What ancient people ate and how it changed their bodies

Changes in diet played a key role in the physical evolution of early humans, a study by scientists at Dartmouth College has found.

The scientists found that ancient hominids began eating hard herbaceous plants - cereals and their underground parts - long before they had teeth suitable for it. These conclusions were reached after analysing fossilised teeth and isotopic traces of food left in them millions of years ago.

The researchers examined teeth from different hominid species, from Australopithecus afarensis, who lived about 3.8 million years ago, to Homo ergaster, who lived about 2 million years ago. Particular attention was paid to changes in the shape and size of molars, because they are involved in chewing coarse plant food.

It turned out that already the most ancient ancestors of man began to include herbs and their roots in their diet, although their teeth were not yet adapted to this type of food. The first signs of consumption of carbohydrate-containing underground organs of plants - tubers, bulbs and rhizomes - appeared about 2.3 million years ago, but a significant restructuring of the structure of teeth occurred only after 700 thousand years. Only by Homo ergaster molars became longer and better coped with chewing hard plant tissues.

The authors of the work consider this evidence that hominids first changed behaviour - adapting to new food sources - and only then there were anatomical changes. Thanks to this flexibility, early humans were able to survive and develop in new, often harsh conditions, for example, on the expanse of the savannah after leaving the forests.

Interestingly, similar changes were observed in other primates living at the same time: great apes and colobus also began to eat grasses and sedges, despite lacking the necessary teeth or digestive systems.

At a certain point in human history, there was a leap: with the advent of regular access to underground plant parts, hominids were able to get a lot of energy from tubers and bulbs. This ensured not only survival, but also brain development, because such products are rich in carbohydrates and available all year round. Having already mastered stone tools, ancient humans could easily extract these supplies, with little or no competition from other animals.

The study highlights: the ability to adapt to changing environmental conditions through behavioural flexibility was a crucial factor in the success of human evolution.

"The ability to benefit from cereal plants is perhaps the secret of success that distinguished hominids from other primates," concludes Professor Nathaniel Dominy, one of the authors of the paper.