets rich in leaves and other green plants exhibit larger guts than animals that rely on prey, and the expectation that differences in pelvic dimensions reflect accommodations for differently-sized guts. However, studies of extant primates provide little evidence supporting this hypothesis.
We test whether comparisons between pairs of similarly-sized, closely-related anthropoids reveal a link between diet and pelvic dimensions. Iliac flare, ilium width, and bi-iliac breadth were measured in 14 species (N = 234 individuals) using digital calipers. Percent time feeding on food categories were collected from the literature. Eleven comparisons were made; seven among species with different diets, and four among species with similar diet compositions. Welch’s t-tests were used to test for differences in variable means between the species in each pair. We predict that more folivorous species will have pelvic dimensions reflecting a more capacious abdominal cavity and that there will be no significant differences in pelvic dimensions in species with similar diets.
Only four comparisons support the hypothesis that more folivorous species have broader pelves than less folivorous species. The remaining comparisons yield results where: more folivorous primates have narrower pelvic dimensions, species with different diets show no differences in pelvic dimensions, or species with similar diets show differences in pelvis dimensions. These results indicate that differences in pelvic dimensions cannot reliably be used to infer differences in diet among anthropoid primates.
Funding provided by NSF (GRF; BCS 1316947), the Wenner-Gren Foundation (Dissertation Fieldwork Grant), the Agencia Estatal de Investigación (CGL2017-82654-P, AEI/FEDER EU), the Generalitat de Catalunya (CERCA Programme), and GWU.