It’s a wild idea, but recent experiments suggest plants may have the ability to learn and make decisions. Are the claims true and if so, what does it mean for our understanding of consciousness and the human mind?
Life 24 August 2022
Antonio Sortino
MANY people have seen the way a Mimosa pudica plant, also called the touch-me-not, folds its leaves when they are touched. Fewer know that if you put one into a sealed chamber with a dose of anaesthetic, it will eventually stop doing this, as though it has been knocked out or put to sleep.
The anaesthetic needn’t be special. Diethyl ether, an old-school general anaesthetic, works well. Lidocaine, a local anaesthetic favoured by dentists, is also effective when applied at the roots. What’s more, if you attach electrodes to the surface of the leaves at the same time, you will see that the waves of electrical activity that usually spread through the plant’s tissues are suppressed. These effects aren’t confined to Mimosa pudica – all plants are probably susceptible to anaesthesia, it is just that the effects are more dramatic in fast movers like Mimosa plants and Venus flytraps.
Paco Calvo at the University of Murcia in Spain has done this trick several times in front of audiences. It never fails to surprise onlookers, prompting them to ask the very questions he himself is trying to answer. If plants can be “put to sleep”, does this mean they exist in a state of awareness that is shut off by anaesthetics? Might we consider this state to be a kind of sentience, a subjective internal experience? If so, do plants have some form of consciousness? These are controversial ideas, but Calvo and a small group of plant behaviour researchers take them seriously. Their findings so far, though tentative, could disrupt our understanding of consciousness – not to mention our attitudes towards plants.
Plants …