It is not much what is eaten but what is done to it beforehand.
Chapter 4 left off on evidence of dietary divergence between Paranthropus and early Homo, evidence that lends support to Robinson's Dietary Hypothesis. The present chapter considers how dental evidence contributes to our understanding of dietary change within the genus Homo, prior to the evolution of Neanderthals and anatomically modern humans (AMHS). During this period of human evolution, archaeological evidence becomes a crucial source of information for dietary reconstruction. Faunal remains with evidence of human alteration (e.g., butchery), stone tools and eventually evidence of controlled use of fire supply crucial pieces of the dietary puzzle in the Homo lineage. But teeth, too, yield important clues. This chapter focuses on those clues within their archaeological context.
In addition, this chapter reviews evidence and explores arguments for the possibility that changes in culture – the use of tools and fire – had an effect on dental evolution in Homo habilis, Homo erectus, and Homo heidelbergensis. While a major reduction in the size of the canine apparently occurred at or near the base of the hominin clade (Chapter 3), posterior teeth did not reduce until much later, arguably not until the appearance of Homo erectus (251, 324). There were also changes in anterior teeth. Relative to estimated body size, incisor teeth are larger in Homo habilis than they are in any australopith, but then decrease in size with Homo erectus (325).
The big question is why posterior teeth (and later anterior teeth) reduced in size in the first place. Anthropological legend C. Loring Brace and colleagues found that major reductions in tooth size during the Pleistocene occurred relatively recently, during the last 200,000–300,000 years (commentary in Current Anthropology on Wrangham and colleagues’ cooking hypothesis ). Brace argued that the degree of dental reduction in different regions of the world is proportional to the length of time people have been cooking in these regions (326). Cooking would have had the effect of softening food and thus relaxing the selection pressure on maintaining large teeth to process hard and/or tough foods.