Book Reviews - Review 369

Plants respond to light, odour molecules, gravity and electricity. Does this imply that they have senses, or even that they possess a rudimentary form of consciousness?

The title of this book, and its chapter headings - "What a Plant Sees", "What a Plant Feels", "The Aware Plant" etc. - very much suggest that they do. There are interesting descriptions of the biochemical mechanisms by which plants seek light, detect when they are injured, receive information about disease in neighbouring plants, and discern up from down.

The excited reader embarks on this book anticipating cutting-edge revelations about plant sentience, or at least a remodelling of our relationship with simpler life forms. Yet while the technical detail of the book is fascinating, when Chamovitz steps back to look at the bigger picture, he goes all coy. Having liberally cast about the words "see", "smell", "feel" and "aware" throughout the book, he backtracks at the notion that brainless organisms might have qualitative subjective experiences. At least, I think he does - but it's hard to tell because his language is ambiguous. He derides

Yet just a page earlier he has stated, "Plants are acutely aware of the world around them". If that's not anthropomorphism, what is? He goes on to write,

How do we know anything about the sensual experiences of plants, or how they might have sensual experiences at all without brains? Chamovitz glosses over these questions, despite having cited research that "shows that these [glutamate] receptors in plants function in cell-to-cell signalling in a way that's very similar to how to how human neurons communicate with each other". On the one hand, "Perhaps the similaties between human brain function and plant physiology may be greater than we've assumed"; on the other, "plants do not suffer". Following hints of a radical rethinking of the electrochemical basis of consciousness, the book drops the subject and moves on.

My feeling is that Chamovitz chose unorthodox anthropomorphic terms to attract publicity and a wide lay readership to the book, then adopted a stance of "I didn't mean that at all" out of consideration for his scientific reputation. What a Plant Knows reaches out for the boundary between science and philosophy, yet draws back whenever its speculations approach the controversial.