The skull of Paranthropus boisei, known for decades as Nutcracker Man because of its large, flat teeth.
Credit: National Museums of Kenya
This photo of casts of two palates demonstrates the large size of the teeth of Paranthropus boisei (left), an early human relative that lived in East Africa between 2.3 million and 1.2 million years ago and was known as Nutcracker Man. Much smaller teeth from a human skull are shown on the right.
Credit: Melissa Lutz Blouin, University of Arkansas
SALT LAKE CITY: The big-toothed ancient human relative known as 'Nutcracker Man' actually lived on a diet of grasses, not nuts, according to a new discovery that upsets conventional wisdom about early humanity's diet.
University of Utah and National Museums of Kenya researchers examined the Paranthropus boisei skull found in Tanzania in 1959, using pulverised tooth enamel to analyse the carbon isotope ratios that revealed what food these extinct human relatives were munching on.
"It most likely was eating grass, and most definitely was not cracking nuts," said lead author and geochemist Thure Cerling from the University of Utah of the study published in the current edition of the Proceedings of the National Academy of Sciences.
Study co-author Kevin Uno, also from the University of Utah, added: "This study provides evidence that Paranthropus boisei was not cracking nuts, but was instead eating mainly tropical grasses or sedges. It was not competing for food with most other primates, who ate fruits, leaves and nuts; but with grazers - zebras' ancestors, suids [ancestors of pigs and warthogs] and hippos."
Drilling for prehistoric dinners
Cerling and colleagues examined the tooth enamel of 24 teeth from 22 individuals who lived between 1.4 million and 1.9 million years ago. They were closely related to and once thought part of the genus of human ancestors named Australopithecus. Both extinct Paranthropus and the human genus Homo arose from Australopithecus.
The team used a drill to pulverise some tooth enamel into powder, but only 2 milligrams per tooth and only from the broken surface of broken teeth, leaving the original surfaces intact for future study. Still, there was anticipation among officials at the National Museums of Kenya, where the teeth are housed.
"The sound of the drill may make a lot of palaeontologists and museum staff cringe, but as the results of this study show, it provides new information that we can't get at any other way," Uno said. "And we've gotten very good at drilling."
More grasses than any other early human
Carbon isotope ratios in tooth enamel can reveal whether ancient animals ate plants that used what is called C3 photosynthesis - trees (and the leaves, nuts and fruits they produce), shrubs, cool-season grasses, herbs and forbs - or plants such as warm-season or tropical grasses and sedges that use what is known as C4 photosynthesis.
Sedges vaguely resemble grasses, but their stems' cross-sections usually are triangular, which means 'sedges have edges' when rotated between thumb and finger.
The study found that not only did the Nutcracker Man not eat nuts or other C3 plant products, but dined more heavily on C4 plants like grasses than any other early human, human ancestor or human relative studied to date. Only an extinct species of grass-eating baboon had a diet so dominated by C4 plants.
