Fossils from the “handy man” of the human family tree have now provided the oldest known evidence of right-handedness in our lineage.

The discovery comes from a 1.8-million-year-old upper jawbone of Homo habilis, a human ancestor who lived in eastern and southern Africa from 2.4 to 1.4 million years ago. Scientists suspect the species was a regular user of stone tools, which are found in abundance around the fossil discovery site.

The jawbone’s teeth, still firmly in place, are covered in diagonal scratches that were most likely made when this Homo habilis individual, perhaps a female, accidentally nicked her teeth with a stone tool held in her right hand.

While the Homo habilis jawbone is a sample size of one, its