Evidence Of Right Handedness Found In Homo Habilis Fossil
Dominant hand preference in humans is a trait that scientists are still trying to understand, but new evidence may show that whatever its purpose, the existence of dominant hands might stretch back way further than previously thought. A study published in Journal of Human Evolution finds proof for right handedness in Homo habilis, a pre-human homo species that existed 1.8 million years ago.
"This is an exciting paper because it strongly suggests right-handed tool use in early Homo around 1.8 million years ago," Debra Guatelli-Steinberg, an anthropologist at the Ohio State University, told Christian Science Monitor.
The study, authored by David Frayer, a paleoanthropologist at the University of Kansas, began when Frayer noticed strange scratch marks on a Homo habilis teeth fossils. These scrapes on the outside of the teeth look as if they were dragged from right to left. It looked like something that might happen to an animal that was using its right hand dominantly.
Frayer and his colleagues conducted an ingenious study to prove this hypothesis. Subjects wearing mouth guards that easily recorded scratches tore meat and other materials while using their mouth as a "third hand". These marks showed similarities with those found on the H. habilis fossil.
The team's idea is that ancient pre-humans used their mouth and left hand to hold meat, while they sliced it into smaller pieces with a tool made of rock. When they missed the meat, the tool would hit their teeth, leaving scratches that go diagonally downward from right to left. It's long been known that H. habilis used stone tools, so this theory isn't out of the realm of possibility.
Christian Science Monitor notes:
Frayer points out that the team tallied 559 marks on the teeth and almost 47 percent align with what would be expected to be produced by this right-handed behavior. In contrast, he says, just about 11 percent appear to have been produced by a left-handed cutting motion.
But not everyone backs up the study's findings. "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," Bernard Wood, a paleoanthropologist at George Washington University told Christian Science Monitor. "It's a really interesting observation that only time will tell whether that observation has been over-interpreted."
More research will likely need to be done before we have a solid answer on this question, but at the very least this new evidence suggests that hand dominance could have a much longer history than previously thought.
Source: Christian Science Monitor
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