Born to chew

Olduvai Hominid 5 (OH 5) is easily the most famous of the early human fossils found at Olduvai Gorge. It is a nearly complete cranium of an adult male P. boisei. Originally named Zinjanthropus boisei, its classification was changed to Australopithecus boisei and later Paranthropus boisei, placing it in the same genus as the southern African species. The fossil is still referred to today as "Zinj", in reference to its original name.

The South African species Paranthropus robustus provided the original standard for the robust cranial form: a large sagittal crest on the top of the skull, a flat face formed by large zygomatic arches positioned far forward and megadont cheek teeth. But with the discovery of "Zinj" in eastern Africa, a new level of robusticity was defined, sometimes called "hyper-robust". Notice the wide zygomatic arches which project forward of the nasal opening and form the dished-shape face typical of Paranthropus boisei. The outward flaring of these bony arches from the side of the head provided space for large temporalis muscles. These were the huge chewing muscles that passed from the lower jaw to the large sagittal crest atop the skull. In some cases, the megadont cheek teeth of Paranthropus boisei were four times the size of our own.

Image of OH 5 "Zinj" skull, 3/4 view
OH 5
Exhibit item
Nutcracker Man
Olduvai Gorge, Tanzania
Date of discovery: 
Discovered by: 
Mary Leakey
About 1.8 million years old
Paranthropus boisei
Born to chew This species was nicknamed for its big teeth and strong chewing muscles, which attached to the large crest on the skull. Those features show that <italic>Paranthropus boisei</italic> ate tough foods like roots and nuts. But microscopic analysis of wear on the teeth of other <italic>P. boisei</italic> individuals reveals that it also often ate soft foods like fruit.