Ancient Signs Of Toothpick Use May Point To Evidence Of Early Meat-Eating Hominids

FAYETTEVILLE, Ark. - A small bite of pre-history taken from the bottom of a gully at Olduvai Gorge in Tanzania may offer clues to the evolution of early humans’ diet, according to a University of Arkansas researcher.

Peter Ungar, associate professor of anthropology, will present his findings on the oldest evidence of toothpick use, extracted from a tooth unearthed in excavations at the gorge, at the American Association of Physical Anthropology annual meeting in San Antonio, Texas on Thursday, April 13.

Ungar and his colleagues Fred Grine, SUNY Stony Brook; Mark Teaford, Johns Hopkins University; and Alejandro Perez Perez, University of Barcelona, Spain, study teeth of human ancestors and modern-day primates to chart the evolution of diet in the genus Homo. Their timeline for the evolution of diet may contain clues to today’s diet-related health problems.

The tooth from Olduvai Gorge, one of the last artifacts plucked from the site by the Leakeys, was included in their research. The remains found by Mary Leakey and her colleagues at Olduvai helped date some of the earliest ancestors of human beings, dating back as far as 1.8 million years.

When Ungar and his colleague were cleaning the Olduvai tooth for examination, they noticed some strange grooves on it.

When the researchers probed the tooth using scanning electron microscopy, they found tiny, parallel lines that repeated along the sides of the tooth.

The size, shape and orientation of the grooves point to evidence of someone trying to shove something narrow into a small space between their teeth - early traces of toothpick use, Ungar believes. The object would have to have been sharp to leave marks on the enamel and the dentin - the hominids may have used pieces of bone, or grit on a stick may have caused the grooves.

Evidence of toothpick use - engraved in enamel - spans time from 1.8 million years ago to the present, but only in the genus Homo, Ungar said.

"I can't think of another behavior, other than chewing, that leaves its record on the teeth of such a broad range of members of our genus, Homo," he said. "It is a behavior unique to our genus."

This behavior is not seen in modern-day apes, Ungar said, although chimpanzees have been recorded using stick-like tools in other ways.

Ungar believes that toothpick use became common about the same time meat turned up in the diet of early hominids. Scientists find evidence of pre-historic meat eaters through the sudden appearance of cut marks on animal bones in the archaeological record.

This is one of the first lines of evidence from the hominid fossil record that shows our genus consuming significant amounts of meat in the ancient past, Ungar said.

"Teeth are not well designed for eating meat, so our early ancestors had to use toothpicks," Ungar said.

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Contacts
Peter Ungar, associate professor, anthropology, (479) 575-6361, pungar@comp.uark.edu

Melissa Blouin, science and research communications manager, (479) 575-3033, blouin@comp.uark.edu

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