Metabolomic analysis of 18th–19th pipes from the kingdom of Dahomey (actual Benin) indicates smoking of caffeine-bearing plants

Increasingly, molecular chemistry and pharmacology are complementing classical studies in the field of archaeology. In this case, we present the results of the chemical study of pipe residues found in the context of an archaeological mission (AROMA mission: Archaeology of the Exercise of Royal and Magico-Religious Power) in the royal palaces of Abomey (Benin), dating from the 17th-19th century. The search for many products was carried out (mainly tobacco, cannabis) but surprisingly only highlighted the presence of caffeine residues. This result is discussed and compared with field notions and in particular with ethnological surveys where coffee was consumed in the old way, smoked in a pipe (peripheral part or shell, and not the bean itself or the leaves).