Subsistence and Stress

Early hominins were probably similar to extant baboons in having broad dietary capabilities combined with selectivity of particular items. Both taxa expanded their range of environments, with major impacts on diet. Hominin subsistence capabilities can be reconstructed from the gross anatomy of teeth and jaws. Microscopic examination of teeth can detect effects of the animal’s actual diet. Another method uses isotope ratios of elements derived from foods and preserved in the bones and teeth. Added to these approaches, baboon analogies provide more detailed suggestions as to the particular foods eaten and how they were procured. Baboon evidence suggests that protein was prioritized in all environments and that fruit was always a preferred food type. Two foods that became more important in savannas were grasses (including seeds and blades) and the underground storage organs of many plants (e.g., tubers). Baboon behavior also suggests that some hominin populations supplemented the diet with tree exudates and bark. Another possibility is consumption of soils and clays for nutritional and/or perhaps health purposes. Fluctuations in the food supply must have been a source of stress that was exacerbated with the expansion into open areas. Baboon ecology indicates that water became a limited resource that affected behavior. Heat threatened dehydration and brain damage, but baboons demonstrate simple behavioral solutions that hominins could have used.