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Dental microwear texture analysis shows within-species diet variability in fossil hominins

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Abstract

Reconstructing the diets of extinct hominins is essential to understanding the paleobiology and evolutionary history of our lineage. Dental microwear, the study of microscopic tooth-wear resulting from use1,2,3,4, provides direct evidence of what an individual ate in the past. Unfortunately, established methods5,6,7,8,9,10 of studying microwear are plagued with low repeatability and high observer error11. Here we apply an objective, repeatable approach for studying three-dimensional microwear surface texture to extinct South African hominins. Scanning confocal microscopy12,13 together with scale-sensitive fractal analysis14,15,16,17,18,19 are used to characterize the complexity and anisotropy of microwear. Results for living primates show that this approach can distinguish among diets characterized by different fracture properties. When applied to hominins20, microwear texture analysis indicates that Australopithecus africanus microwear is more anisotropic, but also more variable in anisotropy than Paranthropus robustus. This latter species has more complex microwear textures, but is also more variable in complexity than A. africanus. This suggests that A. africanus ate more tough foods and P. robustus consumed more hard and brittle items, but that both had variable and overlapping diets.

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Acknowledgements

We are grateful to the curators at the US National Museum of Natural History, the Transvaal Museum and the University of the Witwatersrand for permission to study specimens in their care, and thank A. Pérez-Pérez for his help preparing the hominin replicas. This project was funded by the US National Science Foundation.

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Competing interests

C.A.B. owns and operates Surfract (http://www.surfract.com), which developed and markets Kfrax. To the extent that someone might decide to purchase Kfrax as a result of this publication, he could benefit financially. Some features used in the analysis are in beta and development and are not commercially available.

Correspondence to Peter S. Ungar.

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Further reading

Figure 1: Scale-sensitive fractal analysis.
Figure 2: Microwear texture analyses.
Figure 3: Anisotropy and complexity.

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