Molar microwear textures and the diets of Australopithecus anamensis and Au

Department of Anthropology, University of Arkansas, Old Main 330, Fayetteville, AR 72701, USA.
Philosophical Transactions of The Royal Society B Biological Sciences (Impact Factor: 7.06). 10/2010; 365(1556):3345-54. DOI: 10.1098/rstb.2010.0033
Source: PubMed


Many researchers have suggested that Australopithecus anamensis and Australopithecus afarensis were among the earliest hominins to have diets that included hard, brittle items. Here we examine dental microwear textures of these hominins for evidence of this. The molars of three Au. anamensis and 19 Au. afarensis specimens examined preserve unobscured antemortem microwear. Microwear textures of these individuals closely resemble those of Paranthropus boisei, having lower complexity values than Australopithecus africanus and especially Paranthropus robustus. The microwear texture complexity values for Au. anamensis and Au. afarensis are similar to those of the grass-eating Theropithecus gelada and folivorous Alouatta palliata and Trachypithecus cristatus. This implies that these Au. anamensis and Au. afarensis individuals did not have diets dominated by hard, brittle foods shortly before their deaths. On the other hand, microwear texture anisotropy values for these taxa are lower on average than those of Theropithecus, Alouatta or Trachypithecus. This suggests that the fossil taxa did not have diets dominated by tough foods either, or if they did that directions of tooth-tooth movement were less constrained than in higher cusped and sharper crested extant primate grass eaters and folivores.

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    • "Therefore, at first glance, there appears to be discrepancy between the microwear and the type of diet consumed by the youngest children, as textual accounts indicate that a soft and limited range of foods, such as pap or panda (Orme, 2003:71) would have been consumed. However, a high epLsar can also be indicator of jaw movements during chewing (Ungar et al., 2010). On average, the one to year olds had the most anisotropic texture surfaces compared to all other childhood groups. "
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    • "Microwear texture attributes were produced using the scale-sensitive fractal analysis software packages ToothFrax and SFrax (SurFract Corp) [Scott et al., 2005; Ungar et al., 2010]. Variables measured include complexity (Asfc or area-scale fractal complexity), anisotropy (epLsar or exact proportion length-scale anisotropy of relief), textural fill volume (Tfv), scale of maximum complexity (Smc), and heterogeneity of complexity (HAsfc or heterogeneity of area-scale fractal complexity). "
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    • "africanus (Scott et al., 2005) and Au. afarensis (Ungar et al., 2010) shows a highly variable diet with last meals mostly comprising either soft or tough materials. Animal tissues may be quite tough and require significant masticatory effort (Wrangham and Conklin-Brittain, 2003), but this is not problematic if only small amounts of meat were eaten (Hardus et al., 2012). "
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