A team of researchers from Japan, Hong Kong, and Ethiopia have discovered a surprisingly sophisticated hand axe that they believe was made by a direct human ancestor in what is now modern Ethiopia.
The scientists presented their analysis of the hand axe, which is one of few similar ancient axes to be made from bone, in a paper published in Proceedings of the National Academy of Sciences.
Archaeologists and scientists have previously discovered and studied hand axes made by members of Homo erectus, a species that is thought to be a direct ancestor of Homo sapiens — humans.
These hand axes were typically made by chipping and crafting bits of stone to make a sharp edge. In the new paper, the researchers detail their discovery of a hand axe made from bone — only the Homo erectus-made axe made from bone to ever be found.
The axe's discovery location suggests it is approximately 1.4 million years old. Analysis of the axe showed it was made from the thigh bone of a hippopotamus. It was sharpened by another tool — likely a hard rock — and it is roughly 13 centimeters long.
The axe's oval design is similar to that of hand axes made of stone, the researchers explain in a press release. They also found evidence that the hand axe had been used — signs of wear included rounding of edges and striae patches.
According to the researchers, the construction of the axe is quite sophisticated for the period. It shows that members of Homo erectus were more skilled in tool making than previously thought, which also suggests that they might have had more intelligence than scientists previously believed.
While the researchers say the axe was likely used to butcher animals in order to make their meat easier to eat, they could not explain why the toolmaker decided to use bone as the main material — despite the fact that there would have been many stones in the area.