A team of Spanish paleoanthropologists has reconstructed the diet of Australopithecus anamensis, a hominid that lived in the east of the African continent more than 4 million years ago.

A. anamensis is a fossil hominid species described in 1995 and considered to be the direct ancestor of A. afarensis, known as Lucy, which lived in the same region half a million years later. The paleoecological reconstructions of the sites with A. anamensis fossil remains are quite similar to those of A. afarensis, and suggest a scene with different habitats, from open forests to thick plant formations, with herbaceous strata and gallery forests.

Traditionally, the reconstruction of the diet of A. anamensis was carried out by means of indirect evidence – specifically, studies of microstructure and enamel thickness, and the dental size and morphology.

In the new study, published in the Journal of Anthropological Sciences, the team analyzed the pattern of microstriation of the post-canine dentition, from microscopic traces that some structural components of plants and other external elements leave in the dental enamel during the chewing of food. It is, therefore, a direct analysis of the result of the diet’s interaction with the teeth.

The researchers studied the microstriation pattern of all the specimens of A. anamensis recovered up to 2003, of which only five are in a good state of preservation.

The results show that the diet of A. anamensis was very specialized and included foods typical of open environments: seeds, sedges, grasses, as well as fruits and tubers.

The results also suggest that the diet of this hominid was similar to other present day species of cercopithecoid primates, such as Papio genus (baboons) and Chlorocebus (green monkey), which live in shrubby savannah areas with a marked seasonal influence. The diet of A. anamensis was quite abrasive and rich in seeds, leaves and corms, as it is with the baboons of today. This fossil hominid must also have fed on fruit, but in smaller proportions than A. afarensis.

“The microstriation pattern of Australopithecus anamensis and Australopithecus afarensis is clearly different. This could indicate that the former consumed much harder foodstuffs, whereas the latter had a basically frugivorous diet, of a seasonal character, more similar to the direct ancestor of the two species, Ardipithecus ramidus,” said lead author Dr Ferran Estebaranz of the University of Barcelona.

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Bibliographic information: Estebaranz F et al. 2012. Buccal dental microwear analyses support greater specialization in consumption of hard foodstuffs for Australopithecus anamensis. Journal of Anthropological Sciences vol. 90, pp. 1-24; doi: 10.4436/jass.90006