It documents the pharmacological mechanism by which the habit was maintained and potentially reinforced through the pain-relief cycle.

It does not document the initial impetus.

Multiple possibilities have been discussed by researchers commenting on the study:

Pain relief for pre-existing toothaches.

Arecoline has analgesic properties — it numbs pain.

A forager with a painful tooth might have discovered, intentionally or by accident, that holding an areca nut against the sore tooth provided temporary relief.

If the nut was already known as a food item or a useful object, trying it against a toothache would have been a natural experiment.

Stimulant effects for hunting and foraging.