Likely originating in Central Asia, the cannabis plant may have been one of the first plants cultivated by humans. In addition to its psychoactive charms, cannabis gave early growers nutritious seeds to eat and useful fibers for rope.

Our ancestors even discovered some of the medicinal benefits of cannabis. The ancient Chinese deity Shennong, or “God Farmer,” recommended that cultivators grow “hemp elixir” to treat the sick. Cannabis has a particularly rich history in India, where it has been used for thousands of years as a spiritual aid.

Even as great societies of metal and stone formed, cannabis remained an indispensable crop. Ancient Rome, for instance, wouldn’t have been the sea power it was without using strong hemp sails and ropes. The British and Spanish, too, powered their world-spanning empires with hemp riggings. Our first president, George Washington, was even known to grow cannabis.

As we mentioned, early civilizations were quick to discover the psychoactive effects of marijuana. Mexico, in particular, emerged as a major cultivator of psychoactive strains in the early 1900s, and that cannabis wafted over the border into the United States. Then, in 1937, the US passed the Marijuana Tax Act, which effectively criminalized the drug. And in 1970 the Controlled Substances Act branded cannabis as a Schedule I drug, increasing the severity of punishments for being found with it.

As with the prohibition of alcohol, banning the consumption of cannabis just drove the drug underground. Which brings us to the legend of Northern California, a longstanding mecca of cannabis production. Over the last few decades, cultivators have hidden themselves in the wildlands, producing nearly 75 percent of the domestically grown cannabis consumed in the US. Growers here have selected plant generation after plant generation for high THC content, to the point where you can now regularly find flower with 25, even 30 percent THC, whereas a few decades ago the average was around 5 percent.

While Northern California’s growers were proving themselves masters of cannabis cultivation, the plant remained—and, to a large degree, still remains—mysterious, because, until recently, it has been extremely difficult for researchers to study a Schedule I drug. Until 2016, the DEA claimed a monopoly on the official supply of research cannabis, licensing a single farm at the University of Mississippi that produced an odd strain of marijuana that looks nothing like what’s out on the market.

That regulatory wall, though, is crumbling, and science is rejoicing.

CANNABIS GLOSSARY

Cannabinoids
Compounds that bind to receptors in the human body’s endocannabinoid system, producing both psychoactive effects, in the case of THC, and non-psychoactive effects, in the case of CBD.

Chemotype
The distinct chemical makeup of an individual cannabis plant, which varies both because of genetics and because of environmental factors. Researchers are now experimenting with how to tweak light and soil composition to express or suppress certain chemical components.

Hemp
A variety of the cannabis plant that contains vanishingly small amounts of THC. Its’ extremely strong fibers have many uses, even today.

Marinol
A synthetic form of THC used to treat ailments like nausea and low appetite. Its’ cousin is Sativex, which also includes a dose of CBD that may help offset the psychoactive effects of THC.

Terpenes
A family of compounds that give cannabis its unique smell. However, terpenes are not limited to the cannabis plant—citrus plants have them, as well. Many plants use these volatile compounds to ward off insects.

The Entourage Effect
The anecdotal, though increasingly data-backed, theory that different compounds in cannabis contribute to the body high that the plant produces. Research shows, for instance, that while THC alone can lead to paranoia, pairing it with CBD tends to attenuate the psychoactivity.