No. 71: Sep-Oct 1990
Some mysterious cultural practice of ancient people all over the world resulted in curious grooves on tooth surfaces. The grooves occur near the cementoenamel junction, mostly on molars and premolars, and usually on males. The diameter of the channel between adjacent teeth varies from 1-4 millimeters. (See SF#61 for an earlier item on the subject.)
Proposed solutions to this riddle range from bacterial attack, to gritty saliva propelled through the teeth, to the overenthusiastic use of bone toothpicks. But Australian aborigines have provided a more convincing explanation. When the aborigines want, thin, strong cords for fashioning spears and spearthrowers, they take a pliable, thinned, kangaroo sinew, pull it down between their molars like dental floss and begin "stripping" it, by pulling it back and forth. They get their thin cords this way but also grooved teeth. (Eckhardt, Robert B.; 'The Solution for Teething Problems," Nature, 345: 578, 1990.)
Comment. Unless someone comes up with a fatal objection to this theory, we must de-anomalize the grooved-teeth phenomenon.