Origins of Cannabis sativa in Ireland and the Concept of Celtic Hemp: An Interdisciplinary Review

Introduction: Ireland's agriculture has been shaped by Celts, Romano-British Christians, Norse-Vikings, Anglo-Normans, and subsequent migrants. Who introduced hemp (Cannabis sativa) to Hibernia? We addressed this question using historical linguistics, fossil pollen studies (FPSs), archaeological data, and written records.Methods: Data gathering utilized digital resources coupled with citation tracking. Linguistic methods separated cognates (words with shared etymological origins) from loanwords (borrowed from other languages). Cannabis pollen in FPSs was identified using the "ecological proxy" method. Archaeological reports were ranked on a "robustness" scale.Results: Words for "hemp" in Celtic languages are loanwords, not cognates. The Irish word cnaib is first attested in texts written 1060 and 1127-1134 CE. Old Breton coarcholion, corrected to coarch, is attested in a text from the 9th century. Pollen consistent with cultivated Cannabis appears in the Middle Ages, ca. 700 CE, at sites in the vicinity of monasteries. Archaeological finds (hemp seeds and fiber) date to later Norse-Viking and Anglo-Norman sites.Discussion: People of the Hallstatt Culture in Central Europe have long been considered speakers of the "Proto-Celtic" language. The lack of "hemp" cognates means a Proto-Celtic word cannot be reconstructed, which implies that Hallstatt people (with robust archaeological evidence of hemp) did not speak Proto-Celtic. Cnaib is absent in Old Irish glossaries, epics, and mythologies (600-900 CE). FPS data suggest that the onset of hemp cultivation correlated-chronologically and spatially-with the founding of Romano-British monasteries. Irish cnaib was likely borrowed from Clerical Latin canapis or canabus.