Experts have often wondered why most people - estimating 90 percent of the Earth's population - are right-handed. New research suggests that this preference dates back millions of years ago based on teeth markings from early human fossils.

The study was published in "Journal of Human Evolution" and stated that evidence for right-handedness is seen in Homo habilis, a pre-human species that existed around 1.8 million years ago. The said evidence are scrapings on the outside of the teeth fossil that indicated it started from left and veering lateral to the right.

Researchers Explained The Origin Of The Teeth Markings Found On Early Human Fossil

Researchers explained that this was likely because our ancestors were using their right hand to hold a tool; their left to grip a slab of meat, and their mouth acting as a "third hand." Given this position, they would then use their right hand to cut the food, while using their mouth and left hand to pull the morsel away, explained Popular Mechanics.

It's likely that on occasion, their right hand would slip and would end up scraping the upper teeth resulting in the permanent surface markings. To test this hypothesis, paleoanthropologist David Frayer and his colleagues conducted a clever study.

They gathered subjects and had them wear mouth guards that easily recorded scratches. Participants were then instructed to tear a piece of meat and other materials and used their mouth as a "third hand." The resulting markings on the mouth guards were similar to the scratches found on the fossil, reported the Daily Mail.

Teeth Markings Not Indicative Of Right-Handedness, Said Another Expert

However, paleoanthropologist Bernard Wood, who was not part of the study, warns Frayer and his colleagues not to jump to conclusions. "My concern is that they really don't spend enough time on other explanations for these phenomena, the presence of these scratches and their directionality," Wood told Christian Science Monitor. "It's a really interesting observation that only time will tell whether that observation has been over-interpreted."

The study also included only a single specimen to reach their conclusion. This is the first time that researchers connected right-handedness to teeth markings found on early human teeth fossils.