Ancient tooth grooves: take your pick.

Ancient tooth grooves: Take your pick

In 1911, a French anthropologist observed unnatural grooves on the teeth of several Neanderthal fossils. Similar grooves have been noted since in a variety of fossil teeth, including those belonging to Homo habilis around 1.84 million years ago, H. erectus, early H. sapiens, Stone Age and Bronze Age people and prehistoric North American Indians. Many researchers believe the grooves resulted from the repeated use of wood or bone toothpickes, but they differ on the reasons for their use. Some see the repetitive probing as a cultural behavior without practical use, while a more common theory holds that tooth-picks were used to eliminate tissue damaged by tooth decay or gum disease and to remove trapped bits of food.

New evidence of grooving in the teeth of human ancestors, reported in the August-October CURRENT ANTHROPOLOGY, supports the cultural explanation. Polished, semicircular grooves in teeth from the skulls of three previously excavated H. sapiens are not associated with tooth decay or excessive tooth wear, says Vincenzo Formicola of the Anthropology and Human Paleontology Institute in Pisa, Italy. The teeth were uncovered at a site dating to between 10,000 and 20,000 years ago. Formicola suggests wooden toothpicks were used in "a largely nonfunctional, unnecessary, stereotyped activity."

Six teeth recently uncovered in the Soviet Union and estimated at between 400,000 and 700,000 years old contain polished grooves much like those described by Formicola, says Christy G. Turner of Arizona State University in Tempe. Soviet anthropolists, who showed Turner the teeth, said they think the teeth belong to H. erectus or early H. sapiens. Again, the teeth show no signs of decay, erosion or pitting. Even if dental problems or heavy tartar accumulation initially stimulated toothpick use, Turner suggests the activity often became a lifelong habit. "As far as can be empirically documented," he says, "the oldest human habit is picking one's teeth."

Robert B. Echkhardt and Andrea L. Piermarini of Pennsylvania State University in University Park report the first evidence of apparent prehistoric toothpick use in South America, based on teeth from a Peruvian site estimated to be 9,525 years old. But causes of grooving in these and other remains are poorly understood, they caution. Eckhardt and Piermarini lean toward explaining toothpick use as a means to deal with dental problems. Studies of modern populations are "sorely needed," they conclude, to determine what cultural practices might produce tooth groovs.