Genetic analysis of over 100 cannabis Sativa genomes has revealed that the plants’ wild ancestors likely came from present-day China. The findings were published in Science Advances by an international team of researchers.
Tracking the history of cannabis domestication has previously been challenging due to legal hurdles in obtaining the plant. While many sources suggest that cannabis originates in Central Asia as many strains grow there, until now, researchers have been unable to conduct genetic studies on the plants to confirm their origins.
Now, however, an international team of researchers collected and sequenced the genomes of 82 different kinds of cannabis plants both from domesticated and wild sources. The samples used for genetic analysis included seeds, leaves, and other plant material from countries including Switzerland, China, Pakistan, India, and Peru.
Together with 28 previously sequenced genomes, they examined each strain for clues about their geographical origins over four years. Whereas previous studies examining cannabis genomes involved thousands of single nucleotide polymorphisms (SNPs), this study included 12 million SNPs. SNPs are single locations in a genome that can contribute to the difference between species.
From their analysis, the researchers found that Cannabis sativa was first domesticated in China around 12,000 years ago. The study also shows that the psychoactive and fibrous versions of cannabis used for recreation and clothing didn’t diverge until 4,000 years ago. This means cannabis domestication began when other agricultural innovations were also being made in China with crops including rice, soybeans, and peaches.
“We thought we would find two main lineages, one with plants for fiber use and then plants developed for cannabinoid production,” says Luca Fumagalli, co-author of the study. “We didn’t expect to find this third independent and basal lineage among the samples from East Asia.”
While this study used the most comprehensive database of genetic samples until now, the researchers note that they did not examine staples from Afghanistan or Russia, two countries known to have vast swathes of wild cannabis. They also note that they only analyzed the genomes of living samples, whereas dried plant materials could shed light on older and rarer varieties.