Skull of Paranthropus boisei, formerly called Zinjanthropus boisei then Australopithecus boisei. P. boisei was an early hominid, estimated to have lived 2.6-1.2 million years ago. The skull is specialised for heavy chewing and shows the species had a small brain capacity (about 500-550 cubic cm, compared to about 1400 cubic cm for modern humans). This specimen, called OH 5 and nicknamed 'Nutcracker Man', was discovered in Olduvai Gorge, Tanzania in 1959. It is thought to be about 1.8 million years old.