Researchers from the University of Kansas have found the earliest evidence for right-handedness in the fossil record by examining striations on teeth of a Homo habilis fossil. The scientists studied the 1.8 million year-old fossil teeth, analysing the small cut marks or labial striations, which are on the lip side of the anterior teeth in an intact upper jaw fossil, known as OH-65, which was found in Olduvai Gorge in Tanzania.
“We think that tells us something further about lateralisation of the brain. We already know that Homo habilis had brain lateralisation and was more like us than like apes. This extends it to handedness, which is key,” said David Frayer, Professor Emeritus at the University of Kansas, US.
Frayer, in the study published in the Journal of Human Evolution said among the network of deep striations found only on the lip face of the upper front teeth, most cut marks veered from left down to the right. According to the study, the marks makes it likely that they came from when OH-65 used a tool with its right hand to cut food it was holding in its mouth while pulling with the left 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 added. Based on the direction of the marks, the researchers said that it’s evident the Homo habilis was right-handed.
“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,” the author added. If the researchers’ conclusion is right, that makes OH-65 the first potential evidence of a dominant-handed pre-Neanderthal, beating out previous fossil discoveries that showed right-handedness in individuals who lived around 500,000 years ago.