According to the researchers from the University of Kansas, they found out the most primitive proof for right-handedness after examination of the fossil records and striations on the teeth of a Homo habilis fossil.

The researchers studied the 1.8 million year-old fossil teeth of the Homo habilis which was discovered in Olduvai Gorge in Tanzania. They had analysed and worked on the small cut marks or labial striation which can be found on the lip side of the anterior teeth in an intact upper jaw fossil, known as OH-65.

"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," David Frayer, Professor Emeritus at the University of Kansas, United States, said in an interview.

In the research published in the Journal of Human Evolution, Frayer said that most cut marks veered from left down to the right were among the network of deep striations found only on the lip face of the upper front teeth. Based on the study, the marks that were found were likely came from when OH-65 used a tool or object with its right hand to cut the food that it was holding in its mouth while pulling it with the left hand.

Frayer furthered that the experimental work has shown that the 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.

Homo habilis is one of the earliest members of the genus Homo. It has a slightly larger braincase and smaller face and teeth than in Australopithecus or older hominin species. However, it still retains some ape-like features, including long arms and a moderately-prognathic face.

The researcher added that the 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.

If this theory is correct, that makes OH-65 of the Homo habilis the first potential evidence of a dominant-handed pre-Neanderthal, overtaking the previous fossil discoveries that showed right-handedness in individuals who lived around 500,000 years ago.