The study combined three distinct lines of evidence:

First, dental wear analysis.

Vlok examined the distinctive rounded grooves in the teeth of both individuals and documented them as a previously unrecognized form of dental pathology.

The grooves were not cavities.

They were not the wear patterns typical of processing tough plant foods.

They were smooth, rounded, hollowed-out channels that ran around the tooth at a specific angle — the angle consistent with holding a round object in the back of the mouth, against the molar, for extended periods.

The size of the objects that would produce this pattern: 10 to 20 millimeters in diameter.