Our ancient ancestors who lived in East Africa between 2.4 million-1.4 million years ago survived mainly on a diet of tiger nuts, which are edible grass bulbs still eaten in parts of the world today, finds an Oxford University study.
The study also suggests that these early hominins may have sought additional nourishment from fruits and invertebrates, like worms and grasshoppers.
Study author Dr Gabriele Macho examined the diet of Paranthropus boisei, nicknamed "Nutcracker Man" because of his big flat molar teeth and powerful jaws, through studying modern-day baboons in Kenya.
Her findings help to explain a puzzle that has vexed archaeologists for 50 years.
Scholars have debated why this early human relative had such strong jaws, indicating a diet of hard foods like nuts, yet their teeth seemed to be made for consuming soft foods. Damage to the tooth enamel also indicated they had come into contact with an abrasive substance.
Tiger nuts, which are rich in starches, are highly abrasive in an unheated state. Dr Macho suggests that hominins' teeth suffered abrasion and wear and tear due to these starches.
The study is published in the journal, PLOS ONE.