Planta Sapiens by Paco Calvo review – extraterrestrials in the garden: In Denis Villeneuve’s 2016 movie Arrival the US army asks an expert in linguistics to decipher the complex language of the seven-limbed aliens (“heptapods”) who have landed on Earth. It’s a memorable and indeed moving attempt to portray the immense challenges involved in bridging the gulf of mutual incomprehension between two completely different species.
I thought of Arrival while reading Paco Calvo’s remarkable book, the result of “two decades of passionate exploration into a rich and alternate world that exists alongside our own” – the world of plants. The subject of his exploration is startlingly radical: the question of whether plants can be regarded as possessing intelligence.
Calvo is a professor of the philosophy of science in the Minimal Intelligence Laboratory at the University of Murcia, Spain. Although he presents detailed scientific evidence to support his case, he also draws on philosophical arguments about the nature of consciousness. We humans have a tendency to believe that the world revolves around us, but Calvo writes that intelligence is “not quite as special as we like to think”.
He argues that it’s time to accept that other organisms, even drastically different ones, may be capable of it. Darwin has clearly been a guiding presence in Calvo’s attempt to open up a new frontier in science. In the course of his book, Calvo describes many experiments that reveal plants’ remarkable range, including the way they communicate with others nearby using “chemical talk”, a language encoded in about 1,700 volatile organic compounds. He also shows how, like animals, they can be anaesthetised.
In lectures, he places a Venus flytrap under a glass bell jar with a cotton pad soaked in anaesthetic. After an hour the plant no longer responds to touch by closing its traps. Tests show the plant’s electrical activity has stopped. It is effectively asleep, just as a cat would be. He also notes that the process of germination in seeds can be halted under anaesthetic. If plants can be put to sleep, does that imply they also have a waking state? Calvo thinks it does, for he argues that plants are not just “photosynthetic machines” and that it’s quite possible that they have an individual experience of the world: “They may be aware.”