Plants, people, and decision-making


Laura Ruggles writes:

Plants are not simply organic, passive automata. We now know that they can sense and integrate information about dozens of different environmental variables, and that they use this knowledge to guide flexible, adaptive behaviour.

For example, plants can recognise whether nearby plants are kin or unrelated, and adjust their foraging strategies accordingly. The flower Impatiens pallida, also known as pale jewelweed, is one of several species that tends to devote a greater share of resources to growing leaves rather than roots when put with strangers – a tactic apparently geared towards competing for sunlight, an imperative that is diminished when you are growing next to your siblings. Plants also mount complex, targeted defences in response to recognising specific predators. The small, flowering Arabidopsis thaliana, also known as thale or mouse-ear cress, can detect the vibrations caused by caterpillars munching on it and so release oils and chemicals to repel the insects.

Plants also communicate with one another and other organisms, such as parasites and microbes, using a variety of channels – including ‘mycorrhizal networks’ of fungus that link up the root systems of multiple plants, like some kind of subterranean internet. Perhaps it’s not really so surprising, then, that plants learn and use memories for prediction and decision-making.

Can plants make decisions?

A lot of people will balk at such a notion for obvious reasons. For instance, the idea of plants as decision-makers suggests the possibility of some plants making good decisions, others bad, and some suffering from indecisiveness.

Isn’t what is being presented as a decision, simply the outcome of a particular constellation of factors that result in a particular outcome? In which case the outcome is determined and involves no decision.

Maybe, but let’s flip this around and instead of questioning a posited decision-making process inside plants, consider what happens inside humans.

My favorite way of doing this is by attempting to zero in on the moment an action is initiated — the moment, for instance, when one decides to stand up from sitting.

Within the general field of awareness, there will probably be a phase of rumination and some physical precursors of action, but the exact moment in which the action starts — that seems to come out of nowhere. We function more like puppets animated by an invisible puppeteer and then mask our lack of agency with a narrative of purpose, after the fact.

Not sure about the agentless nature of physical action? Then consider this: what’s the next thought that will pop into your head?

Of course, we never actually know what’s going to arrive before it gets delivered. The brain offers no tracking service like Amazon.