In a paper that is about to be published in the journal Perspectives in Plant Ecology, Evolution and Systematics, the origin, early dispersal, human domestication and anthropogenic diffusion of Cannabis are reviewed and discussed.
According to DNA phylogenies, Cannabis diverged from its sister genus Humulus between the mid-Oligocene (28 Ma) and the early Miocene (21Ma), but the first fossil records date from the early Miocene (20 Ma). Then, this plant expanded from its center of origin (the NE Tibetan Plateau) to Europe and eastern Asia between the Miocene and the Pliocene, before the onset of human evolution.
During the Pleistocene (the last 2.6 Ma), the European and Asian cannabis populations became geographically isolated due to the glacial-interglacial recurrence, which led to the evolutionary origin of the ancestors of the present subspecies – C. sativa subsp. sativa in Europe and C. sativa subsp. indica in Asia. The first is the putative hemp ancestor (PHA) while the second is the putative drug ancestor (PDA).
Human domestication of Cannabis (PDA) took place in E Asia ca. 12,000 ago (early Neolithic), which situates this plant among the earliest human domesticates. The possibility of another center of domestication in the Caucasus region (PHA) is also considered.
Cannabis was transported outside Eurasia in its cultivated forms and reached Africa (drug biotypes) only after 2000 yr BP. The diffusion to the Americas (hemp and drug biotypes) did not occur until 1545 CE and, by 1945 CE, all Cannabis biotypes were already widespread worldwide.
Rull, V. 2022. Origin, early expansion, domestication and anthropogenic diffusion of Cannabis, with emphasis on Europe and the Iberian Peninsula. Prespectives in Plant Ecology, Evolution and Systematics, 55: 125670, doi 10.1016/j.ppees.2022.125670.