Tuesday, April 1, 2014

Plant intelligence and plant aesthetics

This is a followup on my last post on plant aesthetics. Michael Pollan's New Yorker article "The Intelligent Plant: Scientists debate a new way of understanding flora" here lends support to the idea that plants may have aesthetic experiences.  Pollan begins his article with a mention of a book from the 1970s called The Secret Life of Plants which was intriguing at the time but also not very scientific.  Recent work in plant behavior and plant "intelligence" has been much more impressive and interesting.  Assuming that intelligence is an emergent capacity, it is arguable that perception of aesthetic qualities or the having of aesthetic experiences is also possible for plants.  I use the word "possible" advisedly here: we do not as yet have any strong reason to believe that plants can have aesthetic experiences.  But the idea is intriguing.  The claim being made by a group of six contemporary biologists (in an article from 2006 supporting a new field called plant neurobiology) is that (to quote from Pollan) "the sophisticated behaviors observed in plants cannot at present be completely explained by familiar genetic and biochemical mechanisms. Plants are able to sense and optimally respond to so many environmental variables—light, water, gravity, temperature, soil structure, nutrients, toxins, microbes, herbivores, chemical signals from other plants—that there may exist some brainlike information-processing system to integrate the data and coördinate a plant’s behavioral response.."  and "electrical and chemical signalling systems have been identified in plants which are homologous to those found in the nervous systems of animals."  The usual claim by opponents to plant intelligence (and thus plant aesthetics) is that plants have no nervous system and hence cannot be intelligent, conscious or have aesthetic experiences.  But isn't this just an a priori argument?  It assumes that intelligence requires a nervous system and then automatically exclude plants because they have no nervous system, even though we can talk about plants communicating and behaving in many other animal-like ways.  If you have behavior that "looks very much like learning, memory, decision-making, and intelligence" then why not behavior that looks very much like the experience of beauty? 

To be sure, Pollan also observed that no one he spoke to who supported plant intelligence supports the idea of plant emotions.  One could say that although intelligence may be there, aesthetics is a matter of emotional response and hence is beyond the realm of plants.  However, supporters of plant intelligence have also argued to the idea that plants can experience something like pain and that they can behave in ways that favor their own relatives over others.  So, if plant intelligence is conceivable, so too may be plant emotions.

The problem is that we may have just been looking for brains in individual plants:  and there are none.  However, it might be that both intelligence and aesthetic experience emerges at a level above that of the individual:  "intelligence in plants resembles that exhibited in insect colonies, where it is thought to be an emergent property of a great many mindless individuals organized in a network."  Perhaps, as Pollan suggests, there are ways of getting brainy behavior without actual brains.

Of course you do not have aesthetics is you have no senses, but the claim made by scientists like Stefano Mancuso is, as Pollan puts it "Plants have evolved between fifteen and twenty distinct senses, including analogues of our five: smell and taste (they sense and respond to chemicals in the air or on their bodies); sight (they react differently to various wavelengths of light as well as to shadow); touch (a vine or a root “knows” when it encounters a solid object); and, it has been discovered, sound."  Pollan notes that Heidi Appel, a chemical ecologist, found in a recent experiment that a recording of a caterpillar eating a leaf can prime a plant to produce defensive chemicals.  Moreover, "the tips of plant roots, in addition to sensing gravity, moisture, light, pressure, and hardness, can also sense volume, nitrogen, phosphorus, salt, various toxins, microbes, and chemical signals from neighboring plants. Roots about to encounter an impenetrable obstacle or a toxic substance change course before they make contact with it."

Aesthetics also requires choice (this wine is better than that, and so I choose the better one), but do plants choose?  Mancuso argues that they do.  Pollan writes "A dodder vine will 'choose' among several potential hosts, assessing, by scent, which offers the best potential nourishment. Having selected a target, the vine then performs a kind of cost-benefit calculation before deciding exactly how many coils it should invest—the more nutrients in the victim, the more coils it deploys. I asked Mancuso whether he was being literal or metaphorical in attributing intention to plants."  His answer implied that he did.

Again, to have aesthetic experience one must be conscious.  If, by consciousness, one means "the state of being awake and aware of one’s environment" then Mancuso and František Baluška argue that plants can be conscious: “The bean knows exactly what is in the environment around it,” Mancuso said. “We don’t know how. But this is one of the features of consciousness: You know your position in the world. A stone does not.”  Pollan writes further, "in support of their contention that plants are conscious of their environment, Mancuso and Baluška point out that plants can be rendered unconscious by the same anesthetics that put animals out: drugs can induce in plants an unresponsive state resembling sleep. (A snoozing Venus flytrap won’t notice an insect crossing its threshold.)" 

But again, in order to have aesthetic experience you must be able to feel pleasure and pain.  Can plants feel pain?  Mancuso and Baluska argue yes, although they carefully call it "plant specific pain perception."  If plants can experience pain then why not pleasure as was argued by Fechner?

What about the arguments against plant intelligence?  Lincoln Taiz, a plant physiologist at U.C. Santa Cruz said to Pollan that “the mechanisms are quite different from those of true nervous systems” and that plant neurobiologists suffer from “over-interpretation of data, teleology, anthropomorphizing, philosophizing, and wild speculations.” He thinks plant behavior will ultimately be explained by "the action of chemical or electrical pathways, without recourse to “animism.”"  Yet it is granted already that the mechanisms are quite different from animal nervous systems.  Moreover, when Taiz makes his reductionist assumptions he is philosophizing and speculating every bit as much as his opponents.  Moreover, it has long been argued by reductionist materialists that this is true for humans as well: and so Taiz's argument seems too strong for its purpose, "too strong" in the sense of too general.  That is, his argument just is the same argument materialists have used traditionally to attempt to reduce human consciousness.  Perhaps this will turn out to be the correct position and aesthetics itself will be reduced to chemistry, but this is no special argument against plant aesthetics.  If Taiz thinks that "animism" is the sin of applying the correct notion of the human soul to animals he is just inconsistent.

So, given that arguments set forth in my previous post and the additional work done by scientists like Mancuso I would argue that it is quite possible that there is such a thing as plant aesthetics.   

Interested in learning more?  See my book:  Thomas Leddy The Extraordinary in the Ordinary:  The Aesthetics of Everyday Life.  Broadview Press, 2012.  Available at Amazon in paperback, and an electronic version at google where you can also find most of the first 47 pages including the table of contents.  You can also buy it fro  Broadview. 

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