Cannabis is indigenous to Europe and cultivation began during the Copper or Bronze age: a probabilistic synthesis of fossil pollen studies

John M. McPartland · Geoffrey W. Guy · William Hegman

Vegetation History and Archaeobotany, 2018, 27, 635–648

Doi : 10.1007/s00334-018-0678-7

 

Abstract

Conventional wisdom states Cannabis sativa originated in Asia and its dispersal to Europe depended upon human transport. Various Neolithic or Bronze age groups have been named as pioneer cultivators. These theses were tested by examining fossil pollen studies (FPSs), obtained from the European Pollen Database. Many FPSs report Cannabis or Humulus (C/H) with collective names (e.g. Cannabis/Humulus or Cannabaceae). To dissect these aggregate data, we used ecological proxies to differentiate C/H pollen, as follows: unknown C/H pollen that appeared in a pollen assemblage suggestive of steppe (Poaceae, Artemisia, Chenopodiaceae) we interpreted as wild-type Cannabis. C/H pollen in a mesophytic forest assemblage (Alnus, Salix, Populus) we interpreted as Humulus. C/H pollen curves that upsurged and appeared de novo alongside crop pollen grains we interpreted as cultivated hemp. FPSs were mapped and compared to the territories of archaeological cultures. We analysed 479 FPSs from the Holocene/ Late Glacial, plus 36 FPSs from older strata. The results showed C/H pollen consistent with wild-type C. sativa in steppe and dry tundra landscapes throughout Europe during the early Holocene, Late Glacial, and previous glaciations. During the warm and wet Holocene Climactic Optimum, forests replaced steppe, and Humulus dominated. Cannabis retreated to steppe refugia. C/H pollen consistent with cultivated hemp first appeared in the Pontic-Caspian steppe refugium. GIS mapping linked cultivation with the Copper age Varna/Gumelniţa culture, and the Bronze age Yamnaya and Terramara cultures. An Iron age steppe culture, the Scythians, likely introduced hemp cultivation to Celtic and Proto-Slavic cultures.

Keywords : Cannabis sativa · Humulus lupulus · European Pollen Database · Europe · GIS · Pleistocene · Holocene

 

Introduction

Linnaeus (1737) knew Cannabis sativa as a cultivated plant in Europe, so he assumed its centre of origin (CoO) was elsewhere. He suggested a CoO in India Orientali (encompassing the Indian subcontinent, southeastern Asia, and the Malay Archipelago), Japonia (Japan), or Malabaria (the Malabar coast of southwest India). Most scholars concur with de Candolle (1883) who offered Central Asia as the CoO of C. sativa. He collated linguistic, historical, archaeological, and palaeontological data, as well as “in what country it grows spontaneously and without the help of man”. He proposed that C. sativa expanded to Europe under the aegis of human transport around 1500 bce, and he implicated the Scythians.

Some botanists placed the CoO of C. sativa in Europe (Thiébault de Berneaud 1835; Keppen 1886), or a CoO spanning Asia and Europe (Herder 1892; Vavilov 1926). indica. He suggested that C. sativa grew croît naturellement in Persia and presque naturalisée in Europe, whereas C. indica originated in India. Many botanists treat these taxa as subspecies, C. sativa ssp. sativa, and C. sativa ssp. indica (Small and Cronquist 1976). Winterschmidt (1818) recognized two species, C. sativa and C. chinensis, with their CoOs in Russia and Ostindien, respectively.

De Candolle limited his palaeontological evidence to print fossils (impressions of leaves or fruits in rocks), and not fossil pollen (accurately, subfossil pollen). Reports of print fossils of C. sativa have not been convincing (four reported world-wide), with one exception (Palamarev 1982). Conversely, hundreds of fossil pollen studies (FPSs) across Eurasia have identified Cannabis pollen. Researchers have utilized this database to track the cultivation history of C. sativa in Europe and Asia. Dörfler (1990) analysed 77 European FPSs conducted by himself and others. He concluded that hemp cultivation began in west-central Europe by the Iron age. Clarke and Merlin (2013) reviewed 133 European FPSs. They concluded that C. sativa diffused from Asia to Europe during the Bronze age. Long et al. (2017) synthesized 46 FPSs in their pan-Eurasian study. They also concluded that C. sativa diffused from Asia to Europe during the Bronze age.

All three meta-analyses (Dörfler, Clarke and Merlin, Long et al.) corroborated FPS data with archaeo-botanical evidence—seed, fiber, cordage, textiles, and pottery impressions or pseudoliths of the same. We have also examined archaeobotanical evidence, published separately (McPartland and Hegman 2017). Robust archaeobotanical evidence identified the Bronze age Yamnaya culture as an early adopter of C. sativa, in southeastern Europe.

The purpose of this study is to revisit European FPSs, by accessing an expanded database, and using a different pollen identification method. Unlike previous studies (Dörfler 1990; Clarke and Merlin 2013; Long et al. 2017), we included FPSs that analysed strata anterior to the Holocene epoch. As de Candolle (1883) stated, “conditions anterior to our epoch determined the greater number of the facts of the actual distribution of plants”. Examining pollen from earlier epochs will address the question of C. sativa endemicity in Europe, prior to its transport by humans.

The previous three meta-analyses utilized pollen grain morphology for pollen identification. Dörfler (1990) encountered problems separating Cannabis from Humulus pollen. Many palynologists, confronted with the morphological similarities between Cannabis and Humulus, resort to collective names, e.g. Cannabis/Humulus, or Cannabaceae. Hereafter we abbreviate these lumped data as C–H pollen. Clarke and Merlin (2013) were flummoxed by FPSs that lumped data as C–H pollen; they understood the complexities regarding grain morphology (Fleming and Clarke 1998). Long et al. (2017) resolved the C–H dilemma by limiting FPSs to studies that explicitly identified pollen as Cannabis—a strategy that excluded a lot of C–H data.

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