As the once-vilified drug becomes more accepted, researchers around the world are trying to understand how it works and how it might fight disease.
Credit: Lynn Johnson/National Geographic

There’s nothing new about cannabis, of course. It’s been around humankind pretty much forever.

In Siberia charred seeds have been found inside burial mounds dating back to 3000 B.C. The Chinese were using cannabis as a medicine thousands of years ago. Marijuana is deeply American too—as American as George Washington, who grew hemp at Mount Vernon. For most of the country’s history, cannabis was legal, commonly found in tinctures and extracts.

Then came Reefer Madness. Marijuana, the Assassin of Youth. The Killer Weed. The Gateway Drug. For nearly 70 years the plant went into hiding, and medical research largely stopped. In 1970 the federal government made it even harder to study marijuana, classifying it as a Schedule I drug—a dangerous substance with no […]