1School of Human Evolution and Social Change, Arizona State University, 2Department of Human Evolutionary Biology, Harvard University, 3Department of Anthropology, University of New Mexico
March 28, 2015 2:45, Grand Ballroom E/F/G
Primates have an extended period of development before they reach adulthood. One explanation for their delayed maturation is that they need a long time to learn complex foraging behaviors. Chimpanzees provide a good opportunity to test this hypothesis because they eat diverse foods, some of which require extensive handling. To explore the ontogeny of foraging behavior in chimpanzees, we used 3 years of behavioral data (2010-2013) from 28 immature and 29 adult individuals of the Kanyawara community in Kibale National Park, Uganda. We compared several measures of feeding behavior among infants, juveniles, adolescents and adults, including total daily feeding time, proportion of time spent feeding by food type, distribution of feeding time over the day, and fruit ingestion rates (number of food items eaten per minute of feeding). By late infancy chimpanzees displayed adult-like diurnal feeding peaks and ate fruit and fibrous foods at comparable proportions to adults; however, they spent a mean of only 24.5% of total time feeding, significantly less than adults (p = 0.002), whereas juvenile feeding time was equivalent to adult levels (juveniles: mean = 41.0%; adults: mean = 42.8%; p = 0.47). Furthermore, ingestion rates displayed the slowest developmental trajectory of any feeding measure, remaining below adult levels until adolescence. If extended juvenility functions to allow the learning of complex feeding behavior, these data suggest that ingestion rates may be constrained by foraging complexity. Future studies should assess whether the development of ingestion rates varies by the difficulty involved in processing different foods.
This research was supported by National Science Foundation grant BCS-1355014.