It’s not hard to understand why Paranthropus boisei is often called the Nutcracker Man. The hominid’s massive molars and enormous jaw make it seem pretty obvious that the species spent a lot of time chomping on hard nuts and seeds. Yet, the only direct evidence of P. boisei‘s meals—the chemistry and microscopic scratches of the teeth—hint that the species probably didn’t crack nuts all that much, instead preferring the taste of grass. A team of anthropologists that recently reviewed the possible diets of several early hominid species has highlighted this paradox of the Nutcracker Man and the difficulties in reconstructing the diets of our ancient kin. The first place anthropologists start when analyzing diet is the size and shape of the hominid’s teeth and jaws. Then they look for modern primates that have similar-looking dentition to see what they eat. For example, monkeys that eat a lot of leaves have molars with sharp cusps for shearing the tough foliage. On the other hand, monkeys that eat a lot of fruit have low, rounded molar cusps. If you found a hominid with either of those traits, you’d have a starting point for what the species ate. But the morphology of a species’ teeth and jaws only shows what the hominid was capable of eating, not necessarily what it typically ate. In some cases, these physical traits might reflect the fallback foods that a species relied on when its preferred foods were unavailable during certain times of the year.