Cannabis’ medicinal qualities were exploited before the Christian era in Asia, mainly in India.
In most ancient cultures, “getting high” was not the main use for the plant. Hemp fiber was valued for making clothes and other textiles, and its seeds were used for food and oil. The types of plant used for these purposes had very low amounts of THC, the chemical that causes intoxication.
Yet, the ancients did know about the plant’s mind-altering properties and may have bred varieties for this purpose as well. The oldest evidence of this is the remains of burned cannabis seeds that have been found in graves of shamans—religious leaders and healers—in China and Siberia from around 500 BC.
The oldest evidence of marijuana being used recreationally comes from an ancient Greek historian named Herodotus (484–425 BC). He described how people of a Eurasian society called the Scythians inhaled the vapor of cannabis seeds and flowers thrown on heated rocks. It might have not sounded that appealing to his Greek readers, though, who much preferred to get “high” on wine, as did the Romans later.
The first drug to rival alcohol for popularity in Europe was tobacco, imported from America in the late 1500s. Coffee followed about a century later, imported from Africa. And although Europeans cultivated hemp and occasionally smoked cannabis, its popularity didn’t match that of alcohol, tobacco, and coffee.
Unlike in Europe, however, cannabis (in the concentrated form called hashish) did become widely used in the Middle East and South Asia after about 800 AD. The reason has to do with the spread of Islam. The Koran strictly forbade Muslims from drinking alcohol or partaking in other intoxicating substances, but it did not specifically mention cannabis.
Beginning in the 19th century, use of cannabis in Western medicine grew along with the availability of different extracts or tinctures. However, medical use decreased in the first decades of the 20th century due to inconsistent production of plant quality and potencies. Eventually, producers identified beneficial cannabis components and purer constituents in the 1960s. Scientific interest was renewed in the 1990’s with the description of cannabinoid receptors and the identification of an endogenous cannabinoid system in the brain. Since treatment effectiveness and safety started to be scientifically proven, a new and more consistent variety of cannabis derivatives proved effective in more medical settings.
Jefferson, along with George Washington and Benjamin Franklin, did grow hemp on their farms, as did most people who owned land, but there’s no direct evidence they ever smoked it. The amount of the psychoactive (mind-altering) chemical THC in most hemp at the time was probably too low anyway to become intoxicated from it. When Colonial Americans smoked anything, it was mainly tobacco—the drug that was also a big part of America’s economy during those times.