Direct evidence for psychoactive cannabis use 2800 years ago

Cannabis is the world's most-used illicit psychoactive plant, yet direct prehistoric evidence for its consumption is rare. In this study, we present the earliest direct evidence of cannabis use: offerings of plant parts and chemical compounds in ancient human hair recovered from a monumental tomb in Siberia. The findings suggest that the plant was used for its psychoactive qualities across Eurasia, where specific wild populations might have had naturally higher active compound levels. We show that the practice of cannabis consumption dates back at least 2800 years, anchoring debates around contemporary usage and informing discussions on cannabis in medicine, public health, law, and industry.