Scientists at the National Museums of Kenya, in collaboration with researchers from the University of Utah, Stony Brook University, the University of Colorado at Boulder and the Turkana Basin Institute, are now certain that a 2.3 million-year-old human relative nicknamed ‘Nutcracker Man’ never actually ate nuts despite possessing big, flat molar teeth and a powerful jaw.

Paranthropus boisei, discovered by Mary and Louis Leakey in 1959 at Olduvai Gorge in Tanzania, instead fed on grass.

In a study published in the online edition of the journal Proceedings of the National Academy of Sciences, it has now been revealed that Nutcracker Man lived on grasses and sedges. This new discovery puts to question earlier claims of what could have constituted the diet of early man.

The study further suggests that Paranthropus boisei may have been competing with grazers such as the ancestors of present-day Zebras, Suids (ancestors of pigs and Warthogs) and hippos.

The study found that Nutcracker Man fed heavily on the C4 group of plants such as grasses more than any other early human or human relative studied to date with the exception of a species of grass-eating baboon that is now extinct.

Scientists study the ratios of Carbon isotopes in tooth enamel to reveal the plant diets of ancient animals. These isotopes are based on the two types of photosynthesis (C3 and C4) which occur in plants.

Trees, including the leaves, nuts and fruits produce shrubs, cool-season grasses, herbs and forbs make use of C3 photosynthesis. Plants such as warm-season or tropical grasses and sedges, on the other hand, use C4 photosynthesis (ScienceDaily, May 3, 2011)

When the researchers studied 24 teeth obtained from 22 individuals, they found that 77% of Paranthropus boisei’s diet consisted of C4 plants such as grasses. The teeth further revealed that ‘Grass Eater Man’, as he is now called, lived in semi-arid savannah with woodlands along rivers or lakes.

Paranthropus boisei’s fossils revealed the species that lived in East Africa (including Kenya and Ethiopia) from 2.3 million to 1.2 million years ago. The short creatures had big, flat premolars and molars; thick tooth enamel; muscle-attachment surfaces for large chewing muscles; and powerful jaws. It is these characteristics that earned Paranthropus boisei the nickname Nutcracker Man – a name coined by South Africa’s paleoanthropologist and a close friend of the Leakeys, Phillip Tobias.

This new discovery changes half a century of scientific evidence which will cause the world to re-examine the whole theory of how our dietary patterns have evolved over time.