This indicates our long-gone relatives experienced a shift in their diet relatively early, at least in central Africa. These individuals survived in open landscapes with few trees, so apparently they could exploit not only dense woodland areas but also other environments.
Although the area where A. bahrelghazali roamed is now dry and hyper-arid, back in the day it featured a network of shallow lakes with nearby floodplains and wooded grasslands.
While this ancestor of ours clearly had big, impressive teeth, they would not have been able to tackle leaves day after day. The individuals also lacked cow-like guts to break down and digest such food, so the researchers suspect the early hominids probably relied more on the roots, corms and bulbs at the base of the plants.
Given the carbon isotope data, there is a very remote chance that the early hominids ate animals that, in turn, ate the tropical grasses.
"But as neither humans nor other primates have diets rich in animal food, and of course the hominins are not equipped as carnivores are with sharp teeth, we can assume that they ate the tropical grasses and the sedges directly," Lee-Thorp said.
The research was published in Proceedings of the National Academy of Sciences.
(Image: J.M. Garg)