The 84th Annual Meeting of the American Association of Physical Anthropologists (2015)

Weaning and hominoid life history: Serial isotopic sampling of Pan troglodytes tracks dietary change across development


1Department of Anthropology, University of Michigan, 2Department of Biological Sciences, Makerere University, Kampala, Uganda

March 26, 2015 , Archview Ballroom Add to calendar

Assessing the timing and pace of weaning in extant apes may be the key to characterizing the life histories of members of the hominoid lineage, even as far back as the early Miocene.

Stable carbon and oxygen isotope analysis of sequentially forming layers of enamel apatite allows direct testing for the pace of dietary changes taking place over developmental time. This study represents the first time an extant ape’s enamel has been sampled serially to determine the range of carbon and oxygen isotope values within an individual's dentition over the course of its dental development, from exclusive nursing, to transitional diet, to the fully adult diet.

To develop this baseline of intra-individual isotopic changes during development, we sampled enamel from P3-M3 of a female chimpanzee from Bwindi, Uganda. 4-6 samples were extracted from each tooth from the earliest forming to latest forming crown layers. δ13C values ranged from -16.7‰ to -14.0‰ and δ18O values from the same samples ranged from -0.5‰ to 1.4‰. The carbon and oxygen isotopic values of the last forming layers of enamel continued to increase suggesting this individual had not yet attained a fully adult diet by M3 crown completion. Comparisons with additional individuals and different modern primate taxa that wean earlier will permit characterizations of intra- and inter-tooth patterns of dietary change. These data will provide a basis for interpreting variable diet patterns throughout the development of an individual, including the nature and timing of weaning, and therefore overall life history patterns in fossil hominoids.