Marijuana has been around for millennia. Its use as a psychoactive drug dates back to at least 2737 B.C., when it was written about in the Book of Drugs by Chinese Emporer Shen Nung. Yet even back then it seemed to be causing a ruckus. Villagers reported that youngsters who took it stopped listening to their elders and engaged in other scandalous behavior. (Hanson et al., 2004)

Selective breeding of marijuana plants over the years have led to many different strains of pot. Walk into a medical marijuana store and you’ll find more variety than a Baskin Robbins, with clever and cutsie names like “Sticky Wicky” or “Rocky Mountain Green.” Yet it appears that all strains of marijuana trace back to a single species of plant that probably originated somewhere in Southeast Asia.

The potency of marijuana today

The main psychoactive ingredient in marijuana is tetrahydrocannabinol, or THC for short. Over the years selective breeding by marijuana cultivators has significantly increased the amount of THC contained in marijuana. “Depending on how the plant is cultivated, the relative proportion of the different types of cannabinoids changes,” says neuropharmacologist Veronica Campbell. “The ‘joints’ that are available now are much stronger in terms of their THC content than those that would have been around when people were thinking of cannabis as being quite a soft drug.” (Douglas-Fields, 2009)

The marijuana available today is around 20-times more potent than that which was on the market in the 1960s and 1970s. (Hanson et al., 2004, p. 379) According to another report released in 2012 by the American Society of Addiction Medicine, the average THC concentration in confiscated marijuana jumped from 3.4 to 8.8 percent just in the years between 1993 and 2008. (Khamsi, 2013) It continues to steadily rise.

Keep in mind that these numbers are only averages, and the THC contained in individual samples can be much higher or lower, depending on the particular breed and how it is harvested. The THC in street pot averages from as little as 0.5% to 11%, but as stated before, has been steadily rising. The THC content can range from 7.5% to as high as 24% in Sinsemilla (the buds taken from unpollinated female plants). Hashish made from the resin of female plant flowers can have a THC. content as high as 28%.