A team of researchers just examined 110 different marijuana genomes to figure out the origin of the plant. Their findings put the genesis of Cannabis sativa in northwest China.
The research combined 82 newly sourced genomes with 28 publicly available genomes for hemp and drug-type cannabis plants. From that extensive genetic repository, the team sorted the plants into four different groupings: Basal cannabis, which includes 16 feral plants (ancient domesticated plants) and naturally cultivated varieties; hemp varieties; feral drug-type cannabis; and cultivated drug-type cannabis. The team determined the basal cannabis group to be the most original cannabis, from which the latter groups derived, all in the last 12,000 years. The team’s research is published today in Science Advances.
“We unraveled the geographic origin of the cultivation of cannabis (East Asia), the date (early Neolithic), and the presence of a cannabis genetic lineage unknown to date, distinct from the one that gave rise to the hemp and marijuana varieties distributed worldwide, and probably still similar to the early domesticated common ancestor of all these lineages,” said study co-author Luca Fumagalli, a conservation geneticist at the University of Lausanne in Switzerland, in an email. “We also found that the two genes involved in the synthesis of CBD and THC were alternately lost during strong selection for either psychoactive properties or fiber production, respectively.”
Though previously a matter of debate, cannabis researchers have largely reached consensus that cannabis is comprised of just one species—Cannabis sativa—and this research corroborates that idea. So if you hear someone refer to indica, they’re still talking about a Cannabis sativa plant.
The team determined that the wild progenitors of cannabis have gone extinct, hence the sole presence of cultivated and feral varieties. This idea had been proposed previously, but the expansiveness of the recent research corroborates earlier findings. One previous study focused on ancient cannabis pollen and the related Humulus plant (you may know it as hops, different types of which are added to beer), which are found across Asia dating back tens of millions of years. But that study merely dated the pollen, rather than tracking how different strains of plants the around the world interrelate and crop up at different times.
“Through analyzing the most geographically diverse panel of Cannabis sativa genomes to date, Ren et al. have conclusively circumscribed this globally distributed plant as belonging to a single species, Cannabis sativa,” said Ryan Lynch, an ecologist and hemp researcher who was not affiliated with the recent paper, in an email. “If confirmed, these are important findings that require both further study and immediate conservation efforts to preserve the remaining Cannabis sativa genetic diversity, which is at risk of being lost forever due to the general lack of funding and effort by scientific and germplasm preservation agencies.”
The team identified specific genes as having been selected for cultivation. Those genes were connected to the formation of the plant’s branches, the timing of its flowering, the strength of its cell walls, and, perhaps most interesting, the synthesis and potency of cannabinoids in the drug-type plants. Fumagalli said that, in the future, the team would like to compare the cannabinoid content produced by feral and basal plants, “which we predict to be significantly lower than the one produced by hemp- and drug-types.”