Fungi have flourished on Earth for quite a while, possibly more than 2 billion years. They've evolved some impressive tricks during that time, including many that are either fascinating or frightening to humans — and sometimes a bit of both.

Some ancient fungi grew nearly 30 feet tall before trees existed, for example, and today a 400-acre fungus in Oregon may be the largest organism on the planet. Certain fungi can glow in the dark, and a few turn insects into zombies. Some species are lethal to humans, while others provide us with valuable superfoods.

And then there are magic mushrooms, also known as "shrooms." These fungi are famed for their psychedelic effects on people who ingest them, an ancient practice dating back to prehistoric "mushroom cults" and shamans who may have inspired Santa Claus. Yet even after centuries of experience, we are only now demystifying many of the magical — and medicinal — powers these mushrooms possess.

This article is not meant to advocate casual use of magic mushrooms, which are potentially dangerous and widely illegal. Even when they provide the health benefits described below, they're typically used in a controlled clinical setting, often with counseling or other guidance from medical professionals. That said, however, they are also natural wonders of our planet that we would be foolish to ignore.

So, for a closer look at these mystical members of Mother Nature's medicine cabinet, here are a few interesting facts you may not know about magic mushrooms:

There are 2 basic types, but about 200 different species.

Psilocybe cubensis magic mushrooms Psilocybe cubensis, aka 'gold top,' is a widely cultivated species of psilocybin mushroom. (Photo: gsplanet/Shutterstock)

Psychedelic fungi fall into two general categories, each characterized by a distinct mix of mind-altering ingredients that make their mushrooms "magic."

The largest, most common group produces hallucinogens called psilocybin and psilocin, and features more than 180 species from every continent except Antarctica. These diverse fungi hail from roughly a dozen genera, but are often lumped together as "psilocybin mushrooms." Most belong to the genus Psilocybe, including well-known species like P. cubensis ("gold top") and P. semilanceata ("liberty cap").

Psilocybin fungi might be so diverse, according to a study in Evolution Letters, because they didn't inherit the genes behind psilocybin from a common ancestor, but just passed them directly between distant species in a phenomenon called "horizontal gene transfer." Psilocybin could have originally evolved as a defense mechanism, the study's authors suggest, deterring fungi-eating pests by "altering the insects' 'mind.'"

The other group is smaller, but has a rich history of religious use. It consists of one iconic species — Amanita muscaria ("fly agaric") — plus a few less famous relatives like A. pantherina ("panther cap"). Instead of psilocybin or psilocin, its main hallucinogens are chemicals known as muscimol and ibotenic acid.

Amanita muscaria, or fly agaric mushroom An Amanita muscaria mushroom grows in a forest near Rieder, Germany. (Photo: Karl-Josef Hildenbrand/AFP/Getty Images)

These "muscimol mushrooms" are related to some notoriously toxic fungi, namely Amanita phalloides ("death cap") and A. ocreata ("destroying angel"). They're generally less poisonous than those killer cousins, but given the high stakes of a mushroom mix-up, non-experts are advised to steer clear of Amanita altogether.

"This is serious stuff, folks," warns food writer and forager Hank Shaw. "Mistake this mushroom for another amanita and you can die." (For more about fungus-foraging safety, check out this intro to mushroom identification by MNN's Tom Oder.)

Magic mushrooms may have given us Santa Claus.

Amanita muscaria mushroom Christmas ornament Amanita muscaria mushrooms may have inspired several aspects of the Santa story. (Photo: borsmenta/Shutterstock)

The story of Santa Claus is pretty odd when you think about it, from magic elves and flying reindeer to Santa's chimney use and his iconic red-and-white suit. According to one theory, many of these quirks come from muscimol mushrooms — or, more specifically, from Siberian shamans who distributed them centuries ago.

A. muscaria has long been valued in Siberia, where human consumption dates back to at least the 1600s. While some of that was likely recreational, Siberian shamans ingested the fungi "to commune with the spirit world," as anthropologist John Rush told LiveScience. The shamans also gave out shrooms as gifts in late December, he noted, often entering homes via the roof due to deep snow.

Santa Claus collecting mushrooms Santa's distinctive style has drawn comparisons to 17th-century Siberian shamans. (Illustration: Yumiyumi/Shutterstock)

"[T]hese practicing shamans or priests connected to the older traditions would collect Amanita muscaria, dry them and then give them as gifts on the winter solstice," Rush explained. "Because snow is usually blocking doors, there was an opening in the roof through which people entered and exited, thus the chimney story."

Those shamans also had a tradition of dressing up like A. muscaria, Rush added, wearing red suits with white spots. Their vision quests could be shared with spirit animals like reindeer, LiveScience points out, which live in Siberia and are known to eat hallucinogenic fungi. And there are other links, too, like Santa's Arctic home or his placement of gifts under trees (akin to how A. muscaria grows at the base of pines). Yet the Santa story is a blend of many influences over centuries, and mushrooms are only a speculative — albeit intriguing — source of Santa's magic.

Humans and magic mushrooms go back millennia.

Maya mushroom stones of Guatemala Examples of Maya 'mushroom stone' statues from Guatemala. (Photo: NIDA [public domain]/Wikimedia Commons)

No one knows exactly when humanity discovered magic mushrooms, but there is evidence to suggest they were used in religious rituals thousands of years ago. Psilocybin mushrooms were important to some Mesoamerican cultures at the time of Spanish conquest, for example, a tradition that was likely already ancient by then.

"[A] genuine mushroom cult in Mesoamerican cultures seems to have existed," biologist Harri Nyberg wrote in a 1992 study, "and its beginnings can be traced to remote antiquity." This is partly due to artwork like the "remarkable 'mushroom stones' of the ancient Mayas and mural frescoes found in central Mexico," Nyberg noted, some of which date back more than 2,000 years. The hallucinogenic fungus Psilocybe mexicana, which is native to Central America, was previously known by the Aztec word teonanacatl — often translated as "divine mushroom."

Psilocybe mexicana mushroom Psilocybe mexicana is one of more than 180 species of psilocybin fungus. (Photo: Alan Rockefeller [CC BY-SA 3.0]/Wikimedia Commons)

In the Sahara desert, rock art from 7,000 to 9,000 years ago may feature even earlier portrayals of psychedelic fungi. The scenes include human dancers holding mushroom-like objects, in some cases with two parallel lines connecting the objects to the dancers' heads. This is not definitive evidence, but some researchers see it as the earliest hints of people using mind-altering mushrooms.

There's also a fringe theory, the "stoned ape hypothesis," that suggests magic mushrooms sparked the boom in brain size and culture of early humans. Many experts dismiss this idea as simplistic and speculative, noting its lack of evidence for tracing human consciousness so neatly back to a single catalyst. Yet the idea has also drawn more interest lately, and even some of its doubters see value in the way it highlighted psilocybin's ability to alter consciousness and the brain itself.

Psilocybin seems to briefly reorganize the brain.

psilocybin molecule illustration A model of the psilocybin molecule, which is made by nearly 200 species of fungi. (Illustration: Wikimedia Commons)

Psilocybin binds to a receptor in the brain for serotonin, and that's thought to cause many of its sensory distortions. Yet along with hallucinations and mood changes, people who take psilocybin often describe an abstract, dreamlike sense of "expanded consciousness." And in recent years, technology like functional magnetic resonance imaging (fMRI) has shed light on what this looks like inside the brain.

In a 2014 study, for example, researchers scanned the brains of 15 volunteers after giving them psilocybin. Activity spiked in the brain network linked to emotional thinking, with simultaneous activity in different areas like the hippocampus and anterior cingulate cortex. (This pattern resembles fMRI scans of people who are dreaming, the researchers noted.) At the same time, activity became less organized in the brain network linked with high-level thinking and the sense of self.

Another fMRI study found a "dramatic change" in brain organization, linking psilocybin with a temporary flurry of neural connections that don't normally exist. "We find that the psychedelic state is associated with a less constrained and more intercommunicative mode of brain function," the authors wrote, "which is consistent with descriptions of the nature of consciousness in the psychedelic state."

Additionally, a team of researchers from the University of South Florida discovered that psilocybin can also bind itself to receptors that stimulate healing. Therefore, it's believed that psilocybin repairs and grows brain cells, which could prove beneficial to those who suffer from depression or other mental health concerns.

Psilocybin may cause lasting personality change.

open window and mountains Openness is a personality trait that has been linked to creativity and divergent thinking. (Photo: Andy Arthur/Flickr)

While brain activity generally returns to normal after psilocybin wears off, the chemical has been shown to have longer-term effects, too. In a 2011 study, researchers measured its effect on five domains of personality — neuroticism, extroversion, openness, agreeableness and conscientiousness — and found "significant increases in Openness following a high-dose psilocybin session."

Openness is a psychological term for someone's attitude toward new experiences, and is associated with traits like imagination, creativity and aesthetic appreciation. Not only did openness generally rise during a psilocybin session, but in nearly 60 percent of study participants, it "remained significantly higher than baseline more than 1 year after the session," the researchers wrote.

That was surprising, they added, since personality doesn't usually change much after the age of 30, especially not like this. "Normally, if anything, openness tends to decrease as people get older," the lead author of the study said in a statement.

The volunteers were all deemed psychologically healthy before the experiments began, the researchers pointed out, and their psilocybin sessions were closely monitored. Some of the participants did report strong fear or anxiety during the sessions, and while that reaction was temporary, Griffiths said it demonstrates the potential risks of trying hallucinogens without expert supervision.

Psilocybin can temporarily 'dissolve' your ego.

silhouette in front of night sky Psychedelics like psilocybin can spur a temporary loss of subjective self-identity. (Photo: Christian Reimer/Flickr)

Some people report losing their sense of self while on magic mushrooms. This "dissolving" of the ego is typically short-lived, but may be related to some longer-lasting effects of psychedelics, like the openness mentioned above. And according to a 2017 study, temporary ego loss could be beneficial in the right context.

"This 'ego dissolution' results in a moment of expanded awareness, a feeling in which the mind is put more directly and intensely in touch with the world," says co-author Philip Gerrans, a philosophy professor at the University of Adelaide, in a statement. "Through this experience it may be possible to re-engineer the mechanisms of self, which in turn could change people's outlook or worldview. The profound sense of connection produced by this experience has the potential to be beneficial for people suffering from anxiety, depression and some forms of addiction."

As co-author Chris Letheby adds, psychedelics offer a wide perspective that can endure even after the drugs wear off. "People who go through psychedelic experiences no longer take it for granted that the way they've been viewing things is the only way," he explains. "Psychedelics can assist in enlightening people about the processes behind their subjectivity. Ego dissolution offers vivid experiential proof not only that can things be different, but that there is an opportunity to seek change."

Even consuming "microdoses" of magic mushrooms can spark a person's creativity, according to an October 2018 study from Leiden University in the Netherlands. Researchers discovered that participants who ate tiny doses contrived more ideas on how to solve a task and "were more fluent, flexible and original in the possibilities they came up with." The study also notes that the participants' intelligence scores and general analytical abilities didn't change, suggesting that micro-dosing is more beneficial for someone's creative thinking.

Magic mushrooms can improve mental health.

YouTube screen shot of psilocybin therapy session A psilocybin therapy session at Johns Hopkins University. (Photo: Psychoactive Substances Research Collection/YouTube)

Although magic mushrooms are widely outlawed as dangerous drugs with no medical value, a growing body of research casts them in a much less nefarious light. Psychedelics have "negligible habit-forming potential," as neuroscientist Nick Jikomes wrote for a Harvard science blog in 2015, and they've even been shown to help treat addiction to habit-forming drugs like cocaine and nicotine.

Magic mushrooms are also increasingly seen as a potential psychiatric wonder drug. Research has shown promising effects on depression, for example, such as a 2017 study that found psilocybin "may effectively reset the activity of key brain circuits known to play a role in depression." The compound seems to boost emotional responsiveness in the brain, another recent study found, suggesting it could relieve depression without the "emotional blunting" often associated with traditional antidepressants known as selective serotonin reuptake inhibitors (SSRIs).

Psilocybin has brought transformative relief from anxiety, too, including in people diagnosed with life-threatening cancer. In one 2016 study, researchers found that moderate doses of psilocybin — combined with psychotherapy — helped cancer patients overcome anxiety and depression related to their diagnosis, leading to a long-term rise in quality of life and optimism. Six months after a single dose (which only lasted four to six hours), about 80 percent of participants still showed significantly reduced anxiety and depression, and 83 percent still reported higher life satisfaction. Two-thirds even described their psilocybin session as one of the top five most meaningful experiences in their lives.

Psilocybe pelliculosa magic mushrooms Psilocybe pelliculosa mushrooms grow in a Pacific Northwest forest. (Photo: JimmyTheWorm/Wikimedia Commons)

Results like these point to the need for more research on psilocybin, a field that has long been limited by legal restrictions. But it's also worth repeating a key caveat about psychedelic therapy: The participants in these studies are carefully dosed and monitored by experts, and their sessions are often complemented by counseling to help them process the experience. Psychedelics can be scary at times, especially if you aren't familiar with their effects, which can vary widely based on factors like mood, temperament, psychological condition and setting. Guidance could be even more important for people already struggling with a chronic mental health issue.

We still have a lot to learn about how magic mushrooms affect the human brain. But thanks to thousands of years of experience — and a surge of modern research — we've at least learned enough to know it's probably worth learning more.

Editor's note: This article has been updated since it was first published in December 2017.


7 mind-bending facts about magic mushrooms
From ancient shamans to scientists studying mental health, humans have a long fascination with 'magic' fungi.