Microscope reveals ‘Nutcracker Man’ may not live up to his name

David L. Shenkenberg

Half a century ago, scientists uncovered the 1.2- to 2.3-million-year-old bones of Paranthropus boisei in eastern Africa. It had the flattest cheek teeth and thickest enamel of any known human ancestor. The size and shape of the teeth, jaws and cranium led the scientists to conclude that P. boisei ate hard and brittle foods such as nuts, seeds, roots and tubers. Thus, P. boisei became known popularly as the “Nutcracker Man.”

This illustration shows what Paranthropus boisei might have looked like some 1.2 to 2.3 million years ago. Courtesy of the National Science Foundation.

However, the teeth show what it could have eaten, not necessarily what it did eat, said Peter S. Ungar of the University of Arkansas in Fayetteville. He and Frederick E. Grine of Stony Brook University in New York and Mark F. Teaford of Johns Hopkins University in Baltimore studied the teeth of the early human ancestor.

They made dental impressions and microscopically examined them for wear marks using the Sensofar PLμ confocal imaging profiler from Solarius Development Inc. of Newton, Mass. They used special software to analyze the complexity of the scratches and pits in the teeth.

P. boisei had the flattest cheek teeth and thickest enamel of any known human ancestor.

As reported in the April 2008 issue of the online journal Public Library of Science One, the teeth exhibited only light wear, which indicated that P. boisei ate mostly soft foods such as fruits rather than hard and brittle foods.

The researchers believe that, although P. boisei had evolved to be able to eat nuts and seeds, it ate these only when its preferred foods were scarce.

The researchers examined the teeth for wear marks using confocal white-light profilometry. The teeth showed only light wear, which indicates that the so-called “Nutcracker Man” actually preferred soft foods such as fruits.

The size and shape of the teeth, cranium and jaws indicate that P. boisei could have eaten hard and brittle foods.