Almost human: the fossils of early Homo

Abstract

The earliest fossils of our genus date to 2.5 ‐ 2.0 million years ago (Ma) in Africa, but are so rare and anatomically limited as to reveal little about the nature of its origin beyond an association with a fluctuating trend towards more open, wetter environments. There are various claimants for Homo ancestry, but a taxon resembling Australopithecus africanus provides the best candidate for this root node. Between 2.0 ‐ 1.5 Ma, the fossil record is significantly better. Specimens are attributed to three taxa – Homo habilis, H. rudolfensis and H. erectus. Appreciation of the locomotor anatomy of H. habilis and H. rudolfensis is hampered by the lack of associated, relatively complete specimens. This anatomy is better known for H. erectus. Homo habilis retains features suggestive of frequent arboreality. Homo erectus was an obligate terrestrial biped; some features may have been associated with long distance running ‐ a valuable attribute for hunting/scavenging – but others seem to be inconsistent with running or throwing behaviors. Homo erectus was more similar to chimpanzees than to H. sapiens in the timing of life history parameters. Early Homo molars tend to be narrower and with more occlusal relief than those of earlier hominins; occlusal microwear suggests a diverse diet that included tough foods. The manufacture and use of stone tools in foraging appear to have been early attributes of our genus.