Review : Entangled Life (part 1)

David Attenborough once said his producers were none too keen when he suggested they make an entire TV series about plants, but even he hasn't tried to do one about fungi. Which is a terrible shame. After reading Merlin Sheldrake's Entangled Life, doing endless superb shows about zoology but not fungi seems a bit like making an otherwise-outstanding world atlas that completely misses the existence of Asia.

I must say I wasn't too impressed with the way the book begins. It spends far too long on introducing truffles by way of truffle-hunting, too caught up in an uninteresting anecdote about the effect of truffles on humans with little about the organism itself (for some reason it's popular among all longform pieces that you have to start off with something completely unrelated to your advertised content). Thankfully, this opening is an anomaly. We're soon deep into the science of fungi, which Sheldrake describes with tremendous enthusiasm (sometimes perhaps a bit excessively so) but also a deft, eloquent blending of gentle rhetoric with hard science. Uncertainties - and there are many - are not hidden from the reader but made part of the fascination. Anecdotes are generally used with some successful subtlety to convey a point without the need for direct exposition.

Overall, it's a marvellous book. Although it does have the occasional dud bit of narrative (usually stories which don't add anything relevant), I have no hesitation in giving this an easy 9/10. It truly is like diving into an entirely alien world, of organisms at once so familiar, so common, and yet so very much stranger than we suspect. Sheldrake does a first-rate job of introducing a topic that deserves much wider attention, blending science, philosophy, and personality into a brilliant combination.

(Incidentally, Merlin Sheldrake is the son of the more notorious Rupert Sheldrake, but do not for one moment let that deter you.)

It's hard to isolate particular topics I found most interesting. Nevertheless, I've narrowed it down to four : two scientific and two philosophical. First, let's see how fungi completely challenge our most basic notions of how life is organised. Then let's choose an ever-popular topic and try and see if there's any evidence they can think. In part two I'll move on to philosophy proper, and take a brief look at how fungi can providence evidence both for materialism and idealism depending on your point of view. Finally I'll circle back to see how they challenge our notions of identity and individuality.

Networked life

There's a rubbish episode of Stargate SG1 featuring some apparently primitive people living in harmony with some weird white blobs. They exist in a symbiotic relationship, with the daft-looking idiots singing to the interconnected plants to make them grow and... make the people... happy, I guess ? I dunno. 

As I say, it was a rubbish episode. Trouble is, the "plant" in question bears more than a passing resemblance to fungus.

First, the scale. In the episode the plants can grow to be a few metres tall, significantly larger than what we usually think of with fungi. But back in the Devonian era, says Sheldrake, a species called Prototaxites did indeed reach such heights as are normally found in Tamriel. But the phrase "the tip of the iceberg" looms forth like the underside of said proverbial iceberg, because these visible structures are probably the least interesting and certainly the smallest part of the fungus as a whole.

In Stargate the plants are connected underground, though to what extent is unclear. In real life, at least one fungus is a contender for the world's largest organism, spread underground across several miles. It doesn't have the giant fruiting bodies (a.k.a. mushrooms, the bits we normally see) as in Stargate, nor does it have the extremely rapid growth rate, but the organism as a whole dwarfs anything seen in fiction.

And that's just one organism. Collectively, the scale of fungi is - and I don't use this expression lightly - truly astronomical :

Globally, the total length of mycorrhizal hyphae in the top ten centimetres of soil is around half the width of our galaxy. However, fungi don't stay still. Mycorrhizal hyphae die back and regrow so rapidly - between ten and sixty times per year - that over a million years their cumulative length would exceed the diameter of the known universe. Given that mycorrhizal fungi have been around for some 500 million years and aren't restricted to the top ten centimetres of soil, these figures are certainly underestimates.

This gargantuan mass affects ecology on a global scale*. While this is not one single entity, each individual fungus forms a highly complex network that requires we un-learn all our ideas about what an organism is and should be.

* For brevity I will omit the impacts of fungi on climate and agriculture, but suffice to say they are profound.

The root-like structures that make up the greater part of a fungus are called hyphae. with the network as a whole the mycelium. The fruiting bodies are tiny in comparison, but are made of the same essential structures (interestingly, no-one understands how hyphae coordinate their growth to form a mushroom). Rather than move around as animals do, the fungal solution of how to reach essential resources is just to grow there. In this regard they're more like plants than animals, but unlike plants, this growth is highly dynamic. The whole network structure can change in a matter of days in response to varying conditions.

The tip of a hyphal structure is the nearest a fungus gets to the classical picture of an individual entity. Here, small "bladders" arrive at the tip from the rest of the network and are rapidly fused, sometimes so rapidly you can watch them grow. The hyphal tips can extend the network linearly, branch into a multitude of additional tips, or they can rejoin and fuse so that the branches create a web. Though they form one distinct, connected item, and don't have unlimited rules for how they grow, there is no central directing command structure at work. This is a life form which is a pure network, like a single individual and a hive all at the same time. Struggling for metaphors, Sheldrake likens this hyphal swarm to a tribal song :

Unlike the harmonies in a barbershop quartet, the voices of the women never weld into a unified front. Nor does any one voice steal the show. There is no front woman, no soloist, no leader... Mycelium is polyphony in bodily form. Although each [hyphal tip] is free to wander, their wanderings can't be seen as separate from the others. There is no main voice. There is no lead tune. There is no central planning. Nonetheless, a form emerges.

This clearly gives the fungus tremendous flexibility. Though I did wonder : why be long ? If you need resources, why not just move to them ? How can some fungi manage just fine being very small indeed while others are enormous ? What is the point of forming such gigantic, intricate, ancient networks when smaller ones, in the same environment, apparently do just as well ?

Nobody knows. Mycology seems to be very much more in its infancy than most contemporary science, and a lot of major questions are for the present simply unanswered. Though one major omission which I presume people do understand is what happens to the parts of the mycelial network that the fungus discards - how exactly is the network reconfigured ? Do parts of it die off or are reabsorbed in some way ?

However, we can say a bit more about what the active network does. Their interactions with other organisms vary from full-on predatory, to parasitical, to truly symbiotic. They entwine themselves around the roots of plants and even extend inside them. For certain they enable the transfer of carbon, phosphorous, and nitrogen in significant quantities, but it also seems that they can transfer DNA, growth hormones, and herbicides for plants wishing to kill invaders growing nearby. 

This "wood wide web" has gained some popularity on the more familiar WWW*. Sheldrake points out that there's (among many others !) a key difference between the two : in the internet, the physical connecting cables are essentially passive data pipelines and nothing more. In the forest, the mycelial network is an organism itself : for all its intimate physical bindings with other organisms, it ultimately has its own needs, its own goals. One almost gets the impression that maybe the fungus is farming the plants, deciding which ones need more resources so the plant can capture more carbon for the fungus, which ones are thriving and don't need assistance...

* Sheldrake mentions the structure of the network as having a similar power-law shape to the internet : a few nodes have many branches, many have much fewer, with no typical number of connections. However, there seems to have been little work done on this (small fungi change rapidly while large ones are exceedingly difficult to map), and it isn't at all clear if and how the structure affects any capacity for cognition.

It's a highly imperfect analogy. But with such a complex network which challenges our whole notions of bodily identity, it could hardly be anything else. Far too much is still unknown.

Do fungi think ?

I've said that fungi have "goals", and I have to wonder to what (if any) extent that it comparable to human intentions. In transferring resources (certainly on scales of hundreds of metres), fungi are clearly causing complex outcomes. They mean we cannot think of plants as individual entities any more, but themselves part of the fungal network. But does the fungus act purely mechanically, utterly driven by stimulus response, or is it possible that it is actually thinking ? Is it making conscious choices ?

This may seem a bizarre idea. But then, the idea of a vast, complex network of a shapeshifting, hive-like organism that connects a multitude of different lifeforms - for fungi may also help plants communicate in producing toxins to fight off insects - is also bizarre. I think it's an idea we have to take seriously, if skeptically.

I've covered the idea of plant consciousness many times already, so at this point a link-summary might be helpful. Skip the next paragraph if you want to stick with fungi.

In this one I consider whether we need senses for consciousness or not, and note the problems with defining memory and the difference between simple stimulus response and deliberate intention (see also this). In this piece I note that plants can change their behaviour in response to changing conditions, arguably displaying a sort of learning, but with important caveats as to the control tests in the experiments. Here I consider whether the forest as a whole, rather than individual trees, might be conscious, noting that because consciousness is not a physical parameter*, it's presumptuous to state that plants simply cannot think. I elaborate somewhat on this here in response to a report by some angry botanists stating that plants simply cannot be conscious because they're not complex enough, but note that some of their objections do seem plausible. That led me to a bit more of an in-depth look at experiments showing that plants can make choices that require knowledge and intention**, although a disappointing follow-up found that the experiment could not be replicated. Finally, I consider a rather extreme view that plants are every bit as conscious as the rest of us here, and on a related note, I say that maybe Google's AI chatbot can maybe said to be sapient (intelligent, problem-solving) but not sentient (having sensory awareness). As to whether having both sapience and sentience together is enough to count as consciousness, I don't know. Possibly.

* A statement hardly without controversy ! More on that in the future.
** The key being that the choice must be indirect. Growing towards water doesn't count as requiring even a modicum of thought. Growing towards a button that releases water might. This would not entail any understanding of how the release mechanism works, but we couldn't ascribe such behaviour to pure sensory-driven "instinct" either.

Perhaps we should start with fungal behaviour, meaning how they respond to changing conditions. Well, for one thing they can hunt. Their prey are tiny nematode worms, for which they employ a variety of weapons : adhesive nets and branches, inflatable snares, toxins, and harpoons. These are active hunters to easily rival the Venus flytrap. And they hunt deliberately. They don't create their weapons until the sense the presence of worms; until then, they make do with other sources of nourishment.

Oddly enough their main means of detecting prey appears to be scent. This isn't what I expected at all : sure, mushrooms and truffles can be aromatic, but how does smell propagate underground ? Well, apparently it does. Some are also highly sensitive to light - and not just light in general, but different wavelengths. One species is highly sensitive to the movement of air, and can also avoid obstacles by means as yet unknown.

And they're versatile. At least one species is capable of predating on worms, decomposing dead matter, parasitically feeding off plant roots, and of blocking other fungi. "How it chooses between its many options", says Sheldrake, "is unknown".

But does it choose, or is this pure - though undeniably complex - stimulus response ?

That is very much harder to answer. They do appear to posses a kind of memory, noting the problems of distinguishing between "inner life" memory and simply being physically altered (like an abacus) that I mentioned with regard to plants. In one experiment, fungi were grown with a dish with a block of wood. Once they made contact, the fungus rearranged itself to concentrate in the direction of the block. Then the mycelium were heavily trimmed and the remaining fungus placed in a new, fresh dish, where the hyphae continued to grow in the direction where the block of wood should have been.

Fungi also fuck. Their "genders" are quite different to ours : any two dissimilar mating types can mate to produce offspring, but the roles of paternal and maternal (donating and receiving genetic material) are interchangeable and not fixed to each mating type. They apparently find each other through smell, and produce spores which can swim. 

And they can solve problems. Slime moulds are justifiably well-known for being able to create complex maps; they can also learn from each other. So they have memory, hunt, seek out partners to mate with, can sense their environment and respond to it in different ways, and can alter their behaviour through learning. They can sense (at the very least) touch, light, and smell. 

Let's be honest, this sounds a lot like most animals. Few sane people would deny that an animal displaying these characteristics had at least a rudimentary consciousness.

There's one more thing that should be mentioned. As well as various nutrients, mycelial networks can also transmit electrical signals :

When the wood came into contact with the mycelium, the firing rate of the impulses doubled. When he removed the block of wood, the firing rate returned to normal. To make sure the fungi weren't responding to the weight of the wooden block, he placed an inedible plastic block of the same size and weight onto the mycelium. The fungus didn't respond.

This particular researcher doesn't think that fungi are literally brains (they are too dissimilar for that) but they might be brain-like : doing the same or similar jobs of memory, learning, decision-making and more but by a different method. 

So, do fungi think ? Do they have inner, mental lives ? Do they experience qualia ? Do they make choices beyond purely mechanistic responses ? Surely, this is at least a possibility we have to consider. True, they have nothing like the centralised system found in most animals : but the octopus outsources much of its decision-making capabilities to its individual arms. Perhaps fungi take this to the extreme. Their brain and body are one and the same, a unified, hive-like network all in a single organism. 

Throughout the book, Sheldrake is careful to note the use of imperfect analogies and the difficulties of metaphors. He's also sympathetic to the view we should take these comparisons literally. When he says fungi communicate, he really means it. And yet :

How best to interpret the behaviour of shared mycorrhizal networks is a sensitive subject. Some researchers are concerned about how wood wide webs are commonly portrayed. 'Just because we found that plants can respond to a neighbour', Johnson told me, 'doesn't mean that there is some altruistic network in operation.' The idea that plants are talking to each other and warning each other of imminent attack is an anthropomorphic delusion. 'It's very attractive to think that way,' he admitted, but it's ultimately 'a load of nonsense'.

Which made me want to grab this Johnson fellow by the shoulders and yell at him, 'Good God man, why ? Why is it nonsense ?'.

To be fair, there does not seem to be a clear example of a fungus or a plant making an indirect choice. Pavlovian responses in plants are controversial but there doesn't seem to be any hint of that in fungi as yet. Then again, given their radically different nature, we would do well to remember that designing such a test is fraught with difficulty, otherwise we arrive at nonsensical results like the mirror test. 

The nearest I could find in Sheldrake (who remains gloriously ambiguous as to what he himself thinks) to the possibility of fungi making decisions comes in the wood wide webs. Fungi, apparently, are an economist's dream : a rational actor. Where phosphorous is scarce, the fungus extracts (or the plant gives*) more carbon in return, and vice-versa. But it will also transport resources across its network efficiently. It will take the phosphorous from places where it's abundant and transport them to plants where it's scarce, so getting greater carbon in return. How the network coordinates this is unknown, but it seems there's more going on than the action of individual hyphal tips. The network as a whole does something.

* A running theme throughout the book is how much language and metaphor matter. We just don't know enough to state things rigorously, but we have to venture some statement or we'll get nowhere.

So can plants and fungi think ? As usual, results are inconclusive. Trees and fungi alike are bigger and live longer than us and have had longer to evolve. They work differently, but they have senses and take action : why should they not have a form of consciousness, of decision-making, albeit one resulting from a different process from our own ? Or, if we are purely mechanistic, deterministic creatures, but clearly conscious, why should fungi not be the same ? In a materialist framework, just because something is a pure, unavoidable stimulus response doesn't mean it isn't also a conscious choice.

Things could be considerably weirder than that. To understand thought, we might have to rethink the very nature of reality. And that altogether stranger yet not less valid perspective is something I'll look at in part two.