Two ceramic smoking-pipe bowls, excavated in Lalibela Cave, Begemeder Province, Ethiopia, were radiocarbon dated to 1320 ±2 80 A.D. A modified thin-layer chromatographic technique, applied to the pipe residues, yields positive tests for cannabis-derived compounds. Long-lived cannabinoids, produced by the heat of smoking from short-lived psychoactive ingredients in cannabis, makes identification...
