When botanists go bad

Or at least get angry. These particular botanists are upset about the idea that plants could be conscious and have written an angry letter explaining why.

Taiz told the Guardian: “Our criticism of the plant neurobiologists is they have failed to consider the importance of brain organisation, complexity and specialisation for the phenomenon of consciousness.” 

The broadside drew a robust response from the University of Sydney’s Monica Gagliano, who conducts research on the cognitive abilities of plants, including perception, learning, memory and consciousness. She said the criticisms failed to take account of all the evidence and focused only on work that supported the authors’ viewpoint. “For me, the process of generating knowledge through rigorous science is about understanding the evidence base behind a claim,” she said. “Where is their experimental data? Or are we expected to just accept their claim at face value?”

I read the original letter (it's not long) and I think it's got some good and bad aspects. There's a lengthy discussion as to whether plants have similar structures to animal brains, but I think that's all somewhat immaterial; we have not yet established what consciousness is or how it arises. They comment on that fascinating experiment supposedly demonstrating that plants can learn, but all they say is :

However, Biegler has cautioned that such a conclusion is premature and that additional controls are required to establish the specificity of the response as well as to definitively rule out the effects of sensory adaptation and motor fatigue.

Which amounts to saying little more than that the result could be wrong, or that they simply don't believe the result.

They comment more extensively on an experiment designed to test whether plants can have conditioned responses, in which plants were apparently "trained" to grow towards the direction of a fan by combining it with blue light. They say this may be only a statistical artifact caused by the use of a maze to direct the plants, but they cite only a personal communication in support of an experiment using "more stringent conditions", so we can't know from this which authors actually ran the better experiment.

Next they address the interesting observation that anaesthetics have similar motion-suppressing effects on plants as animals. Here they seem on much firmer ground, claiming that this could be due to, well, motion-suppressing effects, which in no way implies the necessity of consciousness.

The remainder of the letter is given over to describing how consciousness could arise in animals given a sufficient level of physiological complexity. I didn't find it at all convincing - how could we ever know what's conscious and what isn't ? A far better discussion can be found in Other Minds, which looks at octopus intelligence (which I'll get around to reviewing properly at some point). That book does a good job of showing that while the octopus is probably not as intelligent as some urban myths might suppose, it probably is a basically intelligent, self-aware animal.

Here it seems to me that they take for granted the idea that consciousness requires complexity. Perhaps this is so, but I think they've missed the point of the "hard problem". Consciousness is a distinctly non-physical phenomenon : my imaginings have no physical substance; the electrochemical flows in my brain are not at all the same as my perceptions of imaginary giraffes. So is complexity really required ? Why can't rocks and electrons be conscious, after a fashion ? I'm not saying that they actually are, of course, just that both the ideas that consciousness derives from physics and that consciousness has nothing to do with physics seem to have severe problems.

Group of biologists tries to bury the idea that plants are conscious

The gardening gloves are off. Frustrated by more than a decade of research which claims to reveal intentions, feelings and even consciousness in plants, more traditionally minded botanists have finally snapped. Plants, they protest, are emphatically not conscious.