A comparison of antemortem tooth loss in human hunter-gatherers and non-human catarrhines: implications for the identification of behavioral evolution in the human fossil record.

Middle and Late Pleistocene fossil hominin specimens with severe antemortem tooth loss are often regarded as evidence for the precocious evolution of human-like behaviors, such as conspecific care or cooking, in ancient hominin species. The goal of this project was to ask whether the theoretical association between antemortem tooth loss and uniquely human behaviors is supported empirically in a large skeletal sample of human hunter-gatherers, chimpanzees, orangutans, and baboons. Binomial regression modeling in a Bayesian framework allows for the investigation of the effects of tooth class, genus, age, and sex on the likelihood of tooth loss. The results strongly suggest that modern humans experience more antemortem tooth loss than non-human primates and identify age in years as an important predictor. Once age is accounted for, the difference between the humans and the closest non-human genus (chimpanzees) is less pronounced; humans are still more likely on average to experience antemortem tooth loss though 95% uncertainty envelopes around the average prediction for each genus show some overlap. These analyses support theoretical links between antemortem tooth loss and modern human characteristics; humans' significantly longer life history and a positive correlation between age and antemortem tooth loss explain, in part, the reason why humans are more likely to experience tooth loss than non-human primates, but the results do not exclude behavioral differences as a contributing factor.