It seems that we may have more in common with some of the earliest ancestors of humans than we originally thought. According to a new study published in the journal Science, anthropologists from the University of Kent, the University College London, the Max Planck Institute for Evolutionary Anthropology in Leipzig (Germany) and the Vienna University of Technology (Austria) now believe that some of the earliest human ancestors who lived 3.2 million years ago had hand structures much like our own and were able to grasp and use tools, even if they had not invented them yet.
Australopithecus africanus, which lived two to three million years ago in what is now South Africa, were not believed to have made tools, with the earliest evidence of tool making dates back to 2.6 million years ago. But their hands now suggest otherwise.
This early ancestor of man possessed an ape-like face with long harms, but had a large brain and walked upright on two feet. Evidence points to the early species of humans descending from the trees, while gaining hand dexterity and becoming capable of fine motor movements.
Dr Matthew Skinner, Senior Lecturer in Biological Anthropology and Dr Tracy Kivell, Reader in Biological Anthropology, both of Kent's School of Anthropology and Conservation, used new techniques to reveal how fossil species were using their hands by examining the internal spongy structure of bone called trabeculae.
Trabeculae can reveal how bones were used while individuals were alive. For example, if you examine the trabecular bones of humans and chimpanzees, they will look very different. This is due to the fact that chimpanzees cannot mimic the way a human hand can grip forcefully using the thumb and fingers.
The distinctly human ability for forceful precision (e.g. when turning a key) and power "squeeze" gripping (e.g. when using a hammer) is linked to two key evolutionary transitions in hand use: a reduction in arboreal climbing and the manufacture and use of stone tools. However, it is unclear when these locomotory and manipulative transitions occurred.
This unique pattern from humans is also present in Neanderthal fossils, as well revealing how human-like their hands actually were. Neanderthals possessed the ability and the dexterity to both use tools and even create 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 researchers from the University of Kent say.
"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."
