The results of a new study suggest that tool-making may have been undertaken by a distinct human genus.
Scientists had previously thought that tool-making was specific to the genus Homo, ancestors of the Homo sapiens. However they have now discovered hand characteristics which would have made tool-making possible for at least one species of the genus Australopithecus.
Homo habilis are thought of as the ancestors of tool-making hominins, but now it would appear that Australopithecus africanus can also stake a claim to having made tools in their southern African homes around 2-3 million years ago.
Ancestors making tools: Ongoing debate
There has been seemingly endless debate over which human ancestor was the first to make a tool, and now a team of researchers led by the University of Kent has added its voice to proceedings.
The main focus of the study was the density and shape of the hand bones of various species across several million years, with particular interest taken in the metacarpal bones, which fan out from the wrist to each individual digit. Changes in the structure of these bones can inform us as to whether our ancestors still lived in the treetops, or were now using their forelimbs for more delicate tasks.
Changing bone structure
The scientists had to deal with an incomplete fossil record, with fragmentary evidence suggesting that Homo erectus was the first species to develop the modern hand, around 1.4 million years ago. By examining the hands of ancient Egyptians and recent Europeans and comparing them with chimpanzees and bonobos, the team were able to draw up a more complete picture to compare A. africanus with.
Their work shows that the density of the metacarpal bones had shifted away from the fingers and towards the palm, suggesting that the motion of squeezing the thumb towards their fingers was common.
However this does not mean A. africanus possessed a modern hand, far from it. In fact much of its hand structure was consistent with characteristics required for swinging around the treetops. Most scientists believe that the early hand adapted because of the advantages of tool-making, but other features could still have been present.
It would seem that it was not only the genus Homo that learned the value of tools.