A new analysis of primate teeth suggests that grooves once attributed to ancient tooth-picking may form naturally instead. Researchers also found no signs of a common modern dental issue in wild primates.
Grooves on ancient human teeth have long been interpreted as evidence of deliberate tooth-picking with sticks or fibers. A study published in 2025 in the American Journal of Biological Anthropology examined more than 500 teeth from 27 primate species, both living and extinct. The team, led by Ian Towle and Luca Fiorenza, found similar grooves in wild primates. These marks matched classic descriptions of so-called toothpick grooves, including fine parallel scratches. No abfraction lesions appeared in any of the wild specimens. Such wedge-shaped notches near the gumline are common in modern humans and linked to forceful brushing or acidic drinks. The findings indicate that some dental problems may be unique to human lifestyles today. They also urge caution when interpreting fossil marks as signs of tool use.