The chewing breaks down the nut and mixes it with the lime, releasing arecoline more rapidly and fully.

The distinctive bright red saliva produced by the lime reaction is one of the most visible markers of betel quid use in populations where it is common.

The ancient Sulawesi foragers were apparently doing something different.

They were not producing the betel quid — they did not have slaked lime, and the dental wear pattern is inconsistent with chewing in the way modern betel quid users chew.

The rounded grooves in the ancient teeth are specifically produced by holding a round, hard object in the back of the mouth against the molar — not by the grinding and crushing action of chewing.