Cannabis sativaL.

THC works by walking directly into the pocket on CB1 that the body's own signals use. It binds as a partial agonist: per receptor it does not push as hard as a full agonist could, but it binds tightly, lingers far longer than a natural endocannabinoid, and reaches nearly every CB1 at once rather than the handful at one working synapse. The effect is large and diffuse rather than local and self-correcting. That is the high.

CBD's story is genuinely different, and worth resisting the tidy shorthand about calming what THC excites. CBD has only weak direct affinity for CB1; its best-documented action there is as a negative allosteric modulator, and its clearest clinical win, controlling seizures in severe childhood epilepsy, appears not to run through cannabinoid receptors at all. It looks like the sum of many soft, indirect actions rather than one dominant lever.

Long before agriculture had a name, on the steppes and foothills from the Caucasus to the Altai, a wind-pollinated weed struck up a partnership with human beings that would outlast every empire built afterward. It colonized the disturbed, nitrogen-rich ground that gathers wherever people camp and till. Hemp fiber left its imprint on Yangshao pottery in China by the fifth millennium BC.

China keeps the fiber side in its writing: the character for hemp shows two plants drying under a shelter, and the same character doubles as the word for "numb," the plant's other nature hiding inside the script. Its psychoactive use enters the written medical record in the Shennong Bencaojing, and Taoist practice added it to ritual incense by the sixth century.

Westward, Herodotus around 440 BC described the Scythians creeping under felt tents, throwing hemp seed on hot stones, and inhaling the smoke, shouting for joy. Twentieth-century archaeology vindicated him almost exactly: the frozen Pazyryk kurgans of the Altai gave up bronze censers still holding charred hemp seed beside collapsible tent frames, from the fifth to second centuries BC.

India built the longest religious relationship of any culture, with a vocabulary precise by potency: bhang from the leaves, ganja from the flowering tops, charas the hand-rubbed resin. Shiva carries the epithet Lord of Bhang; during Holi and Maha Shivratri devotees still drink bhang as a sacrament, and wandering sadhus have long used it as an aid to renunciation. From Persia the drug-type lineage moved into the Islamic world as hashish, carried by Sufi orders pursuing altered states as a path to the divine.

The plant crossed the Atlantic with colonization, first as fiber: English settlers found hemp already growing in Powhatan Virginia, and by 1619 the House of Burgesses compelled every planter to sow it. It reentered Western medicine in the 1840s through William O'Shaughnessy, who brought preparations back from Calcutta, and through the Paris Club des Hashischins. That medical normalization gave way within a lifetime to prohibition, from the 1937 US Marihuana Tax Act to the 1961 UN Single Convention, and then, slowly, swung back: the Netherlands from 1976, California's 1996 medical law, Uruguay's full legalization in 2013, Canada in 2018.