The carbon composition of enamel in early hominin teeth, supported by soil sample evidence, suggests our ancestors were dietary generalists, able to eat a wide variety of plants that grow in both semi-arid and wooded areas.
Paranthropus boisei and Homo rudolfensisare coexisted roughly 2.4 million years ago near Lake Malawi in the East African Rift system, where they ate large amounts of C3 plants, which today include beans, rice, and potatoes. But by two million years ago, Paranthropus shifted their plant preferences as they moved to hotter, drier areas, according to a new study by a group of paleontologists, led by Tina Lüdecke of the Senckenberg Biodiversity and Climate Research Centre in Frankfurt, Germany.
The researchers conclude that during the Early Pleistocene, hominins showed “a high versatility in the diverse habitats of the East African Rift system”.
Lüdecke and her team analyse the enamel of fossilised teeth from the region, as well as soil samples.
Plants are generally either C3 or C4 types, depending on the number of carbon atoms in the molecules created during photosynthesis. C3 plants occur in more temperate climates, are thought to have evolved earlier than C4 plants, and are woodier.
C4 plants make up only 5% of existing plant biomass. They include grasses, corn, and sugarcane, and can withstand warmer temperatures.
Since animals, including humans, use carbon from plants to form enamel, looking at carbon isotopes in it can help determine what type of plant matter an organism ate. (The isotopes can also be passed on from meat. Someone with an all-beef diet, for example, would carry isotopes from the cow’s food.)
Lüdecke’s team also looked at isotope data from soil at the fossil sites, which helped them reconstruct the temperature data for the region. This data support their findings that P. boisei and H. rudolfensis were dietary generalists.
“Collectively, the stable isotope and faunal data presented here document that early Homo and Paranthropus were dietary opportunists and able to cope with a wide range of paleohabitats, which clearly demonstrates their high behavioral flexibility in the African Early Pleistocene,” the scientists write in the journal Proceedings of the National Academy of Sciences.
Behavioural flexibility is considered a key component to survival, so these findings could help explain why humans are here today.