The diet of Homo naledi

Homo naledi individuals chipped their teeth remarkably often, with far more fractures than nearly all studied hominin populations (humans and closely related fossil species). This is among the first evidence to be presented on the diet and behaviour of this fascinating new addition to the human family tree and suggests they ate a substantially different diet than other South African fossil hominins. In the research described here, dental fractures, or chips as they are commonly called, were recorded on the teeth of South African fossils hominins as well as several extant primates.

The size, number and position of chips can all give insight into diet and behaviour of past populations, with each fracture created by a hard object contacting the tooth. Over 40% of H. naledi teeth are affected. To put these results into context, this is over twice the chipping rate of Australopithecus africanus, and four times that of Paranthropus robustus, two fossil hominin species often thought to commonly consume hard foods. This contrast becomes even more marked when compared to living great apes, with gorillas having around 10% of teeth chipped and chimpanzees only 5%.

The species studied with the most similar rate and pattern of chipping to H. naledi are baboons, with 25% of teeth having fractures. The chipping in baboons is likely caused by the environment in which they forage, including consuming large amounts of grit and other hard objects. The few archaeological modern human examples with similar fracture patterns also supports the conclusion that the chipping in H. naledi relates to diet and not to using teeth as tools, and is likely caused by the consumption of large amounts of grit adhering to foods. Therefore, the results of this study suggest H. naledi consumed a diet significantly different from any other fossil hominin species yet studied and they may have specialised in eating certain foods such as tubers, with grit adhering to the surface. Further research on the microscopic wear of these teeth, isotopic analysis, and studying plant remains in their dental tartar may provide further evidence for the exact cause of these dental fractures.

Research: http://onlinelibrary.wiley.com/doi/10.1002/ajpa.23250/full (DOI: 10.1002/ajpa.23250)

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