A study found the earliest evidence that human beings have been using their right hand because of early lateralization of the brain, which separates us from apes. The research that analyzed a Homo habilis fossil could lead to the study of more fossils to discover the true origin of brain lateralization.
A team from the University of Kansas found the earliest evidence of right-handedness in a 1.8 million-year-old fossil that belonged to a Homo habilis. David Frayer, a Kansas University professor emeritus of anthropology and the lead author of the study said that the findings tell new information about brain lateralization.
Frayer continued and stated that lateralization of the brain was already known when it came to the Homo habilis, but discovering handedness is key. Brain lateralization makes us less like apes and learning that the Homo habilis fossil shows evidence of right-handedness is essential to evolutionary studies.
The Kansas University team determined the characteristic after analyzing small cut marks – labial striations – found in a stream channel of the Olduvai Gorge in Tanzania. Labial striations are the lip side of the anterior teeth in the intact upper jaw fossil, known as OH-65.
Frayer stated that the experimental work they performed showed that the scratches were most likely produced when the specimen used a stone tool to process material gripped between the anterior teeth and the device occasionally struck the labial face, leaving a permanent mark on the tooth’s surface.
The direction of the marks is what suggest that the Homo habilis fossil belong to a right-handed human. The Kansas University team has only analyzed one fossil, but this is the first time anthropologists have found evidence of a dominant handed pre-Neanderthal, according to Frayer. This research could inspire other studies to find out of the marks of other early Homo fossils show the same evidence.
“One specimen does not make an incontrovertible case, but as more research is done and more discoveries are made, we predict that right-handedness, cortical reorganization, and language capacity will be shown to be important components in the origin of our genus,” stated Frayer in the report.
The analysis of the Homo habilis fossil and first proof of brain organization
Frayer added that the network of deep striations was only found on the lip face of the upper front teeth and emphasized that the cut marks veered from left down to the right. The study came to the conclusion that the Homo habilis got those marks when it used a tool with its right hand to cut food.
OH-65 held the instrument in its mouth while pulling with the left hand. According to the study, the scratches can be seen with the naked eye. Still, the team used a microscope to determine their alignment and to quantify their angulation.
Many other studies point to the likelihood that brain reorganization, the use of tools and the use of a dominant hand happened early in the human lineage. Apes are estimated to be as skill with their right hand as with their left hand, an almost 50-50 relationship. Contrary to what happens to humans.
Today, researchers estimate that 90 percent of people are right-handed and the discovery could indicate that humans have been that way from more time than it was thought.
Frayer believes that his work could be not only the evidence for early brain lateralization but handedness and possibly language. The findings were published this week in the Journal of Human Evolution
Source: Phys.org