Humans, as we now know them, have been on Earth for about 400,000 years. Before them, a species known as Homo erectus ranged over our planet for about 1.5 million years. There is some debate about whether Homo erectus is a direct ancestor of Homo sapiens. Still, the species is the first in the fossil record to show the most humanlike features, including longer legs and shorter arms. They were also the first to use hand axes, like the one that was found in East Africa and recently described by a team of researchers from Japan, Hong Kong, and Ethiopia.
While researchers have previously found Homo erectus hand axes in Africa, this find was unique because the ax was made from bone, not stone, which is harder and much more prevalent in the fossil record. The ax was unearthed at an archaeological site in Ethiopia called Konso-Gardula and is only the second ax to be found that’s made by bone by a member of the Homo Erectus species.
The researchers concluded that the ax was made from the bone of a hippopotamus and that it dates to about 1.4 million years ago. With its handle, it would have been about 13 cm long and showed signs of use–most likely from the butchering of meat–including scars, polish caused by wear, rounding of the edges, and striations.
The find further reinforces the idea that members of the Homo erectus species were intelligent and skilled at making tools, although the researchers are unsure of why the ax was made from bone rather than stone, which is harder.
A paper describing the find has been published in the Proceedings of the National Academy of Sciences.