[Editor’s Note: Fascinating article. There are theories about viruses creating mutations by scrambling parts of DNA. Could THC have been created that way?]
Tetrahydrocannabinol (THC) is unique among psychoactive compounds. Thus far in history, only one other natural chemical creates a similarly intoxicating experience — a little-known liverwort from New Zealand. For decades, researchers have speculated that the cannabis plant produces THC to aid in its own survival.
There’s no questioning that this is true. For one, the compound seems to act as a built-in sunscreen, shielding delicate leaves and flowers from harsh UV-B lightwaves. Secondly, the cannabinoid is a potent natural anti-microbial and insect repellent, protecting flowers from pests and infection.
Here’s where things get weird. The cannabis plant may not have developed the ability to produce THC on its own. Instead, recent science suggests that the herb borrowed the DNA from other organisms. Most notably, the cannabis plant took inspiration from ancient gene-scrambling viruses. This biological borrowing, as it turns out, may be the reason why intoxicating cannabis and CBD-rich hemp separated from one another.
The Origins of THC
It turns out, cannabis aficionados all over the globe have an accident to thank for the development of THC.
After completing an exhaustive sequence of the cannabis genome, researchers from the University of Toronto, the University of British Columbia, and the Icahn School of Medicine at Mt Sinai in New York found that the world’s favorite herb inherited its ability to produce the psychoactive after a series of infections millions of years ago.
Viral invasions of the genome are nothing new, most plant species contain millions of garbled fragments of their own DNA mixed with that of viruses. These infectious viral entities are called retrotransposons, and they’re sometimes referred to as “genetic parasites”.
Remnants of these genetic parasites, called retroelements can be passed along from generation to generation — a heritable trait that, at first glance, doesn’t seem to follow the rules of natural selection. Instead of developing the ability to produce THC automatically for its own benefit, the cannabis plant got a little help.
This viral help not only made the plant more appealing to humans later down the line, but it also split the cannabis plant into two generalized chemovars: intoxicating marijuana and fibrous hemp.
Ancient Viruses Cause Split Between Cannabis and Hemp
Prior to infection, there is no indication that the plant could produce either THC or CBD as two unique chemical compounds. Instead, the cannabis plant seems to only have had one enzyme that perhaps made chemicals that were similar in structure to either cannabinoid. After infection, the virus DNA coupled with natural DNA replication split the genetic makings of one enzyme into two, allowing certain plants to produce either THC or CBD.
It is important to quickly point out, however, that it’s technically incorrect to say that these viruses allowed the plant to produce THC. Instead, the viral infection enabled the plant to produce THC-acid. This acid then converts to THC slowly after exposure to heat and the elements. The cannabis plant synthesizes THC-A using an enzyme, which is a special protein that facilitates the chemical reaction that puts THC-acid together.
It’s this enzyme, along with the enzyme that produces CBD-acid, that the ancient viral infection seemed to create. After viruses made themselves at home millions of years ago, it caused the enzymes that make either THC-A or CBD-A to drift apart.
Over time, the research scientists presume, these different plants were selectively bred by humans, who relied on both plant varieties for food, fiber, medicine, and spiritual purposes. An amazing fact, considering that without infection, these revered molecules may have never come into creation.