Cannabis utilization and diffusion patterns in prehistoric Europe: a critical analysis of archaeological evidence

Archaeological evidence of Cannabis sativa is comprised of textiles, cordage, fibre and seeds, or pottery impressions of those materials, as well as pseudoliths and phytoliths (pollen is not addressed here). Previous summaries of this evidence connect hemp with Bronze and Iron Age cultures in Europe. This study improves upon earlier summaries by: (1) accessing a larger database; (2) relying on original studies instead of secondary sources; (3) stratifying evidence by its relative robustness or validity. We coupled digital text-searching engines with internet archives of machine-readable texts, augmented by citation tracking of retrieved articles. The database was large, so we limited retrieval to studies that predated 27 bce for west-central Europe, and pre-ce 400 for eastern Europe. Validity of evidence was scaled, from less robust (e.g., pottery impressions of fibre) to more robust (e.g. microscopic analysis of seeds). Archaeological sites were mapped using ArcGIS 10.3. The search retrieved 136 studies, a yield four-fold greater than previous summaries when parsed to our geographic/time constraints. Only 12.5% of studies came from secondary literature. No robust evidence supports claims of Neolithic hemp usage. One Copper Age site in southeastern Europe shows robust evidence (from the Gumelniţa-Varna culture). More robust evidence appears during the Bronze Age in southeastern Europe (Yamnaya and Catacomb cultures). An Iron Age steppe culture, the Scythians, likely introduced hemp cultivation to Celtic, Slavic and Finno-Ugric cultures. The results correlate with a recent palynology study of fossil pollen in Europe. We discuss possible autochthonous domestication of Cannabis in Europe.