One objection sometimes raised against the search for extraterrestrial life is that our planet is rich with bizarre life forms that we still poorly understand. As a biologist, you are usually so close to the subject that you sometimes forget just how otherwordly our home planet can be. With his beautifully written book Entangled Life, biologist Merlin Sheldrake shook me out of that daze by offering a truly mind-opening book on fungi. Excitingly, he does so without floating off into speculative or esoteric territory.
Entangled Life: How Fungi Make Our Worlds, Change Our Minds and Shape Our Futures, written by Merlin Sheldrake, published in Europe by The Bodley Head (a Vintage imprint) in September 2020 (hardback, 352 pages)
Say “fungus” and most people will think of mushrooms. However, they are only the above-ground fruiting bodies that serve to disperse fungal spores. Most of what a fungus does happens underground. Here, they form mycelium: networks of fine, tubular cells called hyphae. Leave it to Sheldrake to dissolve boundaries and make you rethink everything you thought you knew about living organisms. Mycelium is “better not thought of as a thing, but as a process—an exploratory, irregular tendency” (p. 7), as “a body without a body plan” (p. 55), writes Sheldrake. Mycelial fungi are maze dwellers, probing the underground world in search of resources. Hyphae can branch and fuse, exploring in all directions simultaneously. These amorphous, shape-shifting entities have no fixed shape. Like water, “mycelium decants itself into its surroundings” (p. 58).
And while there is no “brain”, no centre of control, mycelium somehow communicates information through its network. When it finds something to digest, hyphae leading there grow more numerous, while those leading nowhere are pruned. Mycelium communicates this information across its network with surprising rapidity, though how is still open for debate. Pressure changes as in a hydraulic network? Volatile chemicals? A likely candidate that Sheldrake highlights are electrical impulses.
“Mycelial fungi are maze dwellers […] these amorphous, shape-shifting entities have no fixed shape. Like water, “mycelium decants itself into its surroundings“.”
Really questioning the concept of identity are lichens, the symbiotic partnership between a fungus and an alga. Taxonomists have long struggled to make sense of this inter-kingdom collaboration where an organism is made up of two separate lineages. Lynn Margulis turned to them to support her idea of endosymbiosis. But look harder and things become weirder. Recent discoveries show that lichen groups consist of stable partnerships involving a third or even fourth fungal partner. And their identities differ between different lichen groups. It seems that a broad range of different fungal and algal players can come together to form lichens, making them “dynamic systems, rather than a catalogue of interacting components“. One scientist quoted here points out how this leads to the absurdity of “an entire discipline that can’t define what it is that they study” (p. 101).
Fungi shape both the deep past and the present. They played an important role in plant evolution, providing root systems for algae conquering the land 50 million years before plants evolved roots. Today, over 90% of plants still depend on these so-called mycorrhizal fungi. Fungi also have many practical applications, from yeasts providing us bread and beer to mycoremediation (cleaning up waste with fungi) and new building materials. Sheldrake pays particular attention to the efforts of mycological maverick Paul Stamets to save the world one mushroom at a time, and the loose collective of DIY-mycologists that has sprung up around Peter McCoy’s organisation Radical Mycology.
“lichens [are a] symbiotic partnership between a fungus and an alga […] but look harder and things become weirder.”
I admit that I was initially worried that this book might veer into very speculative and spiritual territory. One of my concerns was the question “like father, like son”? After all, Merlin’s father Rupert Sheldrake is both a biologist and parapsychologist who formulated the concept of morphic resonance*—an idea that lacks both empirical support and widespread acceptance. Add to this the topic of psychedelic mushrooms and you have the ingredients for a potent new age brew. Instead, there are two chapters in particular where Sheldrake Jr. shows how to open minds without stepping off the edge of reason.
First, when discussing psychedelic mushrooms and his own experiences taking LSD in the setting of a clinical drug testing unit, he draws parallels to Ophiocordyceps fungi, popularly known as zombie fungi, that take control of insect minds. Though he acknowledges that the powerful and transformative hallucinations induced by psilocybin-containing mushrooms can literally, as Michael Pollan put it, change your mind, he does not confuse them with reality. Rather, they confirm the idea that “our subjective worlds are underpinned by the chemical activity of our brain” (p. 121).
“[Sheldrake] is surprisingly critical of the relatively novel idea of the “Wood Wide Web” […] [pointing] out how plant-centric this metaphor is […]”
Second, he is surprisingly critical of the relatively novel idea of the “Wood Wide Web“. This is the finding that mycorrhizal fungi connect different plants, even different plant species, with each other via their mycelial networks. The popular press has run with the idea of trees talking to each other, helped along by the success of books such as Wohlleben’s The Hidden Life of Trees, but Sheldrake takes a far more balanced and sobering view, shying away from sweeping extrapolations. First, he points out how plant-centric this metaphor is and considers the fungal point of view. Second, mycorrhizal networks are not all about “sharing and caring”, their behaviour is far more ambiguous than that. Our metaphors are fraught, argues Sheldrake, before asking: “Are we able to stand back, look at the system, and let the polyphonic swarms of plants and fungi and bacteria […] be themselves, and quite unlike anything else?” (p. 193)
Not only is the science fascinating and Sheldrake’s ideas and musings perspective-shifting, he is also a first-class wordsmith who has crafted a beautiful book with Entangled Life. When diving into the pungent underground world of truffle hunting, he writes: “truffles provide a depiction of animal tastes—an evolutionary portrait-in-scent of animal fascination” (p. 28). On the question of how mycelium should distribute itself when growing: “How do fungi juggle this kind of trade-off while exploring a crowded rot-scape in search of food?” (p. 54). Extensive footnotes, sometimes running half a page, add much interesting detail, while tasteful drawings made with ink from shaggy ink cap mushrooms give the book a certain cachet. As also evidenced by below teaser trailer, Sheldrake is an able promotor of his own book, really making you want to read it.
In comparison, other popular books on fungi feel like taking a look in from the outside. Somehow, Sheldrake has the uncanny ability to speak as if directly relaying messages from the mycelium. Entangled Life is a gem of a book that mixes scientific astuteness with remarkably entrancing writing.
* a sort of collective memory in nature that would allow for telepathy-type interconnections between organisms
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
Other recommended books mentioned in this review:
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“The Drunken Monkey: Why We Drink and Abuse Alcohol“, written by Robert Dudley, published by University of California Press in April 2014 (hardback, 162 pages)
Dudley’s drunken monkey hypothesis revolves around the symbiotic relationship between flowering plants and their animal seed dispersers. One strategy plants employ to ensure their seeds colonise new areas, away from their parent, is to wrap them in a sweet, fleshy shell: fruit. Animals eat these, the seeds pass through their digestive tract and come out the other end in (hopefully) a different place.
As we all know, sweet fruit tastes the best, and plants use sugar to tempt animals into eating their fruit. But we’re not the only ones who love sugar. I have touched on part of this story in my review of The Rise of Yeast: How the Sugar Fungus Shaped Civilisation, as this fungus also feeds on sugar and in the process produces alcohol, likely as a strategy to kill bacterial competitors). Alcohol, specifically ethanol, is a volatile compound that can be smelled at a distance and can act as another cue to detect ripe fruit. (How do you think those fruit flies always find your bowl of overripe bananas?)
So, Dudley says, our primate ancestors, through the consumption of ripe fruit, had a fairly constant, low-level exposure to alcohol, though the many anecdotal reports of drunken animals are often exaggerated. The maximum theoretical alcohol production, before the substance starts inhibiting yeast’s biochemistry, is below 15%. It took the invention of distillation to produce harder liquor.
And this is the crux of the argument: what used to serve us in our evolutionary past no longer does so in our modern, urban environment. This is the tenet behind the discipline of evolutionary medicine, which seeks to explain human health problems by looking at our evolutionary past. As also popularised in books such as Mismatch: The Lifestyle Diseases Timebomb and Mismatch: How Our Stone Age Brain Deceives Us Every Day And What We Can Do About It, the argument goes that our bodies and minds have not yet had the time to adapt. We crave sugar, salt, and fat, but this instinct backfires in a world where these substances are cheap, easy to obtain, and overabundant. The resulting epidemic of obesity and diabetes is another prominent consequence (see e.g. The Hungry Brain: Outsmarting the Instincts That Make Us Overeat).
“We crave sugar, salt, and fat, but this instinct backfires in a world where these substances are cheap, easy to obtain, and overabundant.”
It’s a neat idea, but is it true? Encouragingly, Dudley is not shy about the gaps in our knowledge and I found The Drunken Monkey to be very level-headed in that regard. There is a dearth of field data on alcohol levels in ripening tropical fruit and in wild animals after eating fruit. Similarly, how important the odour of alcohol is in attracting wild animals in comparison with fruit colour, and how well both function in the complex three-dimensional environments of tropical forest canopies has never been studied in the wild. Many entertaining though challenging field experiments await those brave enough to tackle these questions.
Furthermore, what we do know is quite limited and perhaps not all that relevant. Experiments with fruit flies have provided evidence for a health benefit of systemic, low-level exposure to alcohol. Similarly, epidemiological studies suggest the same might be true for humans, but direct experimental data in vertebrates is lacking. What little data has been obtained in laboratory settings involves animals drinking alcoholic liquids directly, which does not capture the natural context of eating fermented food.
Similarly, Dudley is critical of our clinical diagnosis of alcoholism. It has been notoriously flexible through time, and even today varies by practitioner, cultural group, and country. And importantly, he says, it does not depend on quantitative measures of alcohol intake, but on qualitative measures of impacts of excessive drinking. The search for a genetic explanation of why some people can hold their liquor where others become drunkards is also fraught with difficulty. Twin studies give heritability estimates between 20% to 60%, indicating a large environmental component. Searches for “the” gene for alcoholism (candidate gene approaches) have been replaced by the sobering insight that alcoholism is a complex trait depending on many genes of small effect, requiring so-called genome-wide association studies. (For much more on twin studies, the genetic underpinnings of our behaviour, and complex traits, see my review of Blueprint: How DNA Makes Us Who We Are.)
“[…] these evolutionary mismatch stories assume we haven’t had the time to evolve to better match our new environment. This boils down to the question of how fast evolution happens, which is hotly debated.”
So far, so convincing; Dudley is appropriately cautious. What I am mildly sceptical about with these evolutionary mismatch stories is the assumption that we haven’t had the time to evolve to better match our new environment. As Dudley mentions, findings from both archaeology and the study of fossil teeth suggest intentional fermentation started happening some time between 10,000 to 5,400 BCE (see e.g. Uncorking the Past: The Quest for Wine, Beer, and Other Alcoholic Beverages and Ancient Wine: The Search for the Origins of Viniculture, as well as my reviews of The Tales Teeth Tell: Development, Evolution, Behavior and Evolution’s Bite: A Story of Teeth, Diet, and Human Origins). Is that really not enough time?
This all boils down to the question of how fast evolution happens, which is hotly debated. Traditionally considered a slow process, many argue there are various processes to speed it up, from Stephen Jay Gould’s ideas (see Punctuated Equilibrium), evolution probing multidimensional spaces of possible protein sequences (see Arrival of the Fittest: Solving Evolution’s Greatest Puzzle), the famous domestication experiments with silver foxes (see How to Tame a Fox (and Build a Dog): Visionary Scientists and a Siberian Tale of Jump-Started Evolution, and my review here), or the role of epigenetics (see my review of Extended Heredity: A New Understanding of Inheritance and Evolution). See also my review of Rates of Evolution: A Quantitative Synthesis. Then again, Nathan Lents pointed out, we are a walking comedy of errors: evolution is often limited by the material at hand and the legacy of the past (see my review of Human Errors: A Panorama of Our Glitches, from Pointless Bones to Broken Genes). The problem is that this potentially allows you to invoke slow or fast evolution depending on what your explanation requires, something not addressed here.
That notwithstanding, The Drunken Monkey is a well-paced and level-headed book. It provides all the background you need to understand Dudley’s hypothesis, makes no secret of limitations and gaps in our knowledge, and carefully lays out a research programme. A fine example of striking the right balance between cautious scholarship and imaginative, convincing explanations.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
Other recommended books mentioned in this review:
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