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Planta Sapiens

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I enjoyed this book a lot!

The subject had some fascinating insights and I found it made me think back upon some of my own past research on animal cognition and agency in literary studies (Medieval literature). I found the correlations that the authors made between animal and plant cognition fascinating.

The writing style was engaging and the information provided was in-depth, yet still accessible to a general readership.

This is one book that I'll definitely go back to read again -- and that is not something I often say about non-fiction books.

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Plants aren't the passive organisms we tend to think they are. They use chemical signals to communicate. They respond to defend themselves from insects and disease. But could they be sentient? In an entertaining and easy-to-read narrative style, this book reveals fascinating facts about plant biology that may change the way you look at plants forever.

Thanks, NetGalley, for the ARC I received. This is my honest and voluntary review.

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With all of the focus lately on sentient beings, including AI and chatbots, it might not seem so strange to be looking at "The New Science of Plant Intelligence." That is exactly what two academics, Paco Calvo (professor of philosophy of science at the Universidad de Murcia in Spain) and Natalie Lawrence (writer and illustrator with a PhD in the history of science) do in their new book, PLANTA SAPIENS. They begin by urging caution, saying, "whether you are deeply skeptical of the possibility that plants might have intelligence or are an enthusiastic believer in the supernatural wisdom of other lifeforms, we all need to broaden our minds carefully. ... What you read here will be a challenge to anyone's preconceptions." Next, they describe the science in support of plant intelligence; they ask their readers to think deeply about plants, contemplating, for example, whether plant behaviors are merely genetically programmed reactions or actual engagement with their environment. Calvo and Lawrence praise thinking creatively and embracing trial and error – arguing repeatedly for open minds and "a new approach of cross-fertilisation between different specialisms [disciplines]." Although a bit long-winded in places, the authors pose numerous intriguing ideas and conclude by saying that studying plants may help humans "to better comprehend the nature of our own minds." Notes and sources, plus a helpful index, comprise roughly twenty percent of this innovative text. PLANTA SAPIENS received a starred review from Publishers Weekly which described this work as a "mind-blowing debut."

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What an intriguing book! I absolutely loved it. As a gardener, it’s always been obvious to me that plants have feelings. The way that hydrangeas perk up after being watered or the way zinnia leaves fold upward to shield their wound after being cut are obvious signs these species have feelings.

Consciousness, on the other hand, and the ability to think, are totally new, but not too far-fetched, concepts to me. The author explained it best with the comparison of the octopus. Octopuses can move their tentacles separately from each other, and the movement is controlled not by the brain itself but by each individual tentacle. It’s nearly impossible for humans to imagine living this way, and it’s similarly difficult for humans to imagine what it must be like to live as a plant. However, just because we do not interact with our environments in a certain manner doesn’t mean that other species do not.

The author gives some very credible evidence for plant consciousness and also addresses his critics’ viewpoints and their attempts to discredit him. Plants can be put to sleep. Mind BLOWN! If that’s not enough to get you interested in the possibility of plant consciousness, I don’t know what is. In addition to that fact, they also make choices, about which soil to send their roots to, which colored poles to grow up. Their children, or seedlings, also make choices and assumptions based on their parents’ experiences. I’ve heard plants can grow better in reaction to someone talking or singing to them. I’ve always thought that concept was a bit silly, but now it’s not that inconceivable.

The author uses all of this evidence to purport that plants need the same protection and ethical treatment as animals. In this regard, I don’t think he spent enough time explaining why or how. Sure, I think being lazy and not watering your houseplants until they die is unethical, but how would a farmer treat his crops differently when harvesting? Should humans avoid eating plants for the sake of their ability to feel and be harmed? And then what would we eat if not animals either? Or maybe the author is simply trying to make a point that self righteous vegans really have no moral ground to stand on as we are all dominating and harming our food sources regardless of our dietary habits.

The author leans heavily on Darwin’s research and seems to even worship him a bit. Although I don’t agree with all of Darwin’s theories, I appreciate that he made an enormous contribution to science and left behind so much research and knowledge for others to build on. As far as what I do or do not believe though, I think the thing I appreciate most about the author is his questioning of the “traditional scientist” and their inability to question widely-accepted theories or consider other possibilities. We know the Earth is not flat but those who claimed it was round were laughed at and called mad by the majority who believed that widely-accepted theory of that era. Similarly, perhaps scientists will look back on this book 200 years from now on and call the author the father of the study of plant consciousness. It’s so funny that scientists, who should be the most open-minded, unbiased people in the world, will often cling to previous theories hailed as truth by the majority until later being proven wrong by that one “crazy” person who dared to look at it differently and keep searching.

Scientist or not, I think it’s important for everyone to consider all possibilities, and this book is an excellent place to start if you want to challenge your own long-held beliefs.

Thank you, NetGalley and W. W. Norton and Company for the ARC!

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This was an interesting read, though a little more on the soft-science side. I enjoyed reading about the various tests that MINT lab has done in its efforts to prove plant intelligence and sentience and the subsequent challenge to ethics that would result. While it was interesting to see connections to their current studies to some other studies done in the past, I'm not entirely sure I'm convinced of their findings. The authors are leaning into multiple subjects that spur their interest/testing (philosophy, biology, psychology, physiology - to name a few) and such a wide variation of methodologies feels… conflicted. It does spur interesting thoughts however, so A++ for lighting up curiosity. Show me more science, more proof, more studies tested in different labs that support these fascinating leaps and I'd happily read them. As it stands, I like my science with more hard facts, so I was a little disappointed because the book didn’t support my expectations.

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The title of Thomas Nagel’s 1974 paper “What is it like to be a bat?” is often appropriated when a philosopher or scientist wants to muse about the possibility of some creature other than a human being conscious—and self-conscious. Nagel’s point was that consciousness is subjective and unable to be reduced to its physical components, be they a brain or a set of connections in an artificial neural network. Consciousness feels like something. You and I know what it’s like to be us. Probably your dog does too, and also your cat, your goldfish, your parakeet, a tiger stalking its prey in the jungle, a mouse hiding from a prowling cat. There are creatures, however, who are very different from us—bats, in fact, who use echo location rather than sight to navigate, or octopuses whose brains are distributed in their tentacles as well as their heads—and they complicate our usual attempt to understand a member of a species based on an assumption that they think more or less like we do. Even within the animal kingdom, the question arises as to how far down the phylogenetic scale we can go and still impute human-like motives and experiences to creatures such as flatworms, mosquitoes, polyps, bacteria, paramecia, amoeba.

Our tendency to attribute some sort of consciousness to other animals is mostly related to how similar they seem to us. A robot arm doesn’t seem to be aware of itself, but if we construct a human-like robot, an android, with a face and facial expressions and have it carry out human-like actions, it becomes easier to think that it may have an inner experience of being itself. This is why we can identify with Data, the android from Star Trek the Next Generation or Ava in the film Ex Machina. Some scientists and philosophers have not let the lack of similarity to ourselves hinder their exploration of the idea that both intelligence and consciousness exist in living entities far different from ourselves. In his book, The First Minds, psychologist Arthur Reber has suggested that even single cell prokaryotes may be aware of both their surroundings and themselves (2018). Prokaryotes preceded eukaryotes and if sentience were present in prokaryotes, it ought then to be present in both animals and plants, both of which are eukaryotic. In his book, Planta Sapiens, Paco Calvo, professor of the philosophy of science and principal investigator at the Universidad de Murcia’s Minimal Intelligence Lab (MINTLab) in Spain, and science writer, Natalie Lawrence, have taken this suggestion seriously and written a provocative account of why Calvo thinks plants are not only intelligent, but also conscious.

Calvo’s thesis is primarily inductive, in that he examines plant movement in vines and root growth, tropisms, electrical conduction, and “defensive” actions such as the closing of leaves and tries to imagine the cognitive “machinery” required to carry out such “behaviors.” His evidence is impressive and sometimes startling. Plants are known to orient toward the sun (you can see this in your own garden), and some plants, such as sunflowers, will orient toward the sun and follow it as it moves across the sky. At night, they re-orient themselves to anticipate the next day’s rising sun. Dig them up and turn them 180 degrees, and within a few days, they will re-orient their movements to match the path of the sun. By doing so, they maximize both photosynthesis and the likelihood of visitation by pollinating insects. Plants will also alter their growth patterns, in terms of their roots and their stems, trunks or leaves, depending on the plants surrounding them, all to the end of maximizing access to resources such as sunlight and nutrients. They can even affect and be affected by the growing conditions of their neighbors, so that they adopt some of each other’s growing patterns. Their roots can alter their direction of growth by turning horizontal or even upward to avoid a barrier, or to seek moisture.

Plants can learn, as demonstrated by the habituation and discrimination learning of leaf-closing in Mimosa pudica, described by both Calvo and Stefano Mancuso in his book The Revolutionary Genius of Plants (2018), which I recently reviewed (Dorman, 2023). Both Mancuso and Calvo spend a lot of time describing the sensitivity of plants to the same anesthetic chemicals that render animals’ unconscious. Automatic reactions such as leaf-closing in Mimosa pudica or the closing of a Venus Flytrap on an intruding insect are slowed, then stopped, with application of a substance such as chloroform. Not only that, but the electrical impulses that accompany a movement such as the snapping shut of the Flytrap, are muted or absent under anesthesia, similar to interfering with the electrical impulses in an animals’ brains, which are a part of Christof Koch’s indication of consciousness in humans and other animals (Koch, 2015). Not only that, but plants can also respond with chemicals such as dopamine to incidents of damage or destruction, as though they were attempting to relieve pain (which Calvo thinks should lead us to consider the ethical consequences of our actions toward plants).

The above are just a few of the remarkable findings reported by Calvo in his book. Underlying his hypothesis of plant cognition is the idea that, like humans and other animals, plants’ “phytonervous systems” as Calvo provocatively refers to them, contain models of the plant’s expected environment and base the plant’s actions on sampling the environment and adjusting itself to adapt to the actual environment in order to bring the predicted and the actual conditions as close together as possible. Calvo believes that, similar to animals’ nervous systems, the plant phytonervous system is based on electrical signals being passed from one location to another.

Even if there are similarities between the workings of plants’ and animals’ “nervous systems” (the quotation marks are to acknowledge the fact that plants don’t actually have neurons), Calvo is cautious about over-anthropomorphizing “what it is like to be a plant.” Plants are even less like us than either bats or octopuses. We can try to understand what the plant feels like “from the inside,” but it is doubtful that we will be very successful. But is the whole idea that there is something that it is to feel like a plant even warranted? I have to admit that I came away from reading Planta Sapiens impressed, but not convinced. To his credit, Calvo is a philosopher, but he thinks like a scientist. He expresses most of his conclusions tentatively, and labels them as speculations, not facts. Because of this, I don’t reject his conclusions outright, so much as I doubt them, but, in most cases, I allow that they are possibilities.

Plants display what may be termed “intelligent” behavior, but it is not clear that intelligent behavior requires a conscious agent to produce it. Artificial intelligences also produce intelligent behavior, and the author of Planta Sapiens, as well as other authors such as Arthur Reber, reject the idea that AIs are, or probably ever will be, conscious. Calvo makes a distinction between what he calls “adaptive responses” and those that require cognition. Some of those mentioned above, such as orienting toward the sun, are said to require no cognition on the part of the plant. But the distinction between those responses that require cognition and those that don’t is a fuzzy one. According to Calvo, adaptations are stereotyped, genetically encoded, and reactive, always producing the same response to a stimulus and not subject to modification by different circumstances, however even some of the most prosaic plant behaviors, such as extending roots toward more moist soil can be altered by different conditions. The climbing behaviors of plant tendrils can be described as exploratory searches for suitable objects around which to entwine themselves. Different plants have preferences for the size and color of the objects their tendrils choose as targets. If their target is moved, the tendrils will begin searching and, if possible, locate its new whereabouts and begin climbing anew. Although some plants use circular or ellipsoid motion of the tendrils in their searches, sometimes a plant that has already placed tendrils around a support will cut short a different tendril’s search and go straight to the target instead of using a more circuitous, exploratory route, as though it has learned from his predecessors. This appears to be flexible learning and decision making at work. But what is going on inside the plant that directs such behavior?

When a plant looks as if it’s making a plan based on an internal map, and seems to be making decisions to alter in plan in the face of obstacles, does this require a directing mind to guide the behavior? I am reminded of Peter Robin Heisinger’s statement, “We now have overwhelming evidence that there is no such thing as irreducible complexity in evolved biological structures. Rather, we are dealing with our own brain’s irreducibly failed intuition” (Heisinger, 2021). It seems to me that Paco Calvo is prone to assuming that complicated plant behaviors must require a mind to direct them, because such complicated actions could not have been programmed into the plant via its genes. But is that true?

Putting together an animal’s physical structure is complicated. The cells that make up the growing body are sensitive to nutrients, toxins, sights and sounds and a variety of early experiences. One of the most complicated processes in growing a human body is assembling a working brain from the growth of billions of individual neurons. No two brains are alike, because as neurons grow, they interact with the idiosyncrasies of the experiences of the organism that houses them. Their growth is determined by genes, but the genes produce a modifiable plan, and the elements that can modify it affect the selection of the genes that control the neuron’s growth, so that it looks as if it has a mind. A neuron doesn’t have a mind and is not, by itself conscious. It grows by following an algorithm that allows it to modify its growth pattern according to the circumstances of its owner’s experiences (Heisinger, 2021). Probably, roots follow similar genetically based algorithms and the tendrils of vines do also. Those algorithms were chosen because they produced a plant that was likely to survive in a certain environment. The plant itself doesn’t need to know what it’s doing to survive. Its components just need to follow a plan that was shaped by evolution.

I’m a skeptic and I have biases. In my opinion, the author of Planta Sapiens has leapt into the gap formed by our lack of knowledge of how and why plants do what they do and inserted an assumption that would fit a cognitive being. I don’t think that’s merited, although that doesn’t mean it isn’t correct. My bias is to limit minds and consciousness to more complicated, brain-possessing creatures. But I may be anthropomorphizing, because when I think of a mind, I think of a human mind, and, as Calvo reminds us, there’s no reason to think that, if a plant had a mind, it would resemble a human one in any way we can think of. Arthur Reber makes a strong argument for even single-cell creatures being aware of what impinges on them from their environment, that is, having something akin to sensations. If he’s right, then perhaps even plants are aware of some parts of their environment and can sense when it impinges upon them. Depending on what we mean by “sense,” that could mean they are conscious. I don’t think so, but Calvo has at least opened my mind to the idea.

References

Dorman, C. (2023). Genius in Your Garden. A Review of Stefano Mancuso’s “The Revolutionary Genius of Plants.” https://caseydorman.com/the-genius-in-your-garden/

Heisinger, P.R. (2021). The Self-Assembling Brain: How Neural Networks Grow Smarter. Princeton, N.J. Princeton University Press.

Koch, C. (2015). The Feeling of Life Itself: Why Consciousness is Widespread but Can’t be Computed. Cambridge, MA: MIT Press.

Mancuso, S. (2018). The Revolutionary Genius of Plants: A New Understanding of Plant Intelligence and Behavior. New York: Atria Books.

Reber, A.S. (2018). The First Minds: Caterpillars, Karyotes and Consciousness. London: Oxford University Press.

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I appreciate this author's enthusiasm for studying the many interesting behaviors of plants, but unfortunately, this book wasn't written very well. It's a strange mix of personal anecdotes that are only tangentially related to the main topics, lengthy jokes that fall flat (they really aren't funny at all), and overly technical descriptions that are difficult for laypeople to understand.

The structure of the book also strikes me as very...unfocused. It seems to jump around randomly from point to point, round back on the same topic multiple times, describe the same idea numerous times in slightly different ways, etc. I felt like I was retreading the same ground chapter after chapter without ever quite reaching any real conclusions.

In short, this was a letdown for me. I really did want to learn about complex plant behaviors and the idea of plant intelligence, but this book didn't work for me.

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"An astonishing window into the inner world of plants, and the cutting-edge science in plant intelligence". A very accurate way to describe this thought provoking book. I greatly appreciate any book based on evidence based science, but Calvo adds in the passion behind why scientists and researchers study what they do, making me appreciate this book even more. With an undergraduate degree in psychology, I am well aware of humans (and animals) thought processes, levels of consciousness, and adaptivity to an ever changing world. This book changed my view of plants and how they can have just as much power of thought as us. I genuinely enjoyed reading this book; it was an easy to read novel on a fascinating topic!

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