Human right-handedness: 500,000 years and counting

Outside of the occasional southpaw jamboree, it's clear that modern humans are a decidedly right-handed species. In fact, righties outnumber lefties by a 9 to 1 ratio - and have for quite some time.

500,000 years, at the minimum, according to a new paper.

In a recent piece in the British journal Laterality, lead author David Frayer, professor of anthropology at the University of Kansas, recounts how his team studied the markings on fossilized front teeth to arrive at their conclusions. Their investigation led them to the finding that right-handedness is not something specific to (more recent) Homo sapiens. Rather, the researchers discovered telling links between the markings on the fossilized teeth and the right or left-handedness going back to prehistoric humans.

Working with specimens from what were believed to be ancestors to the Neanderthals in de los Huesos near Burgos, Spain, the team - which also studied teeth samples from subsequent Neanderthal populations in Europe - uncovered a correlation between handedness and brain laterality, concluding that "human brains were lateralised in a ''modern'' way by at least half a million years ago and the pattern has not changed since then."

"These marks were produced when a stone tool was accidentally dragged across the labial face in an activity performed at the front of the mouth," Frayer explained in a statement from the University of Kansas "The heavy scoring on some of the teeth indicates the marks were produced over the lifetime of the individual and are not the result of a single cutting episode."

Indeed, their findings testified to the overwhelming preference for right-handedness with more than 93% of the samples taken from the Sima de los Huesos and European Neanderthal sites pointing to evidence of right-handedness.

"It is clear that by the Middle Pleistocene there was already a strong bias towards the use of the right hand for manipulations performed at the front of the mouth," according to the paper.