Chapter Review
Finding out what early hominins actually did and how they acted are tricky tasks, particularly since it is difficult to imagine what the landscape might have been like hundreds of thousands—or even millions—of years ago. Researchers can use inferences drawn from animal studies, especially those of the African great apes (i.e., gorillas, chimpanzees, and bonobos), although none of the ape models is expected to provide an exact replica of hominin behavior. Comparison using contemporary hunter-gatherers draws on human behavioral variation through the study of different cultures. Existing societies are fully modern people and therefore not exact replicas of the hominin lifestyle, but many insights have arisen through the study of human foraging societies. The fact that there appear to be many commonalities between culturally different foraging societies suggests that ecological constraints may provoke similar responses from different people.
Human foragers typically combine extractive foraging (acquiring food that must be processed in some way before it can be eaten, such as nuts with hard shells and tubers) with hunting, skills that require years of practice to hone. In contrast, when chimpanzees forage, they rely almost exclusively on collected foods, those that may simply be picked and eaten. Hominins may have evolved larger brains and a longer period of juvenile development to adapt to the rigors of a complex foraging lifestyle.
Meat has been a part of the hominin diet for millions of years, but it is a precious commodity for modern foraging groups, providing a bonanza of calories and proteins that are otherwise difficult to acquire. Hunting parties, more often than not, return empty-handed. Bearing that in mind, there are two factors that make a system of food sharing desirable, if not absolutely necessary, for relying on meat in the diet to be feasible: a high payoff for success but a low individual success rate. These conditions suggest that a network of food sharing would greatly benefit all participating parties by providing a buffer against starvation (or malnutrition) due to individual irregularities in success.
Much of the archaeological evidence also points to a shift in dietary composition, although direct evidence of meat eating is rarely found so meat eating has to be inferred. One source is through the interpretation of the presence and quantity of different skeletal elements found on living floors (supposed places of hominin occupation). High densities of bones found in association with stone tools have led researchers to believe that processing and consumption of carcasses took place at these sites. However, accumulations of bones and stone tools, while intriguing as evidence of hominin meat eating, could also be the result of unrelated processes. Careful examination of the surrounding matrix is required.
Sites from Olduvai Gorge examined in this manner suggest that site accumulation was not a by-product of river deposition. A number of the bones accumulated in the Olduvai Gorge sites exhibit evidence of cut marks made by stone tools. Although it may be difficult to distinguish between tool-derived cut marks and other possible agents of bone modification (for example, carnivore tooth marks) with the naked eye, examination under high magnification shows a clear distinction between the two.
Additional interpretations can also be arrived at concerning the timing and sequence of resource acquisition by examining whether carnivore teeth or hominin tool marks came first. Were hominins hunters or merely scavengers of the remains of prey felled by larger carnivores? The available evidence suggests that early hominins engaged in both activities, although the evidence for hunting and primary access to meat resources increases in later species. The effects of this behavioral change on the development and evolution of hominin social organization have been profound, particularly in the realm of cooperation within social groups.