How cannabis and humans evolved together

Published on March 30, 2020 · Last updated July 28, 2020
hand touching craft cannabis plant in farm field
(Jesse Milns/Leafly)

For humans, like most species, surviving life on Earth isn’t exactly easy. But thankfully we’re not in it alone.

Cannabis is part of humankind's 'evolutionary garden,' plants that aid us on our evolutionary path.

For tens of thousands of years, Homo sapiens has been developing mutually beneficial relationships with other species, from dogs and cats to bacteria and breadfruit. These interactions have allowed our different life forms to evolve and flourish together. These relationships are examples of mutualistic coevolution, which happens when multiple species beneficially affect each other’s progress over time.

They’re also a key part of what Dr. Sunil K. Aggarwal calls humankind’s “evolutionary garden.” Aggarwal is a physician, medical geographer, and co-founder of the Advanced Integrative Medical Science (AIMS) Institute in Seattle. In 2013, he published one of the foundational articles on the subject, “‘Tis in our nature: taking the human-cannabis relationship seriously in health science and public policy,” in the medical journal Frontiers in Psychiatry

Useful things to cultivate

The garden he describes is a collection of plants, fungi, and animal secretions that people have cultivated since prehistory, and carried around the world, because of their usefulness for human health and survival, whether as food, medicine, clothing, or other vital supplies.

Most are still embraced today, from honey and grains to caffeine and aspirin. In the past century, however, some cultures have decided it’s a good idea to cordon off certain areas of that garden, despite a long evolutionary history—and current scientific data—suggesting otherwise.

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These blacklisted species include plants and fungi that humans have carefully administered for millennia to treat some of our worst sicknesses and pain, of both body and mind: distilled opium plants for physical agony, for example, or psilocybin tea for processing some of life’s most difficult moments.

Many are powerful, and can even be dangerous (in classic or modern forms) without supervision and guidance. Some have multiple uses, but never caught on in certain cultures.

According to Aggarwal, however, and to a growing number of experts on history and biology, one forbidden species stands out as our biggest loss, and for likely being the single most useful plant that humans have ever gotten to know—and which may even have helped us become “more human.”

That plant, of course, is cannabis.

Earliest cannabis contact

Current research indicates that humans have been cultivating cannabis for tens of thousands of years, but aspects of our biology suggest that the relationship reaches back much further.

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As a medical geographer, Aggarwal has studied the path of numerous natural medicines in different cultures and around the globe, based on anthropological and archaeological evidence.

In response to its harsh Himalayan environs, the plant produced terpenes and cannabinoid chemicals, which the human body is especially suited to process.

Cannabis is one of the oldest medicines on record, he says. It’s been evolving across the planet for tens of millions of years, stemming from its sturdy ancestors in Central Asia. In fact, early cannabis seems to trace back to when the world’s tallest mountain range, the Himalayas, were forming.

“Sixty million years ago, those mountains were formed by the Indian subcontinent hitting the Asian plate,” Aggarwal explained in a phone interview. “All life there had to adapt or die.”

“It created a unique opportunity for this ancestral plant, which appeared 40 to 50 million years ago, to become very active in production,” he said. “There was less oxygen, and increased UV radiation, so the plant had to develop quite a bit of hardiness.”

Cannabis: a hardy survivor

In the millions of years since, cannabis has shown a remarkable ability to survive in a wide variety of climates, from scrub-like Cannabis ruderalis to bush-like Cannabis indica and tall-growing Cannabis sativa and their hybrids, which produce most of our cannabis flower and low-THC hemp today.

Cannabis also appears to have been chemically compatible with the brains of animals, including humans, for much of that time.

In response to its new, harsher environs near the Himalayas, Aggarwal said, the plant seemingly began to produce a wide range of terpenes and cannabinoid chemicals, which the human body—with its balance-keeping endocannabinoid system, which relies on cannabinoid neuroreceptors throughout the body, and can be found in all vertebrate species—is especially suited to process.

Some cannabinoid makers are better than others

The endocannabinoid system is key to our overall health and wellness because it has a crucial role in homeostasis, the regulation of our major biological functions. Our bodies are constantly working to maintain a narrow operative balance, and cannabinoid compounds can trigger the endocannabinoid system to regain this important equilibrium throughout the body as needed.

“The endocannabinoid system has a very important role in protecting the brain from injury, and promoting feelings of relaxation.”

Despite their name, cannabinoid chemicals aren’t unique to cannabis. Chemicals that stimulate the endocannabinoid system can be found in many other plants, like echinacea, turmeric, and kava, to name a few, and may even have structural similarities to the compound type CBG, from which all phytocannabinoid compounds are derived (i.e. the ones that aren’t formed inside an animal’s body, including CBD, THCA, CBC, and many more).

But cannabis “robustly produces tons of them,” Aggarwal said. As a result, “people living near the Tibetan Plateau domesticated the plant early on and found a great number of uses. That includes the neurological side, which is very interesting, as well as good old nutrition, and fibers for cordage.”

“It affects our neurological circuits and has a very important role in protecting the brain from injury, and promoting feelings of relaxation,” Aggarwal added. “Physical and psychological trauma can disturb the brain, and sub-optimize it. The endocannabinoid system, and phytocannabinoids if need be, can set the brain on the path toward regeneration.”

CB1 and CB2 receptors evolved early

In short, Aggarwal said, “this cannabis ancestor happened to make these compounds that bind to receptors in the human system which tap into an even older evolutionarily evolved biological system, which goes back 600 million years: a magnitude older in terms of stages of the formation of life.”

Specifically, those receptor types—known as CB1 and CB2 today—trace back to “when multicellular organisms were becoming multicellular and were trying to figure out how to send communication and modulate action.”

“In biogenetic mapping, when you look at different species and map how old they are, you find cannabinoid receptors going back, and through today. In Homo sapiens, it’s a really integrated system for cell communication.”

Uniquely useful, but not unique

On the cellular level, cannabinoids are also particularly useful for their anti-inflammatory and antioxidant properties, throughout the body as well as the brain. These aspects help the body to maintain optimal performance across its systems from the intercellular level on up, like other natural supplements that ease the way for the body to do its job.

“In terms of their antioxidant properties and neuroprotective properties, cannabinoids are certainly not the only game in town,” Aggarwal said. “But they’re pretty high up there.”

How cannabis went global

Aside from archaeological and biological evidence, humankind’s relationship with cannabis has been documented for thousands of years in printed language, and in oral histories that reach back even further.

As Aggarwal wrote in 2013, “Cannabis’s very name belies its longstanding relationship with humanity, as it was pragmatically given the species name ‘Sativa’ in 1542 by German physician-botanist Leonhart Fuchs, meaning ‘cultivated’ or ‘useful’ in Latin.”

Researcher Rob Clarke, who’s written or co-authored numerous texts on cannabis’ history and biology, told Leafly that, simply put, cannabis seems to be one of the most useful plant that humans have ever come across. “Plenty of plants are used for one purpose, and I can name a number of plants that are used for two purposes,” he said. “But I can’t think of another one that’s used for three.”

For example, “Palms provide us with food, and with fibers for clothing or shelter; bamboo is the same,” he said. Other members of the garden provide us with “both food and drugs,” such as numerous fruits, roots, and grains that people have long eaten but also fermented into alcohol, like cannabis’ evolutionary cousin hops.

But cannabis has all three, Clarke said: “Food, fiber, and drugs.” Meaning that, from just one kind of crop, humans can get an important source of protein, fiber for building and crafting, and medical or cultural tools for our minds and bodies.

On a biological level, stimulating the endocannabinoid system is one part of our bodies’ toolkit for social navigation and balance. Experimental studies have shown that when you boost the body’s endocannabinoid system, people feel the emotional impacts of rejection less, Aggarwal said.

Both species coping with stress

Martin Lee, co-founder and director of Project CBD and the author of several books on cannabis, explained in an interview with Leafly that plants, like humans, have ways of dealing with stressors, and expressing that stress physically. “Cannabis plants do it through chemical signals, odors, things like that,” said Lee. “Plants under stress—if they’re being eaten by insects or whatever—have evolved to communicate with their environment to deal with those stressors.”

“They might have a smell that attracts a predator of the thing attacking the plant, or that will keep potential predators away. And it so happens that these same smells, the same molecules that [cannabis] uses to deal with stress, are very helpful to the human brain in dealing with stress.”

Following the path of empire

In fact, this part of the human-cannabis relationship may explain a lot about the plant’s history and status in the US, and in other Euro-colonized zones around the world, according to Aggarwal and his peers.

By the early 1600s, the British empire and others in Europe were all on board for hemp as a valuable industrial commodity. In the ensuing centuries, they and their colonies would increasingly embrace cannabis medicine, too (leading to Eli Lilly’s early 20th-century cannabis tonics, for example, and the U.S. government’s late 20th-century patents on cannabis as an anti-oxidant and neuroprotectant—but hang onto that thought for now).

During the same timeframe, the European slave trade was booming, with hemp among the top crops that millions of trafficked and enslaved people of African, Central and South American, and North American Indigenous origin were being forced to grow. In the 1600s, Aggarwal said, cannabis as a cultural and spiritual drug probably first appeared in what is now the Americas among these enslaved populations.

By the 1920s, the socially and emotionally helpful plant had been included in any number of reputable Western pharmacopeia, and was arriving state-side in refrigerated barges—hence the name “reefer,” Aggarwal said, becoming an integral part of the fabric of the US jazz scene. By that time, however, most US states and municipalities had also chosen to outlaw the plant despite its medical history here. In 1930, the US deemed the plant federally illegal.

In decades since, however, it’s continued to offer social relief to many of our country’s most oppressed and weighed-upon populations, Aggarwal said. Other researchers have said it also provided some of our most exploited groups with a budding source of financial independence, which may tie directly to today’s underground market.

Key to evolution of critical thinking?

It even seems possible that cannabis particularly helped kickstart our evolution toward being the big-brained, culture-prone critical thinkers we are today. This could have occurred for practical, nutritional, or psychoactive reasons, or (like the plant itself) as a mixture.

In terms of humans’ neurological development and nutrition, Lee explained, “Agriculture is really a turning point as the beginning of hoarding and carbohydrate farming, which was different from earlier diets.” He continued, “It’s possible that cannabis is the first agricultural plant, and it’s certainly one of the very, very early ones. And cannabis is unique because it’s so versatile.”

Today, Lee noted, humans are finding all kinds of new ways to use it (whether in food, medicine, industrial or artisanal fabrics, hempcrete, fuel, or many other forms), as well as better ways to appreciate its psychoactive effects. But as obvious as its usefulness in human lives and history may be, there’s one thing we may never know about cannabis: how the first humans got high.

“We can only speculate how people first discovered cannabis’ psychoactive aspects,” Lee reflected. “It’s hard to imagine it would have come through eating it but, for various reasons, you can imagine they inhaled smoke accidentally.“

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Janet Burns
Janet Burns
Janet Burns is a freelance writer based in Brooklyn who finds drugs, tech, labor, and culture extremely interesting, among other things. She also hosts the cannabis news and conversation podcast The Toke.
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