A copy of the book Entangled Life that has been consumed by oyster mushrooms.

Entangled Life by Merlin Sheldrake

I read Merlin Sheldrake’s Entangled Life as a followup to The Hidden Life of Trees. I wanted to get deeper into the fungal side of the forest’s story. However, mycorrhizal relationships are just a small part of what this book explores.

Mycelium preferentially growing in the direction of a block of "bait" wood, even after it has been moved to a new environment.
Mycelial Memory?

For me the wildest parts of this story had to do with the ability of fungi to process information and react appropriately. They appear to be more actively engaged in the world than plants, and in some ways almost resemble animals. This study published in Nature in 2019 found that fungi had a sense of direction and some kind of memory. The researchers put a small block of wood inoculated with a fungus into an environment where it could grow and explore and eventually discover another block of wood. Then they’d remove the original block of wood and put it in a new environment, and they found that the mycelium would continue preferentially growing and exploring in the direction that had led to the “bait” before!

Mycelial Minds

In addition, it’s been shown that information propagates through mycelial networks faster than can be explained by chemical diffusion or the active transport of cellular fluids. It turns out that at least in some cases, the hyphae can transmit waves of changing electrochemical potentials in much the same way that neurons do in animals. So there’s clearly some amount of information processing and sensing of the environment going on, but nobody seems clear on how it works, or how much is happening.

This gets extra weird in the chapter that talks about the ways in which fungi directly interface with brains. Why do some of them make hallucinogens? Apparently psilocybin has evolved independently in several different lineages of fungi. The molecule that LSD is based on is synthesized by the ergot fungus. How does it help a fungus to make a difficult molecule that dissolves the egos of complicated mammals? Why do these compounds affect the brains of such a wide range of animals? Is it really just a coincidental side-effect?

He also gets into the new wave of research into the use of psychedelic drugs to treat addiction, depression, and other mental illnesses. Unlike most drugs, where the effect is pretty much just chemical, and they do their biological work largely regardless of your psychological experience of them, the medicinal utility of psychedelics seems be a function of the experience itself. Given the range of societies that have used psychedelics in analogous ways for thousands of years, this is maybe not so surprising. Still, it’s nice to see western society maybe getting over it’s deranged mid-20th century fears of these drugs.

And then there are the ophiocordyceps fungi that turn ants and other invertebrates into zombies, forcing them to take very specific actions that help spread the spores of the fungi far and wide. Again nobody knows exactly how these fungi work, but apparently they colonize the entire body of their host, with hyphae interwoven through muscle fibers and organs — but curiously, not the brain.

Promiscuous Collaborators

A tree branch almost completely covered with a grey-green lichen, made up of both fungal and algal partners.
A fungus and and alga took a lichen to each other…
CC-BY-2.0 Alex Proimos via Wikimedia

Another running theme in the book is the promiscuity of fungal collaborations. Lichen are hybrid organisms that bring together fungal and photosynthetic partners to make a more robust and adaptable whole. But it’s not a fixed one-to-one relationship. The same partners can work with a variety of different species. And sometimes an “individual” lichen is made up of 3 or 4 or more “separate” organisms! That may reproduce together as a whole, or not, depending on the situation.

Fungi have been working with larger plants for at least as long as there have been plants on land. Almost half a billion years ago, they grew into some of the first towering organisms, called Prototaxites, before any plant had figured out how to stand tall.

As with the lichen, one type of fungus can have relationships with many different species of plants at the same time. Different mycelial networks can share resources with each other. Individual plants can have relationships with several different kinds of fungi — including cheating in some cases! Bright red snowflowers and striped candycanes don’t photosynthesize at all, and instead tap into mycorrhizal networks, apparently only to extract resources without giving anything back.

Fungi engage in arbitrage. They will extract mineral resources like phosphorous from one location, and move it to plants that need it in another. In exchange, they get supplied with sugar, but the exchange rate varies by location depending on how plentiful phosphorous is. The same fungus will “charge” different prices to different plants. They also apparently maintain a genetic library of different kinds of enzymes, for disassembling different materials. In some cases mycelium will encounter a new material, and be unable to take it apart initially, only to suddenly realize a week later that in fact it does have the key, and start noshing down. Bacteria get shuttled around in mycelial networks too, like some kind of micro-subway. Is it done with purpose? Are they another resource to be redistributed? Or are they just along for the ride?

Then there are the termites and leaf cutter ants that have both domesticated (or been domesticated by?) their own independent species of fungus, which they cultivate inside dark chambers underground, feeding them leaves and wood pulp.

Given that some mycelial networks span many acres, and may live almost indefinitely, it’s hard not to wonder what kind of complex resource shuffling and information processing they’re engaged in under our feet. The fungal way of life is as different from ours as it is from plants. While humans have fermented foods for millennia, we haven’t dependent as completely on fungi as we have on our domesticated plants and animals, and so much of what they do takes place out of sight and out of mind, that it seems like they’ve been neglected a bit by science so far. But it sounds like this is changing, and there will be plenty of truly psychedelic findings in the years to come.

What to Read Next?

  • How to Change Your Mind by Michael Pollan, for more on the pharmacological uses of fungi, and the ongoing research renaissance.
  • Finding the Mother Tree by Suzanne Simard, for a deeper investigation of the plant side of mycorrhizal relations, and how the forest works.
  • The Overstory by Richard Powers would be different — a novel about the relationships between people and trees.

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Zane Selvans

A former space explorer, now marooned on a beautiful, dying world.

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