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Human dental hygiene may be 1.8-million-year old practice

 Posted: 2:00 AM October 09, 2013

LOS ANGELES — Say what you will about early Pleistocene man, he sure liked to keep his teeth clean — or at least as clean as he could get them with a toothpick.

In a study published recently in the journal PNAS, authors presented new evidence of "habitual use" of toothpicks by early man 1.8 million years ago.

After examining a handful of fossilized jawbones and teeth unearthed in the Caucusus country of Georgia, researchers suggested that one mandible in particular, D2735, belonged to an inveterate tooth-picker.

Citing a series of horizontal grooves left on the surface of one molar, as well as a gap between the tooth and jawbone, lead author Ann Margvelashvili, a paleoanthropologist at the University of Zurich, wrote that the habit likely caused harm to the picker's gums.

"Toothpicking in this individual likely served to remove nutritional leftovers," Margvelashvili and her colleagues wrote. "But it caused visible damage."

The study's authors say there is ample evidence of toothpicking in mid- to late-Pleistocene hominins, but D2735 suggests the practice of "regular dental grooming" began even earlier.

The mandibles examined by the researchers are part of a larger collection of skulls and other artifacts that were unearthed in the small town of Dmanisi over the last two decades.

Paleoanthropologists have argued over just how to classify these extinct hominins. Currently, they are regarded as a subset of Homo erectus.

One of the challenges of labeling the fossils has been the wide diversity of jawbone shapes. In their paper, the study's authors described how wearing of the teeth will alter the shape of the jaw over time.

The fact that some jaws showed extreme wear, or near complete tooth loss, suggested that these early hominins were able to process their food.

One individual had lost all functional teeth, yet the condition of the jawbone suggested that he had lived for several years in that condition.

"This suggests that behavioral compensatory strategies such as tool-mediated preparation of soft food might have played a crucial role in extending the life expectancy of hominins," the authors wrote.

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