Abstract # 4429 Event # 140:

Scheduled for Friday, June 21, 2013 05:00 PM-05:15 PM: Session 19 (Auditorium) Oral Presentation


M. N. Muchlinski and H. Vollrath
University of Kentucky, Department of Anatomy and Neurobiology, 800 Rose Street, MN 210, Lexington, Kentucky 40536, USA
     Despite major differences in morphology and ecology, mammalian species have broadly similar metabolic requirements relative to body size. This suggests that the total energy available for meeting the metabolic needs of the various somatic organs and tissues is constrained. Thus, available energy is allocated differentially depending upon the metabolic needs of each species. This is the basis of the Expensive Tissue Hypothesis, which proposes an explanation for how humans are able to maintain large, energy-expensive brains while having resting metabolic rates that are not substantially different from other mammals. Muscle tissue, despite relatively low costs when at rest, requires a substantial portion of overall daily metabolic requirements. We hypothesize that muscle mass will be lower in mammals with large brains. To test this hypothesis, we obtained total muscle mass values from dissection and the literature for 23 primate and 56 non-primate mammals. We measured endocranial volume (ECV) for each species. We compared primates and non-primate mammals in relative muscularity, and examined how muscle mass covaries with ECV. Results indicate that primates are hypomuscular when compared to non-primate mammals (p<0.001). We also documented a negative correlation between relative muscle mass and relative ECV (p<0.05). This suggests that mammals may 'save' energy by reducing muscle mass, which can then be allocated to the brain and other tissues.