Can plants perceive?

Given the current COVID-19 situation, we’ve decided with our research group to meet twice a week (and not once as we used to) and have two different sessions: one in which someone of the group is presenting her/his research or a paper of interest for her/him (with some background/context included), and another in which we do a journal club altogether and each of us gives a ~10 min presentation of a paper (that could be free-themed or with a given theme that we all agreed).

So, this week we’ve started with this double-session of group meetings and today we had the journal club one. We’ve only had time to present three of us since we tend to discuss and have a wide debate on the topics we talk about. One of the papers we’ve briefly discuss today is about whether plants perceive or not accordingly to two papers.

Predicting green: really radical (plant) predictive processing

In this first paper, Calvo and Friston (2017) account for the way plants respond to salient features of their environment under the free-energy principle for biological systems. Their main hypothesis is that plant behavior takes place by way of a process (active inference) that predicts the environmental sources of sensory stimulation. They argue that this principle endows plants with a form of perception that underwrites purposeful and anticipatory behavior.

In the second paper, Taiz and colleagues reply to Calvo and Friston (2017)’s paper saying that plants do not have consciousness. They outlined a new hypothesis proposed by Feinberg and Mallat for the evolution of consciousness in animals. Based on a survey of the brain anatomy, functional complexity, and behaviors of a broad spectrum of animals, different criteria points were established for the emergence of consciousness. They found that the only animals that satisfied these criteria were the vertebrates (including fish), arthropods (e.g., insects, crabs), and cephalopods (e.g., octopuses, squids). In light of Feinberg and Mallat’s analysis, they consider the likelihood that plants, with their relative organizational simplicity and lack of neurons and brains, have consciousness to be effectively nil. To put it in other words, they claimed that since plants are not as complex as animals or they do not have neurons, then they cannot have consciousness.

From my point of view, I found plant neurobiology an interesting field that can help us to understand life and cognition more broadly. Also, from my (little and quasi-inexistent) knowledge on this topic, I would like to say that the “predictive processing story” sounds really appealing and natural for me and the “free-energy principle” for biological systems really makes sense in mind.

I invite you to read the two papers chronologically and debate with yourself whether you think plants have the ability to perceive and if you would consider that they have consciousness. But, first of all, I would try to disentangle the meaning of the words “perception” and “consciousness” based on your meaning and those appearing in the papers to assess that you’re on the same page.


Feature image from Pexels – C0 license.

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