We all have our favorite place to purchase cannabis supplies — online, a local dispensary, delivery service, etc. — but where did it originate from? Who were the first people to cultivate cannabis? How long ago did they first do it?
Most botanists believed that it was first domesticated in the eastern part of Central Asia, where wild varieties of the plant are widespread.
A new study published in Science Advances suggests that East Asia is the most likely source.
Genetic sequencing for this latest study suggests that the species has a “single domestication origin” in East Asia. The study suggests all existing strains of the plant come from an “ancestral gene pool” represented by varieties growing in China today.
By sequencing genetic samples of the plant, they found that the species had most likely been domesticated about 12,000 years ago during the early Neolithic period. They said their conclusion was supported by pottery and other archaeological evidence from the same period that was discovered in present-day China, Japan, and Taiwan. The plant was thought to be a “primarily multipurpose crop” grown for fiber and medicinal uses.
The study was led by Ren Guangpeng, a botanist at Lanzhou University in the western Chinese province of Gansu. Dr. Ren said that the finding could help with current efforts in the country to breed new types of hemp.
Dr. Ren and his colleagues believe that farmers began breeding the plant specifically for its mind-altering properties about 4,000 years ago, as cannabis began to spread into Europe and the Middle East.
Michael Purugganan, a professor of biology at New York University who read the study, said the usual assumption about early humans was that they domesticated plants for food. He’s skeptical about conclusions that the plant was developed for fiber or drug use 12,000 years ago. Archaeological evidence shows the consistent use of cannabis for those purposes began about 7,500 years ago.
“That seems to be the most pressing problem for humans then: How to get food,” said Professor Purugganan. “The suggestion that even early on they were also very concerned with fiber and even intoxicants …would bring to question what were the priorities of these Neolithic societies.”
As hemp became less functional (textiles, food, oilseed) in the 20th century, it became more recreational. But there are still “large gaps” in knowledge about its domestication history in large part because the plant is illegal in many countries.
“Although additional sampling of feral plants in these key geographical areas is still needed, our results, which are based on very broad sampling already, would suggest that pure wild progenitors of C. sativa have gone extinct,” Dr. Ren and his colleagues wrote.
Catherine Rushworth, a postdoctoral researcher at the University of Minnesota who studies plant evolution, explained it can be difficult to understand precisely how plant species are domesticated in the first place. Scientists can make some basic predictions about how a given plant species will diverge in nature, but such predictions “go out the window” when natural selection is driven by humans.
“We might think that species would diverge when they’re adapting to different habitats, or to different pollinators,” she said. “But people are often the pollinators and people have created those habitats.”
The authors of the study concluded, “Although additional sampling of feral plants in these key geographical areas is still needed, our results, which are based on very broad sampling already, would suggest that pure wild progenitors of C. sativa have gone extinct.”