Tooth chipping can reveal the diet and bite forces of fossil hominins

Abstract

Mammalian tooth enamel is often chipped, providing clear evidence for localized contacts with large hard food objects. Here, we apply a simple fracture equation to estimate peak bite forces directly from chip size. Many fossil hominins exhibit antemortem chips on their posterior teeth, indicating their use of high bite forces. The inference that these species must have consumed large hard foods such as seeds is supported by the occurrence of similar chips among known modern-day seed predators such as orangutans and peccaries. The existence of tooth chip signatures also provides a way of identifying the consumption of rarely eaten foods that dental microwear and isotopic analysis are unlikely to detect.

Figure 1.

(a) Photograph of antemortem chips on teeth of Paranthropus robustus. (b) Schematic of enamel chip geometry. Scale bar, (a) 4 mm.

Figure 2.

(a) Plot of chip dimension h relative to tooth diameter D for a variety of living species and fossil hominins. Values of h and D are from individual chips (excluding small chips, h < 0.1 mm). Note upper limit h/D ≈ 0.30. (b) Plot of maximum chipping force P_max from equation (3.1) using averaged molar diameter D versus P_jaw from jaw mechanics. Solid line is a least squares best fit (red circle, P. boisei; red square, P. robustus; red triangle, A. afarensis; red diamond, A. africanus; inverted triangle, Homo erectus; blue circle, Homo sapiens; blue triangle, Gorilla spp.; blue square, Pongo spp.; blue diamond, Pan troglodytes; blue inverted triangle, Macaca spp.).