Stable Isotope Analyses and the Evolution of Human Diets

Stable isotope analysis of carbon and nitrogen has revolutionized anthropology's approach and understanding of the evolution of human diet. A baseline comparison across extant nonhuman primates reveals that they all depend on C-3 plants in forests, forest patches, and woodlands except during rare seasonal intake, in marginal regions, or where maize fields exist. Even large-bodied hominoids that could theoretically rely on hard-to-digest C-4 plants do not do so. Some Plio-Pleistocene hominins, however, apparently relied heavily on C-4 and/or CAM plants, which suggests that they relied extensively on cecal-colon microbial fermentation. Neanderthals seem less carnivorous than is often assumed when we compare their delta N-15(bone collagen) values with those of recent human populations, including recent human foragers who also fall at or near the top of their local trophic system. Finally, the introduction of maize into North America is shown to have been more sporadic and temporally variable than previously assumed.