Neanderthals and their likely ancestors were overwhelmingly right-handed, according to investigation into fossilized teeth excavated in Spanish and other European caves.
Writing in the British journal Laterality, an international team of researchers has concluded that right-handedness, a uniquely human trait that has right-handers outnumbering lefties nine-to-one, was the dominate pattern as far back as a half million years ago.
Various researchers have attempted to determine when right-handedness first evolved by analyzing ancient tools, prehistoric art and human bones.
However, the results have not been definitive.
“We found that the best evidence comes from teeth,” David Frayer, professor of anthropology at the University of Kansas, told Discovery News.
Frayer and colleagues examined fossilized teeth from a more than 500,000-year-old chamber known as Sima de los Huesos near Burgos, Spain.
Excavated over the past quarter century, the cave has produced a trove of human remains believed to be the ancestors of European Neanderthals.
The researchers investigated the incisor and canine teeth of 12 individuals whose estimated age ranged from 9.5 years to more than 35 years.
Neandertals from Krapina and Vindija (Croatia) and sites in France comprised the Neandertal sample, dated from 130,000 to about 30,000 years ago.
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Quite different from the finer dietary scratches on the buccal face of premolars and molars, the wider and longer markings only on the lip face of incisors and canines were probably made as humans used their front teeth like a third hand, maneuvering food and other objects clenched between them.
Produced over the lifetime of the individuals, the scratch marks were made when a stone tool was accidentally dragged across the labial face.
“Pulling with the left and cutting with the right leaves oblique scratches of a typical direction, if the stone tool accidentally hits the tooth,” Fraser said.
“Pulling with the right and cutting with the left leaves the opposite oblique marks,” he added.
Incisions angled to the right, the result of right-handed tool use, characterized all 12 individuals from Sima de los Huesos, suggesting that no left-handers were present in the sample.
Two individuals in the later Neanderthal sample had left-oblique striations typical of left-handers, resulting in an 93.1 percent of right-handedness in the total sample.
"It is difficult to interpret these fossil data in any way other than that laterality was established early in European fossil record and continued through the Neandertals," the researchers wrote.
"This establishes that handedness is found in more than just recent Homo sapiens," they said.
According to Frayer, these findings can shed light in understanding the language capacity of ancient populations, as language is primarily located on the left side of the brain, which controls the right side of the body.
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"The general correlation between handedness and brain laterality shows that human brains were lateralized in a 'modern' way by at least half a million years ago and the pattern has not changed since then," wrote the the researchers.
“There is no reason to suspect this pattern does not extend deeper into the past and that language has ancient, not recent, roots,” they concluded.
Photo: Pulling with the left and cutting with the right leaves markings angled to the right; upper central incisor with manipulative marks highlighted (primarily right-handed type) Courtesy David Frayer.
Tags: Archaeology
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