By studying modern-day baboons in Kenya, researchers say they've solved the mystery behind an apparent skeletal discrepancy in an ancient hominin who roamed East Africa between 2.4 million and 1.4 million years ago.

Remains of Paranthropus boisei, also known as the Nutcracker Man, indicate the early human relative had strong jaws, suggesting a diet of hard foods such as nuts, and yet teeth seemingly made for soft foods. Past research has also suggested the hominin's diet was made up mostly of so-called C4 plants, which include grasses and sedges. However, whether this could sustain a large-brained, medium-sized creature like the Nutcracker Man remains a matter of debate.

Led by Gabriele Macho, an archaeologist from Oxford University, the new study points to a new solution to the puzzle: C4 tiger nuts.

According to her report, published in the journal PLOS One, baboons living in Kenya's Amboseli National Park - an environment, she argues, similar to the one the Nutcracker Man would have lived in - eat large amounts of C4 tiger nuts. Not only would this food have had the minerals, vitamins and fatty acids needed for the hominin brain, Macho said, but it would also help to explain evidence of damage to tooth enamel found on fossils belong to the Nutcracker Man. Corroborating the latter theory is the presence of similar abrasions on the baboons' teeth.

In order to take full nutritional value of the tiger nuts, the Nutcracker Man would have had to chew them for a substantial amount of time, allowing the enzymes in their saliva to break down the starches. This, Macho notes, would explain the human relative's cranial anatomy.

"Tiger nuts, still sold in health food shops as well as being widely used for grinding down and baking in many countries, would be relatively easy to find," Macho said. "They also provided a good source of nourishment for a medium-sized hominin with a large brain. This is why these hominins were able to survive for around one million years because they could successfully forage - even through periods of climatic change."