Human ancestors may have used human-like hand postures much earlier in history than we thought.
Scientists produced the first-ever findings that reveal stone tool use in the pro-Homo human ancestral species Australopithecus africanus dates as far back as three million years ago, Kent University reported.
The abilities for forceful precision (such as turning a key) and "squeeze" gripping (such as using a hammer) are unique to humans and has been linked to two key evolutionary transitions in the history of hand use. The abilities are believed to have come about when climbing behaviors were reduced and humans started to create stone tools, but it has been unclear when exactly this transition occurred.
To make their findings the research team used groundbreaking techniques to determine how fossils used their hands by looking at the spongy structure within a bone called the trabeculae.This substance remodels itself quickly during life and can reveal the movements of its host, even millions of years later.
The researchers looked at the trabeculae of hand bones of humans and chimpanzees and found key differences between the two. The unique human pattern was found in human ancestral species that lived in South Africa between two and three million years ago and were not previously believed to have used stone tools. The fossils proved to have human-like trabecular bone pattern in the bones of the thumb and palm that suggested otherwise.
"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 researchers reported.
The findings were published in a recent edition of the journal Science.
