About 2.5 million years ago southern Africa was dying. Although some trees remained near watercourses, the forest largely turned into grass land, and animals moved, adapted, or died out. For robustus, shown here defending its territory, this meant living on tough foods like roots, tubers and seeds instead of softer foods like fruits.

The Hominids developed large jaws and molars to handle this fare; males had such huge jaws that their muscles were attached to bony crest on top of their skulls. Females did not have these crests, and their jaws and teeth were as much a as third smaller than males’ a greater difference than we had previously seen. These finds especially the female skulls give us a much better picture of the species. We even found some sharpened bone points most likely from bones used as digging tools. We believe robustus used bones tools and probably used this for particular ones.