Research suggests human ancestors were right-handed

The researchers from the University of Kansas have discovered the earliest known evidence of right-handedness in the fossil record, which was found in Olduvai Gorge in Tanzania.

The 1.8 million year-old fossil teeth, known as OH-65, belongs to Homo Habilis Fossil, the first human species to make stone tools, proves that our ancestors were right-handed like modern humans.

David Frayer, is lead author on a recent study, made the discovery with his team by analyzing labial striations – small cut marks, which are lip side of the anterior teeth in the intact upper jaw fossil.

Frayer said among the network of deep striations found only on the lip face of the upper front teeth mostly cut marks veered from left down to the right. It is found from the analysis that the marks occurred when they use a tool with its right hand to cut food it was holding in its mouth whereas use left hand for pulling. The scratches can be seen with the naked eye, but a microscope was used to determine their alignment and to quantify their angulation.



“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.

But because this is the first potential evidence of a influential handed pre-Neanderthal, Frayer said, the study could lead to a search for the marks in other early Homo fossils

Although scientists have learnt a lot about “handedness”, they still haven’t been able to precisely explain why humans biased using one hand over the other, or why human populations are in the favor of right handedness over left handedness.

Researcher’s estimate that 90% of humans are right-handed, which differs from apes which are closer to a 50-50 ratio. Until now, no one looked for directionality of striations in the earliest specimens representing our evolutionary lineage.

The findings were published online this week in the Journal of Human Evolution.


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