The Hadza Carcass Transport Debate Revisited and its Archaeological Implications

Abstract The paper is a re-analysis of carcass transport data reported by two research groups (Bunn, Bartram & Kroll; O’Connell, Hawkes & Blurton Jones) monitoring the foraging activities of Hadza hunter–gatherers (northern Tanzania). The two teams offer different conclusions about the patterning, explanation and archaeological implications of Hadza field processing and transport decisions, yet the overall similarity between their data sets suggests that the conflicting conclusions have more to do with interpretive differences than with inherently different samples. At issue is whether or not the Hadza provide support for a concept known as the ‘‘schlepp effect’’, which has been used to identify transported bone assemblages in the early archaeological record on the basis of high limb bone representation relative to axial parts. The re-analysis mostly contradicts the ‘‘high limb schlepp effect’’ (my term), and three main aspects of Hadza carcass transport are noteworthy. First, animals up to zebra size (i.e. c . 750 lb) are frequently transported completely and, even when some bones are discarded, the edible tissues associated with them are almost always consumed and/or transported. This is possible because the Hadza are able to spend relatively unlimited amounts of time at kill/butchery locations (i.e. predation risk is insignificant), which allows for extensive processing, food consumption and the summoning of many carcass carriers. Second, except for ribs, post-cranial axials (not limbs) are the most frequently transported elements. Finally, ribs and limb bones are often discarded at kill/butchery locations and their associated edible tissues are either eaten on the spot or transported to camps. In short, the Hadza try to transport as much food as possible, while reducing transport weight by discarding easily processed elements such as ribs and long bones. Interestingly, one cannot simply reflect these results back in time and expect that transported bone assemblages in the early archaeological record will also be dominated by post-cranial axials, with fewer long bones, and so on. This is because significant biological and ecological differences may exist between the modern Hadza and Early Pleistocene hominids. Foremost among these differences is predation risk from large carnivores at fresh carcasses, which would significantly alter the interplay between processing costs, transport costs and food benefit of ungulate carcasses. Modelling of these variables shows that increased predation risk limits time available at kill/butchery locations, which in turn limits the amount of meat-stripping, bone discard, food consumption and the number of available carriers. Under these conditions, early hominid foragers would be expected to discard or transport bones and associated edible tissues together, and two broadly different transport strategies—a weight-minimizing and a food-maximizing strategy—are theoretically possible based on the number of carcass carriers, carcass size and distance of transport. A weight-minimizing strategy closely resembles the ‘‘high limb schlepp effect’’, in fact, but the important point is that a ‘‘one size fits all’’ model for recognizing a transported bone assemblage is simply not realistic given the number of inter-related variables. The Hadza study also suggests that skeletal part data from large bone assemblages reflect diverse foraging returns, rather than a unimodal pattern of hominid carcass exploitation. Accordingly, archaeologists should be more cautious about reconstructing ‘‘typical’’ patterns of hominid carnivory and carcass transport from dense bone accumulations. Finally, some methodological suggestions are offered to enhance the explanatory power of skeletal part data by integrating them with surface modification data.