MIAMI - The hand structure of early human ancestors who lived 3.2 million years ago suggests they had the ability to grasp and use tools, even if they hadn't invented them yet, anthropologists said Thursday.
Until now, Australopithecus africanus, which lived two to three million years ago in what is now South Africa, were not believed to have made tools - the first evidence of which dates back to 2.6 million years ago - but their hands suggest otherwise, according to a study in the journal Science.
A creature with an ape-like face and long arms, but that had a large brain and walked upright on two feet, Australopithecus africanus appears to have descended from the trees, gained hand dexterity and became capable of fine motor movements.
The new findings are based on a new study of the internal spongy structure of bone, called trabeculae, which can reveal how the bones were used while the individuals were alive.
For instance, trabecular bones look very different in humans and chimpanzees, which cannot mimic the way a human hand can grip forcefully using thumb and fingers.
Neanderthal fossils, however, more closely resemble modern human hands in this regard. Neanderthals had the dexterity to use tools and make cave paintings.
Australopithecus, too, had "human-like trabecular bone pattern in the bones of the thumb and palm (the metacarpals) consistent with forceful opposition of the thumb and fingers typically adopted during tool use," the University of Kent said in a statement.
"These results support previously published archaeological evidence for stone tool use in australopiths and provide skeletal evidence that our early ancestors used human-like hand postures much earlier and more frequently than previously considered."
The study also included researchers from University College London, the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany and the Vienna University of Technology in Austria.