London: Our very early ancestors in central Africa subsisted on a diet of tropical grasses and sedges between three and 3.5 million years ago, says a new finding.
An international team extracted information from the fossilized teeth of three Australopithecus bahrelghazali individuals -- the first early hominins excavated at two sites in Chad.
Julia Lee-Thorp, professor from Oxford University with researchers from Chad, France and the US, analysed the carbon isotope ratios in the teeth and found the signature of a diet rich in foods derived from C4 plants, the journal Proceedings of the National Academy of Sciences reports.
Lee-Thorp, a specialist in isotopic analyses of fossil tooth enamel, from the Research Lab for Archaeology and the History of Art, said: "We found evidence suggesting that early hominins, in central Africa at least, ate a diet mainly composed of tropical grasses and sedges."
"No African great apes, including chimpanzees, eat this type of food despite the fact it grows in abundance in tropical and subtropical regions," she said.
"The only notable exception is the savannah baboon which still forages for these types of plants today. We were surprised to discover that early hominins appear to have consumed more than even the baboons," Lee-Thorp said.
The finding is significant in signalling how early humans were able to survive in open landscapes with few trees, rather than sticking only to types of terrain containing many trees, according to an Oxford statement.
This allowed them to move out of the earliest ancestral forests or denser woodlands, and occupy and exploit new environments much farther afield, says the study.
The fossils of the three individuals, ranging between three million and 3.5 million years old, originate from two sites in the Djurab desert. Today this is a dry, hyper-arid environment near the ancient Bahr el Ghazal channel which links the southern and northern Lake Chad sub-basins.