Around 10,000 to 12,000 years ago: The appearance of cannabis in early Chinese contexts, though the specific use as a psychoactive versus fiber or food is debated for the earliest periods.

Around 5,700 years ago: Chemical evidence of mescaline in peyote associated with forager contexts in the American Southwest.

Around 3,500 years ago: The earliest solid evidence of betel nut use, from Bronze Age contexts in Thailand.

Each of these data points was surrounded by discussion of whether even older use was likely and simply not preserved in the archaeological record, or whether the specific dates reflected real thresholds in human behavior.

The general view was that the archaeological record was biased toward underrepresentation — that drug use was probably older than the oldest evidence, but the evidence was hard to preserve and hard to detect.