Cannabis Smoking in 13th-14th Century Ethiopia: Chemical Evidence

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 possible. The origins and spread of Cannabis sativa are obscure, although the plant has achieved worldwide distribution, and is commonly known under such names as bhang, ganja, dagga, hemp, marijuana, etc. The psychoactive properties especially of its tropical varieties are well-known as they have apparently been since the 3rd millennium B.C. The plant is mentioned in a 2737 B.C. pharmacological treatise attributed to the Chinese emperor Shen-Nung (Merlin 1972). Another possible reference occurs in Vedic texts from India around 2000-l400 B.C., while Herodotus gives a clear description of the Scythian practice of throwing hemp seeds on hot rocks in a confined space. By 950 A.D. the use of cannabis was well-established in Arabia; Marco Polo's account of the alleged hashish-related assassin's cult of Hasan-ibn-al-Sabbah (11th century) is also well-known, if not necessarily accurate. We now have chemical evidence that the plant was smoked in Ethiopia in the l3th-l4th century A.D. According to Vavilov's phytogeographic postulates, the site of species formation of Cannabis sativa was in central or Southeast Asia; the plant was probably domesticated in the same region. The cultigen is of the same species, while a more strongly psychoactive form has been named Cannabis indica; the latter may or may not be a separate species.' Since the same psychoactive compounds are involved in both cases, the differences can be ignored here. The main psychoactive constituent is tetrahydrocannabinol (THC); this, along with cannabinol and cannabidiol, is the substance commonly tested for in the chemical identification of cannabis (Turk et al. 1969). They occur naturally only in the cannabis plant (THC has been produced synthetically). All three compounds degrade at least partially when burned (as in smoking), and also deteriorate rapidly with time. These attributes provide difficulties when testing for evidence of cannabis use in residues from ancient smoking pipes. Two ceramic pipe bowls, excavated by J. C. Dombrowski (1971) at the site of Lalibela Cave in the Begemeder Province of Ethiopia (near Lake Tana), were tested for the presence of cannabinolic compounds. The pipes came from level 2 of the cave, with an associated