In paleoanthropology the group of hominids known as the "robust" australopithecines has emerged as one of the most interesting. Through them we have the opportunity to examine the origin, natural history, and ultimate extinction of not just a single species, but of an entire branch in the hominid fossil record. It is generally agreed that the human lineage can be traced back to this group of comparatively small-brained, large-toothed creatures...