When it comes to carrying out tasks, humans have developed a preference for one hand over the other. Today, right-handedness is dominant with almost nine out of ten people preferring their right hand to lift objects and do tasks like writing.

New research has found that this has been around a lot longer than originally thought. A team of scientists, led by David Frayer, a paleoanthroplogist at the University of Kansas, have published new evidence that the preference of using the right hand existed in a pre-human species called Homo habilis.

“This is an exciting paper because it strongly suggests right-handed tool use in early Homo around 1.8 million years ago,” Debra Guatelli-Steinberg, an anthropologist at the Ohio State University, who was not part of the research, told Christian Science Monitor.

Examining a fossil found in Tanzania containing teeth of a Homo habilis from 1.8 million years ago, the team noticed distinct scratch marks on the teeth that seemed to go in the direction of left to right indicating that it was holding something in its right hand.

“Experimental work has shown these scratches were most likely produced when a stone tool was used to process material gripped between the anterior teeth and the tool occasionally struck the labial face leaving a permanent mark on the tooth’s surface,” Frayer said.

In other words, the Homo habilis used its mouth as a third hand while using its right hand as a tool to cut the meat. The dominance of the right hand is the earliest anyone has found. Frayer and his team decided to re-enact the experiment using mouth guards and sure enough the same scratches appeared when using their right hand.

This is an exciting find and will go towards understanding handedness through evolution and how its connected to the brain.

“Handedness and language are controlled by different genetic systems, but there is a weak relationship between the two because both functions originate on the left side of the brain,” stated Frayer. “One specimen does not make an incontrovertible case, but as more research is done and more discoveries are made, we predict that right-handedness, cortical reorganization and language capacity will be shown to be important components in the origin of our genus.”

Details of the research was published in The Journal of Human Evolution.