1Evolutionary Anthropology, Duke University, 2Center for Cognitive Neuroscience, Duke University, 3Anthropology, Hunter College, City University of New York
Saturday All day, Plaza Level
Energy expenditure in mammals varies with body size but has not been measured systematically in primates. Orangutans show remarkably low energy throughput, a strategy that may reflect a species-specific adaptation to food shortages or may represent a more general life history adaptation in the great apes. In contrast to orangutans, humans have high energy demands and maintain high activity levels, short interbirth intervals and long lifespans. To investigate energy budgets in great apes, we measured daily energy expenditure in semi-free ranging chimpanzees using the doubly-labeled water method. Energy demands vary depending on life history stage and sex, therefore total energy expenditure, TEE (kCal/day), was assessed in 8 juvenile and 9 adult chimpanzees at the Tchimpounga Chimpanzee Rehabilitation Center in Republic of Congo.
Chimpanzees used considerably less energy than similarly sized humans, and used only 31 – 35% the calories expected for a eutherian mammal of equal body mass. After controlling for body mass, male and female chimpanzees have similar TEE. Though human children devote more energy to growth in their first 24 months and have increased energy needs through the juvenile period, we found no difference in TEE between juvenile and adult chimpanzees in our sample. Chimpanzees and orangutans both show low TEE, suggesting that apes may share an ecologically conservative strategy while humans have evolved a higher TEE that allows for the maintenance of large brains, long juvenile periods and short interbirth intervals.