People started growing cannabis 12,000 years ago – for food, fiber, and probably to get high

A new study traced the origins of cannabis farming in East Asia to nearly 12,000 years ago. During this time, cannabis was likely a multipurpose crop – farmers only started growing different strains for fiber or drug production until 4,000 years ago.

Landraces of cannabis in Qinghai Province, central China. Photo credit: Guangpeng Ren.

Although little research has been done on cannabis for legal reasons, it is one of the first plants to be domesticated by humans. Archaeological studies have found traces of cannabis in various cultures over the centuries, but when and where exactly cannabis was domesticated was still unclear.

Many botanists believed the plant originated in Central Asia, but a new study shows that East Asia (including parts of China) is the origin of domesticated cannabis.

A research team was led by Luca Fumagalli from the University of Lausanne and included scientists from Great Britain, China, India, Pakistan, Qatar and Switzerland. The researchers compared and analyzed 110 entire genomes of different plants, from wild plants and land races to historic varieties and modern hybrids.

They concluded that the ancient domestication of cannabis plants occurred around 12,000 years ago in what is known as the Neolithic Age, and that the plants likely had multiple uses.

“We show that Cannabis sativa was first domesticated in East Asia in the early Neolithic and that all current hemp and drug varieties deviated from an ancestral gene pool that is currently represented in China by wild plants and land races,” the study says.

“Our genomic dating suggests that the early domesticated ancestors of hemp and drug species differed from basal cannabis [around 12,000 years ago] This suggests that the species was domesticated as early as the early Neolithic, ”the study adds. The results contradict a popular theory about the origin of the plant, the researchers add.

“Contrary to popular belief that cannabis is associated with a Central Asian center of plant domestication, our findings with a single origin of cannabis sativa domesticated in East Asia are consistent with early archaeological evidence.”

When a study can put you in jail

Cannabis grown for drugs. Photo credit: Esteban Lopez.

It’s hard to study cannabis for any reason. You can’t just walk around picking or buying plants, the chances are that this will get you into trouble. To make matters even more difficult, if you want to see where a domesticated plant came from, you’ll need to collect samples from different parts of the world – which is even more likely to get you in trouble.

So, for decades, researchers studied indirect evidence. Most of the cannabis strains appear to have originated in Central Asia, and several cultures in this region have used cannabis for thousands of years, so this seems a likely place of origin. It’s a good guess, but not entirely true.

Cannabis grows almost everywhere – that’s why it’s called “weeds” – and just because people in Central Asia were quick to adopt the plant doesn’t necessarily mean they were the first to grow it.

After overcoming legal and logistical hurdles, Fumagalli was able to collect around 80 different types of cannabis plants, either grown by farmers or grown in the wild. They also included 30 previously sequenced genomes in the analysis.

In doing so, they established that the likely ancestor of modern day cannabis (the original wild plant that was domesticated) is likely extinct. However, his closest relatives survive in parts of northwest China. This fits very well with existing archaeological evidence showing evidence of hemp string markings around 12,000 years ago. In particular, it seems to fit in with a 2016 study by other scientists that said the earliest cannabis records were mostly from China and Japan.

The early domestication of cannabis in the Neolithic could be a big deal. Cannabis is not exactly a food crop. While you can use it to make oil and the seeds can be consumed, its main uses are for fiber and intoxication. When archaeologists look at a population that domesticated a crop, they usually think of food as a priority – but this suggests that the Neolithic peoples had other priorities as well. Or, to put it simply, cannabis was a multi-purpose plant.

Diversification of plants

The team also identified the genetic changes farmers brought about through selective breeding over the centuries. They found that around 4,000 years ago, farmers began to focus either on plants that would produce fiber or on plants that are better suited for making medicines.

For example, cannabis strains bred for fiber production have mutations that inhibit branching, causing them to grow larger and produce more fiber. Meanwhile, strains bred for drug production have mutations that promote branching and reduce vertical growth. This results in shorter plants that produce more flowers. In addition, plants grown for drug production also have mutations that increase the production of tetrahydrocannabinol (THC).

For millennia, hemp (the cannabis grown for fiber) has been an important crop. Clothing, ropes, and various other products used hemp fiber, but the advent of modern metalworking and modern synthetic fibers (like nylon) led to its demise and the once popular plant was almost forgotten. Until recently.

A modern cannabis greenhouse. Photo credit: Richard T.

Recently we have seen a resurgence in interest in cannabis, both for sustainable fiber production and for medicinal and recreational uses. As more countries decriminalize the possession and growth of cannabis, the plant could make a comeback – and this is great news for researchers interested in studying its origins.

While this study offers unprecedented insight into the history of cannabis evolution, it is still a relatively small sample size. It’s hard to find wild specimens – and wild specimens you find today aren’t actually wild, just cultivated varieties that have escaped and are now wild. In addition, even varieties can be difficult to access.

Perhaps as society tends to consider cannabis, researchers can access more resources about it. By studying their genomic history, scientists can also provide valuable insight into the desired functional properties of plants and help breeders develop better varieties for both medicine and other uses.

The study was published in Science Advances.

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