'Nutcracker Man' wasn’t so nutty

By PETER ORENGO and AFP

He traversed across East Africa two million years ago and had the powerful jaws and big chompers to crack the toughest of shells, but a new study shows that the ancient human relative "Nutcracker Man" actually preferred to munch on grass.

With molars about triple the size of a modern man’s, the human ancestor, Paranthropus boisei, apparently used his big, flat molar teeth and powerful jaws to chew on grass instead of hard nuts.

A skull found in Tanzania in 1959 quickly drew the nickname "Nutcracker Man" because of its giant teeth but National Museums of Kenya and University of Utah researchers now say the species grazed on the same wild fields as the ancestors of zebras, pigs and hippos.

NMK Head of Sciences Dr Emma Mbua explains the structures of ancient human relatives’ skulls (from left) Homo Sapiens and "Nutcracker Man". [PHOTO: boniface okendo]

By grinding a portion of the Nutcracker Man’s tooth, scientists were able to analyse the carbon isotope ratios to determine exactly what kind of food he ate. Carbon isotope ratios in tooth enamel reveals whether ancient animals ate plants that use C3 photosynthesis or C4 photosynthesis.

The discovery that was announced in Nairobi and the US changes conventional wisdom about early human’s diet.

Special drill

"The study proves the Paranthropus boisei was not cracking nuts but instead eating tropical grasses or sedges. It means it was not competing for food with other primates, who ate fruits, leaves and nuts; but rather with grazers such as ancient zebras, pigs and hippos," said Dr Emma Mbua, a senior Research Scientist specialising on Earth science.

Only one similar diet has been seen in an extinct species of grass-eating baboon, the researcher said.

The researchers analysed samples from the teeth of about 22 Paranthropus boisei individuals who lived between 1.4 million and 1.9 million years ago.

This species was once thought part of the genus of human ancestors named Australopithecus. The researchers also analysed oxygen isotope composition in the fossil teeth, which indicated paranthropus boisei lived in semi-arid savannah with woodlands along rivers or lakes.

To obtain a necessary sample, a special drill was used to pulverize some tooth enamel into powder. Only two milligrams of the powder per tooth was obtained from the broken surfaces, leaving the original surfaces intact for future studies. The powder was then taken to Utah University for study.

In tropical environments, virtually all trees and bushes use the so-called C3 photosynthetic pathway to convert sunlight into energy, while savannah grasses and some sedges use the C4 photosynthetic pathway. C3 photosynthesis is found in trees and leaves, nuts and fruits, shrubs and cool-season grass.

Mbua said the isotope analysis indicated Nutcracker Men were much bigger fans of C4 grasses and sedges than C3 trees, shrubs and bushes. "We found out that not only did the Nutcracker Man eat no nuts but dined more heavily on C4 plants like grasses than any other early human or human ancestor studied to date," said the Scientist based at the Museum of Kenya.

Diet from grass was also found to average 77 per cent, statistically indistinguishable to grazing animals like zebras, pigs and warthogs.

The new findings may provoke a major change in how we view the diets of other early humans. Much of the previous work has been on the size and shape of the teeth, along with micro-wear analysis.

"The results are completely different than the conclusions based on over 50 years of researching along those lines," said Mbua. Consequently other past conclusions about other species may also require revision.

For decades, scientists have believed human ancestress in the genus Australopithecus, which gave rise to now extinct paranthropus boisei and homo, or early humans, had head and tooth features suggesting they ate substances like nuts.