Peter Ungar, Associate Professor of Anthropology at the University of Arkansas, claims to have found evidence of toothpick use at Olduvai Gorge. Scanning electron analysis of a 1.8 million year old tooth discovered by the colleagues of Mary Leakey found tiny parallel lines repeated along the edges of the tooth. In his opinion, the size, shape and orientation of the grooves are evidence of someone trying to shove something narrow into a small space between their teeth.
Ungar presented his findings at the American Association of Physical Anthropology in April, 2000.