The raw and the stolen - Cooking and the ecology of human origins

Cooking is a human universal that must have had widespread effects on the n utrition, ecology, and social relationships of the species that invented it . The location and timing of its origins are unknown, but it should have le ft strong signals in the fossil record. We suggest that such signals are de tectable at ca. 1.9 million years ago in the reduced digestive effort (e.g. , smaller teeth) and increased supply of food energy (e.g., larger female b ody mass) of early Homo erectus. The adoption of cooking required delay of the consumption of food while it was accumulated and/or brought to a proces sing area, and accumulations of food were valuable and stealable. Dominant (e.g., larger) individuals (typically male) were therefore able to scrounge from subordinate (e.g., smaller) individuals (typically female) instead of relying on their own foraging efforts. Because female fitness is limited b y access to resources (particularly energetic resources), this dynamic woul d have favored females able to minimize losses to theft. To do so, we sugge st, females formed protective relationships with male co-defenders. Males w ould have varied in their ability or willingness to engage effectively in t his relationship, so females would have competed for the best food guards, partly by extending their period of sexual attractiveness. This would have increased the numbers of matings per pregnancy, reducing the intensity of m ale intrasexual competition. Consequently, there was reduced selection for males to be relatively large. This scenario is supported by the fossil reco rd, which indicates that the relative body size of males fell only once in hominid evolution, around the time when H. erectus evolved. Therefore we su ggest that cooking was responsible for the evolution of the unusual human s ocial system in which pair bonds are embedded within multifemale, multimale communities and supported by strong mutual and frequently conflicting sexu al interest.