The coming of the veggies

A week or so ago, the Guardian ran a story about the consciousness of plants (reference 1), prompted by the publication of a learned paper on this subject by Messrs. Taiz, Alkon and others, a paper which endeavours to put this subject firmly to bed, in the negative (reference 2).

It seems that this whole subject has been energised by a group of people who call themselves plant neurobiologists, some of whom look to make a good living on the public lecture circuit, perhaps cashing in on widespread and very understandable concern about the rape of the planet, global warming, mass extinctions and so on and so forth. This group, dubbed the PNP’s, the plant neurobiology proponents, has spawned another group, dubbed the PNO’s, the plant neurobiology opponents, amongst whom Taiz & Co. are ranged. With this clash of titans producing a respectable amount of noise.

The argument of the PNP’s, as reported in reference 2, rests mainly on the sophisticated signalling and computing systems developed by plants to manage their affairs. Some of this was touched on in the talk at the Royal Institution noticed at reference 3.

With the noise mentioned above including earnest debates about whether these systems amount to intelligence, knowledge or cognition. Rather sterile debates to my mind, with both concepts occupying a continuum – and if there are people who want to stick plants at one end of it, so what?

Then the PNP’s make much of the fact that activity in one part of a plant can affect activity in another part, action at a distance, with some of them going so far to talk of the root tips being the brains of a plant.

One PNP in particular, Monica Gagliano, claims to have demonstrated habituation and associative learning in plants, capabilities previously thought to be the preserve of animals. Claims which might well have been disputed but which caught the public eye and appear to have resulted in Gagliano being asked to give lots of talks. See reference 4.

They then go on to describe the adaptive responses of some plants to noxious stimuli as pain, from where it is only a short step to saying that plants experience pain and can be said to be conscious.

Feinberg & Mallatt

Although I had trouble with a lot of the paper at reference 5, I found the story there, more or less repeated by Taiz & Co., of the evolution of consciousness in higher animals, with lots of mobility, lots of senses and big brains, persuasive –  evolution which crucially involves being able to create complex, integrated images of both aspects of the self and aspects of not-self, that is to say the world outside. Hard to see how plants with their relatively limited sensory systems and their lack of a nervous system with any, never mind the millions of neurons thought necessary, are going to be able to manage the same trick.

The eighteenth century

Taiz and Co. go on to tell us something of eighteenth century, romantic speculations about the life of plants, speculations fuelled in part by a reaction from the dry, reductionist science of the likes of Newton. Speculations which lead smoothly enough to those of the PNP’s.

The speculations about the love life of plants which followed the discovery of their sexuality make a very entertaining story and produced prose which would not have disgraced one of the rather later novels by D. H. Lawrence. I think, for example, that ‘Women in Love’ contains some purple prose about the flowers of plants. While M. Proust, in his famous book about wasting time, got quite carried away by the goings on of orchids.

But pride of place goes to Erasmus Darwin, the botanist & physician grandfather of the more famous Charles Darwin, who, following and building on the work of his near contemporary Linnaeus, wrote an epic poem about the matter (reference 6), from which the snap above has been taken. A poem which was a best seller in its day and made the author a lot of money. It also seems that there were those who deplored this intrusion of sex into botany, which until that time had been seen as a suitable pursuit for young ladies, with all the other sciences, for some reason, being off limits.

I also learn of the complicated goings on among the pistils and stamens of flowers, matters which fascinated the lettered & leisured classes of the 18th century and which presumably involved something like the signalling noticed at reference 3. Plants might not be conscious but they certainly are complicated, certainly worthy of study. And that said, one can see how one might easily get carried away by analogy with humans, projecting all kinds of human stuff onto plants. Projections which are rather better justified in the case of monkeys, for which see reference 7.

An accessible account of Darwin’s poem can be found at reference 8.

While returning to the present paper, I quote:

‘… This new wave of Romantic biology appears to have been inspired by a justifiable concern about humanity’s continuing ecological degradation of the biosphere: the loss of habitats and biodiversity, the over-exploitation of natural resources, and the crisis of climate change …’.

A rather different motivation from that of Darwin and his friends.

Another quote

Along the way Taiz & Co. offer a striking quote from a book about bees by one Moritz (reference 9):

‘… as with any complex social system, honey bee societies are prone to error, robbery, cheating, and social parasitism. The honey bee colony is thus far from being a harmonious, cooperative whole. It is full of individual mistakes, obvious maladaptations and evolutionary dead ends. Conflict, cheating, worker inefficiency and curious reproduction strategies all occur …’.

One is tempted to buy the book, but I shall have to see.

Conclusions

I rest content with the conclusion of reference 2 that plants are not conscious. No need to spend any further time on the matter.

Also with those of reference 5. First, higher vertebrates are conscious and lower vertebrates and some arthropods may be. Second, this consciousness is the product of massive sensory input combined with massive brain power, brains powered by millions and billions of neurons.

The entertaining diversion into the 18th century was a bonus.

References

Reference 1: Group of biologists tries to bury the idea that plants are conscious – Ian Sample – 2019. The Guardian, 3rd July.

Reference 2: Plants Neither Possess nor Require Consciousness - Lincoln Taiz, Daniel Alkon, Andreas Draguhn, Angus Murphy, Michael Blatt, Chris Hawes, Gerhard Thiel, David G. Robinson – 2019.

Reference 3: http://psmv4.blogspot.com/2019/07/arabidopsis-thaliana.html.

Reference 4: https://www.monicagagliano.com/.

Reference 5: The nature of primary consciousness. A new synthesis – Todd E. Feinberg, Jon Mallatt – 2016.

Reference 6: The Loves of the Plants – Erasmus Darwin – 1789.

Reference 7: https://psmv4.blogspot.com/2019/06/monkey-life.html. A post which I have yet to follow up with the zoological detail.

Reference 8: Botany for Gentlemen: Erasmus Darwin and The Loves of the Plants – Janet Browne – 1989.

Reference 9: The Dark Side of the Hive: The Evolution of the Imperfect Honey Bee – Moritz, R.F.A. – 2018.

Reference 10: The Secret Life of Plants – Peter Tompkin – 1989. Seemingly, an early blast from the PNP’s, billed as a 'Fascinating Account of the Physical, Emotional, and Spiritual Relations Between Plants and Man'.