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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.
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