This vegetarian apeman had a big, flat face with a massive jaw. It lived at a time when forests were vanishing from East Africa, creating a shortage of food such as soft fruit.

Paranthropus boisei coped with the shortage by evolving a massive jaw and huge teeth to chomp tough-to-chew foods such as nuts, roots, seeds and tubers.

These hard, gritty foods were more abundant in the open woodland and grasslands that boisei called home.

Paranthropus boisei may have lived in groups organized in harems, in which one male mated with many females. Males were easy to spot amongst a harem of females; they were much more muscular with much bigger faces.

Lantern jaws

Paranthropus boisei developed an enormous jaw with massive chewing muscles and huge back teeth to help him grind down these tough plant foods. By becoming a highly specialised vegetarian, boisei ensured a comfortable life for itself.

The ratios of different types of carbon atoms, or isotopes, in fossils can tell us lots about what a fossil creature ate because different foods have different carbon isotope signatures. Dr Julia Lee-Thorp of the University of Cape Town in South Africa has found that isotopes in boisei's southern African relative, Paranthropus robustus, show that it ate a relatively high proportion of foods with a Carbon-4 (C4) signature.


On 24 November 1974 in the Afar region of Ethiopia, anthropologists Donald. Johanson and Tom Gray made one of the most famous fossil discoveries ever.

While out fossil hunting in sandy ravines near the River Awash, they discovered a 40% complete skeleton dating to 3.2 million years ago. They named the find 'Lucy'. Lucy's species, Australopithecus afarensis, have small canine teeth compared with apes. This suggests males may have been cooperating.

Examinations of Lucy's knee joint and pelvis demonstrate that she walked upright. And footprints left in volcanic tuff at Laetoli in Tanzania by afarensis suggest it walked with a human-like stride.