from The Dallas Morning News: "Parallel grooves etched in the enamel of an ancient tooth found in [Tanzania] may have come from a toothpick wedged between two teeth to clean out stuck food. The toothpick must have been sharp - perhaps a piece of bone or a gritty stick ..." "A diet of meat not only sticks to your bones, it also sticks to your teeth. Peter Ungar, a University of Arkansas anthroplogist who found the grooves, said the the earliest toothpick use may have coincided with the addition of meat to the diet of early humans."