The Revolutionary Genius of Plants A New Understanding of Plant Intelligence and Behavior

In an earlier review, I said that botany was never my greatest love. With The Revolutionary Genius of Plants, Italian plant neurobiologist Stefano Mancuso does a very good job of changing my mind. In the preface, he implores readers to imagine what it is like to be a plant, unable to escape predators. How can you survive this onslaught? The answer: by becoming virtually indestructible. And the way plants do this is by having a body plan that is almost the inverse of animals. There was something so powerful about Mancuso’s writing here that he instantly drew me in.

Plants have long been considered as the vegetal backdrop to our lives. Green, immobile, and fairly boring. Sure, photosynthesis and all that, but plants are, well, nothing like animals. Or are they? In recent years, a growing number of scientists are making the case that plants are surprisingly intelligent and possess senses similar to our own; smell, touch, hearing, memory, even awareness.

Mancuso has been hailed as the founder of the discipline of plant neurobiology and has written previously on this subject in Brilliant Green. The current book originally appeared in Italian in 2017. Similarly, there have been popular science books such as What a Plant Knows, more serious works such as Plant Sensing and Communication, and even a textbook: Plant Behaviour & Intelligence.

I have always been a bit sceptical of this. Recently, the German forester Peter Wohlleben has enjoyed a huge commercial success with his book The Hidden Life of Trees, which has been criticised by scientists for its selective and unrepresentative sources. And I feel this is just the top of the slippery slope into pseudoscience. The New Age movement has happily appropriated traditional knowledge of indigenous tribes, both their use of plant parts for medicinal purposes, and the use of psychoactive botanical substances such as ayahuasca by shamans. And before you know you are dabbling in vision quests, spiritual healing, forest bathing and the secret teachings of plants. Critics might argue that, as a sceptic not moving in these circles nor intending to, I have no idea what I am talking about and am belittling their profound experiences and beliefs. Well, sorry, but I smell a rat, and I will get back to this topic in a future review of The Ethnobotany of Eden.

Fortunately, Mancuso does much to quell my scepticism and shows that, for those who can set aside their prejudices, there is a lot of serious science to be done. As I mentioned above, what makes plants so hard for us to grasp is that their body plan is the inverse of ours. Where animals concentrate functionality in specialised organs, plants distribute the same functions throughout their whole body in a diffuse fashion. And this is such a profound difference that we struggle to understand plants.

Mancuso introduces experimental work showing that certain plants have a form of memory, with touch-sensitive plants rapidly learning to ignore stimuli that are not dangerous. Others show extraordinary forms of mimicry, or mimesis, that implies a form of vision. Root systems function as a form of distributed intelligence or a collective brain, allowing efficient exploration of soil for nutrients. By now most of us will have seen time-lapse footage in nature documentaries showing how plants move but do so on a different time scale to us. Other plants manipulate insects by secreting neuroactive substances. And Mancuso is not the first person to suggest that plants domesticated us as much as we domesticated them, though I feel he gets a bit carried away here. He suggests that vetch seeds evolving to resemble lentil seeds – and so piggy-back on human cultivation of lentils as a pest species – shows that plants are learning to respond to our preferences because the vetch plant does not want to be discarded. This might just be semantics, but I feel this ascribes agency to plants where a simple explanation of natural selection against vetch seeds not resembling lentil seeds would suffice. I have yet to be convinced that this means plants have learned something.

Towards the second half of the book, Mancuso switches to what we can learn from plants. Principles borrowed from plants have been used in structural engineering, but also the design of space probes that can passively move, dig and drill the same way certain plant seeds can. Similarly, salt-tolerant plants could help address the shortage of suitable agricultural land and usher in a future of marine farming to feed the growing human population.

As an object, The Revolutionary Genius of Plants is a very nicely designed, full-colour book. The short chapters feature plenty of colour photos (though a few are of such low resolution that they appear pixelated in print), and the quality of the paper stock makes for a hefty book. In many ways, it reminds me of the visually pleasing productions of, say, Ivy Press.

Mancuso keeps the science fairly light (though references are provided), dipping into a range of topics with the occasional tangent. The applied research of his group, which he mentions in various places, is certainly interesting. And well before the end of the book Mancuso had me convinced that plants are worth paying more attention to. Especially his claim that, despite lacking central organs, plants can achieve many of the same feats by distributing functionality throughout their bodies, making them so very alien to us, is made very convincingly. Although I am left with many questions as to how such things are achieved exactly, something this book does not dig into in too much detail, The Revolutionary Genius of Plants makes for a fascinating and entertaining entry point to the topic of plant intelligence and behaviour.