Testing Hypotheses About the Relationship Between Diet and Torso Morphology in Extant Primates: Implications for Human Evolution
Open AccessTorso differences between Australopithecus and Homo are often claimed to reflect a reduction in gut size following an increase in diet quality in the latter genus. This hypothesis emerges from the fact that animals that primarily eat green plants exhibit larger guts than animals that rely on prey, and the assumption that torso form reflects accommodations for differently sized guts. However, recent studies show that other factors might influence primate torso morphology (e.g., body mass, locomotion), and the existence and nature of any relationships between the torso and diet have not been demonstrated in living primates. This dissertation uses phylogenetic generalized least squares (PGLS) regressions and other analyses to test hypotheses relating diet to anthropoid primate torso morphology. Linear measurements and 3D torso volume were collected across a broad sample of primates and integrated with data on gut size, feeding observations, locomotion, and body size from the literature. Chapter 1 introduces the background and research objectives. Chapter 2 tests hypotheses that have been laid forth in the paleoanthropological literature. I present the results of two analyses that use PGLS regressions and another that utilizes discriminant function analysis to test how torso form is related to diet and locomotion. Chapter 3 provides more narrow comparisons among a subsample of anthropoid species. Chapter 4 identifies if torso volume, calculated from the convex hulls of articulated torsos, is related to diet. Chapter 5 presents the conclusions of the dissertation and the significance of the results for describing and analyzing fossil hominin torso remains.The analyses presented in this dissertation demonstrate that there is no consistent relationship between the extant primate torso and observed diets and gut sizes. Across the entire sample, torso features—considered both individually and together—are more closely related to body size and locomotion than to diet. Narrow comparisons among similarly-sized, closely-related species reveal that there is no reliable pattern in how torso dimensions vary among species with different or similar diets. Variation in torso volume is also driven by body size and phylogenetic relatedness and is not related to diet or gut size. Altogether, this research suggests there is no basis to support the practice of inferring diet from fossil hominin torso remains.
- All rights reserved
Notice to Authors
If you are the author of this work and you have any questions about the information on this page, please use the Contact form to get in touch with us.