A study by a team from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing, in which the Spanish researcher of Dental Anthropology from the National Center for Research on Human Evolution (CENIEH) Laura Martín-Francés has collaborated, sheds light on the earliest evidence of toothpick marks on the teeth of Middle Pleistocene hominids in eastern Asia.
According to the researchers, the marks could be due to the action of removing food debris from the teeth .
The article, published in the journal Quaternary International, explains how the interproximal surfaces of fossil Homo erectus teeth discovered in the 1980s at Yiyuan, a Chinese site in Shandong province, have been studied under the microscope, and highlights the toothpick marks visible on five of the seven teeth analyzed, belonging to three individuals.
The precision provided by the binocular microscope and scanning electron microscopy reveals wear on crowns and roots of teeth, in the form of fine grooves or even deep grooves. The location, morphology and dimension of these signs of wear are similar to that produced by the usual use of toothpicks.
In addition, the type of marks on the Yiyuan teeth, the oldest in Asia, coincide with the toothpick marks already identified in other species such as Homo habilis, from the African Plio-Pleistocene; Homo heidelbergensis, Middle Pleistocene Europe; and Homo neanderthalensis, from the European Upper Pleistocene.
In a previous study by Laura Martín-Francés on the oldest toothpick marks in Europe, the dental pathologies of a 1.2 million-year-old hominid found in the Sima del Elefante, in Atapuerca, were analyzed.
Possible causes of these toothpick marks were oral hygiene, the removal of food trapped between the teeth, relief due to pain or pathology or a simple habit. In the case of Yiyuan, the marks are due to the extraction of food debris between the teeth, because they are healthy and do not present pathologies.
