The Mental Life of Plants and Worms, Among Others

Studies of mental functions, behaviors and the nervous system.

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The Mental Life of Plants and Worms, Among Others

#1  Postby kennyc » Apr 07, 2014 12:39 pm

New York Review of Books.


The Mental Life of Plants and Worms, Among Others
Oliver Sacks

Charles Darwin’s last book, published in 1881, was a study of the humble earthworm. His main theme—expressed in the title, The Formation of Vegetable Mould through the Action of Worms—was the immense power of worms, in vast numbers and over millions of years, to till the soil and change the face of the earth. But his opening chapters are devoted more simply to the “habits” of worms.

Worms can distinguish between light and dark, and they generally stay underground, safe from predators, during daylight hours. They have no ears, but if they are deaf to aerial vibration, they are exceedingly sensitive to vibrations conducted through the earth, as might be generated by the footsteps of approaching animals. All of these sensations, Darwin noted, are transmitted to collections of nerve cells (he called them “the cerebral ganglia”) in the worm’s head.

“When a worm is suddenly illuminated,” Darwin wrote, it “dashes like a rabbit into its burrow.” He noted that he was “at first led to look at the action as a reflex one,” but then observed that this behavior could be modified—for instance, when a worm was otherwise engaged, it showed no withdrawal with sudden exposure to light.

For Darwin, the ability to modulate responses indicated “the presence of a mind of some kind.” He also wrote of the “mental qualities” of worms in relation to their plugging up their burrows, noting that “if worms are able to judge…having drawn an object close to the mouths of their burrows, how best to drag it in, they must acquire some notion of its general shape.” This moved him to argue that worms “deserve to be called intelligent, for they then act in nearly the same manner as a man under similar circumstances.”

...
It was shown within a few years of Darwin’s death that even single-cell organisms like protozoa could exhibit a range of adaptive responses. In particular, Herbert Spencer Jennings showed that the tiny, stalked, trumpet-shaped unicellular organism Stentor employs a repertoire of at least five different responses to being touched, before finally detaching itself to find a new site if these basic responses are ineffective. But if it is touched again, it will skip the intermediate steps and immediately take off for another site. It has become sensitized to noxious stimuli, or, to use more familiar terms, it “remembers” its unpleasant experience and has learned from it (though the memory lasts only a few minutes). If, conversely, Stentor is exposed to a series of very gentle touches, it soon ceases to respond to these at all—it has habituated.
.....
We often think of insects as tiny automata—robots with everything built-in and programmed. But it is increasingly evident that insects can remember, learn, think, and communicate in quite rich and unexpected ways. Much of this, doubtless, is built-in—but much, too, seems to depend on individual experience.
...


Much More here:
http://www.nybooks.com/articles/archive ... insrc=hpma
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Re: The Mental Life of Plants and Worms, Among Others

#2  Postby DavidMcC » Apr 07, 2014 4:04 pm

Perhaps Oliver is a little over-impressed by what natural selection can achieve without a brain (and therefore without a "mental life", AFAIAC).
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Re: The Mental Life of Plants and Worms, Among Others

#3  Postby kennyc » Apr 07, 2014 4:10 pm

He is something of an 'excitable boy' :D
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Re: The Mental Life of Plants and Worms, Among Others

#4  Postby Sendraks » Apr 07, 2014 4:15 pm

Somebody page pl0bs, he'd freaking love this.
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Re: The Mental Life of Plants and Worms, Among Others

#5  Postby DavidMcC » Apr 07, 2014 4:21 pm

Sacks is not the only one to exaggerate the mental powers of simple animals. Worms leave trails behind them, that obviate the need to memorize their path in detail. Most ants do something similar, but have the advantage of living in a colony, which effectively makes the important decisions for them (using "distributed intelligence"). Desert ant foraging behaviour is a good example:

NCBI paper: Re-Visiting of Plentiful Food Sources and Food Search Strategies in Desert Ants
This paper does not even mention that the ants live in a colony, and attributes all the skills involved to each individual ant. Big mistake! Only some of skills involved can be put down to the lone ant.
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Re: The Mental Life of Plants and Worms, Among Others

#6  Postby Mr.Samsa » Apr 07, 2014 10:33 pm

Sacks' article was quite brilliant but I wish he had gone into more detail in the recent research into plant neurobiology and the modern criticisms of the assumption that complex behaviors require a brain.
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Re: The Mental Life of Plants and Worms, Among Others

#7  Postby Animavore » Apr 07, 2014 11:50 pm

Mr.Samsa wrote: plant neurobiology


Tell me more.
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Re: The Mental Life of Plants and Worms, Among Others

#8  Postby Mr.Samsa » Apr 08, 2014 12:31 am

Animavore wrote:
Mr.Samsa wrote: plant neurobiology


Tell me more.


I think there has been a thread on this topic before but there are some good articles here:

Aspects of Plant Intelligence

Plant neurobiology: an integrated view of plant signaling

Historical Overview on Plant Neurobiology

The interesting thing about the debate over the area of plant neurobiology is not the concepts they discuss; that is, there is no controversy that the findings they present are evidence-based and factual. The only debate is over semantics, whether it is accurate to refer to this kind of processing as "neurobiology" and I think there are good arguments for and against it.
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Re: The Mental Life of Plants and Worms, Among Others

#9  Postby Deremensis » Apr 08, 2014 3:15 am

I saw the title of this topic and was absolutely sure it was another pl0bs post. Oh well.

As always, I'm very skeptical of the word choice when we refer to the adaptive behaviors of plants and comparatively basic life forms. Just because something has evolved an automated response to something does not mean it "thinks" per-se. You can have some VERY complex automated responses - as evidenced by increasingly complex computer programs and simulations - without having "intelligence". One aspect of intelligence, out of many, is, I believe, the ability to formulate brand new responses WITHOUT having those responses be an evolved response. The article's described responses don't seem very much like intelligence to me based on this factor alone.

To be clear, I don't think that's any reason to devalue the complexity and beauty of such evolved systems and what we can learn from them. However, such distinctions as the one I'm making are important to make. I, for one, would be very excited by conclusive proof that plants are intelligent in the same manner that many higher animals are. I just haven't seen the evidence for it yet.
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Re: The Mental Life of Plants and Worms, Among Others

#10  Postby Teuton » Apr 08, 2014 5:19 am

kennyc wrote:
The Mental Life of Plants and Worms, Among Others
Oliver Sacks
…Worms can distinguish between light and dark, and they generally stay underground, safe from predators, during daylight hours. They have no ears, but if they are deaf to aerial vibration, they are exceedingly sensitive to vibrations conducted through the earth, as might be generated by the footsteps of approaching animals. All of these sensations, Darwin noted, are transmitted to collections of nerve cells (he called them “the cerebral ganglia”) in the worm’s head.…


Physiological sensitivity, i.e. mere behavioral responsitivity or reactivity to external stimuli, is not the same as psychological sentience. The former is consciousness/experience-independent, and the latter is not. Sentient beings are beings which (are able to) undergo subjective experiences such as sensations (e.g. visual impressions); and sensitive beings aren't per se sentient beings. Physiological sensitivity is a necessary but no sufficient condition for sentience.

"Worms can distinguish between light and dark." – This is ambiguous between "Worms can react differently to light and dark, but they do so unconsciously" and "Worms have conscious visual impressions of light and dark, and can react accordingly". Worms might be sentient or conscient beings, but the mere fact that worms react differently to different optic stimuli doesn't prove they really are.
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Re: The Mental Life of Plants and Worms, Among Others

#11  Postby Teuton » Apr 08, 2014 5:37 am

"We and all higher animals are bilaterally symmetrical, have a front end (a head) containing a brain, and a preferred direction of movement (forward). The jellyfish nervous system, like the animal itself, is radially symmetrical and may seem less sophisticated than a mammalian brain, but it has every right to be considered a brain, generating, as it does, complex adaptive behaviors and coordinating all the animal’s sensory and motor mechanisms. Whether we can speak of a “mind” here (as Darwin does in regard to earthworms) depends on how one defines “mind.”

It is fascinating to think of Darwin, Romanes, and other biologists of their time searching for “mind,” “mental processes,” “intelligence,” even “consciousness” in primitive animals like jellyfish, and even in protozoa. A few decades afterward, radical behaviorism would come to dominate the scene, denying reality to what was not objectively demonstrable, denying in particular any inner processes between stimulus and response, deeming these as irrelevant or at least beyond the reach of scientific study."


(Oliver Sacks: http://www.nybooks.com/articles/archive ... insrc=hpma)

Only bilateral animals have a central nervous system (CNS), and having a CNS is arguably a necessary condition for having consciousness. The most primitive CNS is in fact found in worms, and I don't deny that there might well be such a phenomenon as worm consciousness or insect consciousness. But I do deny that non-bilateral animals lacking a CNS such as jellyfish are conscient beings. And I strongly deny that plants are conscient beings.
Moreover, I uphold and defend the following principle:
Nothing has a mind unless it has consciousness: nonconscient beings are nonminded beings (beings without mental properties).

But, of course, if for a living being (animal or plant) to have a mind is simply for it to have a (neuro-)physiological internal input/output processor guiding and adapting its behavior, then minds are consciousness-independent. However, in this case it's far from clear what's genuinely mental about unconscious minds. My answer is: nothing!
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Re: The Mental Life of Plants and Worms, Among Others

#12  Postby Teuton » Apr 08, 2014 6:03 am

Mr.Samsa wrote:Sacks' article was quite brilliant but I wish he had gone into more detail in the recent research into plant neurobiology and the modern criticisms of the assumption that complex behaviors require a brain.


Plants don't contain nerve cells, do they? So there is no plant neurobiology.
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Re: The Mental Life of Plants and Worms, Among Others

#13  Postby Mr.Samsa » Apr 08, 2014 8:29 am

Deremensis wrote:I saw the title of this topic and was absolutely sure it was another pl0bs post. Oh well.

As always, I'm very skeptical of the word choice when we refer to the adaptive behaviors of plants and comparatively basic life forms. Just because something has evolved an automated response to something does not mean it "thinks" per-se. You can have some VERY complex automated responses - as evidenced by increasingly complex computer programs and simulations - without having "intelligence". One aspect of intelligence, out of many, is, I believe, the ability to formulate brand new responses WITHOUT having those responses be an evolved response. The article's described responses don't seem very much like intelligence to me based on this factor alone.

To be clear, I don't think that's any reason to devalue the complexity and beauty of such evolved systems and what we can learn from them. However, such distinctions as the one I'm making are important to make. I, for one, would be very excited by conclusive proof that plants are intelligent in the same manner that many higher animals are. I just haven't seen the evidence for it yet.


I think one of the disappointing parts of the article was exactly that it only discussed simple reflexive behaviors even though, for example, the worms discussed are capable of more than just basic classical conditioning.

Teuton wrote:
Mr.Samsa wrote:Sacks' article was quite brilliant but I wish he had gone into more detail in the recent research into plant neurobiology and the modern criticisms of the assumption that complex behaviors require a brain.


Plants don't contain nerve cells, do they? So there is no plant neurobiology.


"Researchers began to investigate easily stainable intracellular plasma strands that run across the lumen of many plant cells, and sometimes even continue over several cells for their potential role as nerve-like, excitation-conducting structures. Such strands were shown to occur in traumatized areas of many roots54 and in insectivorous butterworts where they connect the glue-containing hair tips with the basal peptidase-producing glands of the Pinguicula leaves.55–56 However, after investigating these claims, Haberlandt came to the conclusion that the only nerve-like structures of plants were situated the long phloem cells of the vascular bundles.7–8 From that time on papers, lectures and textbooks reiterated statements that “plants have no nerves”.

This unproductive expression ignores the work of Darwin, Haberlandt, Pfeffer and Bose together with the fact that in spite of their anatomical differences, nerve cell networks and vascular bundles share the analog function of conducting electrical signals. Similar anatomical differences have not been an obstacle to stating that both plants and animals consist of cells. The mechanistic similarity of excitations (consisting of a transient decline in cell input resistance) in plant and nerve cells was later elegantly demonstrated by the direct comparison of action potentials in Nitella and the giant axon of squids.57–58 Today, consideration of nerve-like structures in plants involves increasingly more aspects of comparison. We know that many plants can efficiently produce electric signals in the form of action potentials and slow wave potentials (= variation potentials) and that the long-distance propagation of these signals proceeds in the vascular bundles. We also know that plants like Dionea can propagate APs with high efficiency and speed without the use of vascular bundles, probably because their cells are electrically coupled through plasmodesmata. Other analogies with neurobiology include vesicle-operated intercellular clefts in axial root tissues (the so-called plant synapses)59 as well as the certain existence and operation of substances like neurotransmitters and synaptotagmins in plant cells (e.g., refs. 60 and 61). The identification of the role(s) of these substances in plants will have important implications. Altogether, modern plant neurobiology might emerge as a coherent science.62"


[From: "Historical Overview on Plant Neurobiology" linked above].
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Re: The Mental Life of Plants and Worms, Among Others

#14  Postby Mr.Samsa » Apr 08, 2014 8:46 am

Whoops, I can't believe I missed this comment from Sacks (thanks to Teuton for quoting it otherwise I would've missed it):

It is fascinating to think of Darwin, Romanes, and other biologists of their time searching for “mind,” “mental processes,” “intelligence,” even “consciousness” in primitive animals like jellyfish, and even in protozoa. A few decades afterward, radical behaviorism would come to dominate the scene, denying reality to what was not objectively demonstrable, denying in particular any inner processes between stimulus and response, deeming these as irrelevant or at least beyond the reach of scientific study.


This is a poor understanding of history and behaviorism. What Sacks seems to be attempting to describe is in fact John Watson's methodological behaviorism, not Skinner's radical behaviorism. More importantly, even methodological behaviorism didn't deny inner processes but rather (as he notes) they were ignored at the time as there was no scientific way to study them.

Radical behaviorism, on the other hand, was a rejection of methodological behaviorism. It argued that not only can inner processes be studied scientifically but that for psychology to be a science then it must study inner processes.
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Re: The Mental Life of Plants and Worms, Among Others

#15  Postby kennyc » Apr 08, 2014 10:48 am

Here's a piece from The New Yorker:


THE INTELLIGENT PLANT Scientists debate a new way of understanding flora.
BY MICHAEL POLLAN
DECEMBER 23, 2013

Plants have electrical and chemical signalling systems, may possess memory, and exhibit brainy behavior in the absence of brains.Plants have electrical and chemical signalling systems, may possess memory, and exhibit brainy behavior in the absence of brains. Construction by Stephen Doyle.

In 1973, a book claiming that plants were sentient beings that feel emotions, prefer classical music to rock and roll, and can respond to the unspoken thoughts of humans hundreds of miles away landed on the New York Times best-seller list for nonfiction. “The Secret Life of Plants,” by Peter Tompkins and Christopher Bird, presented a beguiling mashup of legitimate plant science, quack experiments, and mystical nature worship that captured the public imagination at a time when New Age thinking was seeping into the mainstream. The most memorable passages described the experiments of a former C.I.A. polygraph expert named Cleve Backster, who, in 1966, on a whim, hooked up a galvanometer to the leaf of a dracaena, a houseplant that he kept in his office. To his astonishment, Backster found that simply by imagining the dracaena being set on fire he could make it rouse the needle of the polygraph machine, registering a surge of electrical activity suggesting that the plant felt stress. “Could the plant have been reading his mind?” the authors ask. “Backster felt like running into the street and shouting to the world, ‘Plants can think!’ ”

Backster and his collaborators went on to hook up polygraph machines to dozens of plants, including lettuces, onions, oranges, and bananas. He claimed that plants reacted to the thoughts (good or ill) of humans in close proximity and, in the case of humans familiar to them, over a great distance. In one experiment designed to test plant memory, Backster found that a plant that had witnessed the murder (by stomping) of another plant could pick out the killer from a lineup of six suspects, registering a surge of electrical activity when the murderer was brought before it. Backster’s plants also displayed a strong aversion to interspecies violence. Some had a stressful response when an egg was cracked in their presence, or when live shrimp were dropped into boiling water, an experiment that Backster wrote up for the International Journal of Parapsychology, in 1968.

In the ensuing years, several legitimate plant scientists tried to reproduce the “Backster effect” without success. Much of the science in “The Secret Life of Plants” has been discredited. But the book had made its mark on the culture. Americans began talking to their plants and playing Mozart for them, and no doubt many still do. This might seem harmless enough; there will probably always be a strain of romanticism running through our thinking about plants. (Luther Burbank and George Washington Carver both reputedly talked to, and listened to, the plants they did such brilliant work with.) But in the view of many plant scientists “The Secret Life of Plants” has done lasting damage to their field. According to Daniel Chamovitz, an Israeli biologist who is the author of the recent book “What a Plant Knows,” Tompkins and Bird “stymied important research on plant behavior as scientists became wary of any studies that hinted at parallels between animal senses and plant senses.” Others contend that “The Secret Life of Plants” led to “self-censorship” among researchers seeking to explore the “possible homologies between neurobiology and phytobiology”; that is, the possibility that plants are much more intelligent and much more like us than most people think—capable of cognition, communication, information processing, computation, learning, and memory.

.....


http://www.newyorker.com/reporting/2013 ... ntPage=all
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Re: The Mental Life of Plants and Worms, Among Others

#16  Postby Teuton » Apr 08, 2014 4:03 pm

Teuton wrote:Moreover, I uphold and defend the following principle:
Nothing has a mind unless it has consciousness: nonconscient beings are nonminded beings (beings without mental properties).


That is, phenomenal zombies are mindless beings, because they are consciousnessless beings.
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Re: The Mental Life of Plants and Worms, Among Others

#17  Postby Teuton » Apr 08, 2014 4:08 pm

@Mr.Samsa:

It seems to me that "plant neurobiology" is a blatant misnomer. There may be some weak and vague physiological analogies, but these don't justify the use of that label. A better, more adequate and non-misleading label would be "plant electrobiology" or "plant electrophysiology".

"We maintain that plant neurobiology does not add to our understanding of plant physiology, plant cell biology or signaling. We begin by stating simply that there is no evidence for structures such as neurons, synapses or a brain in plants. The fact that the term ‘neuron’ is derived from a Greek word describing a ‘vegetable fiber’ is not a compelling argument to reclaim this term for plant biology. Let us consider the erroneous arguments that have been put forward to support the concept of plant ‘neurons’. …"

(Plant Neurobiology. No Brain, No Gain?)

Even those who use and defend the use of the label seem to concede that the prefix "neuro-" is not to be taken literally in the botanic context.

"Most of our statements and publications should have made clear that plant neurobiology is pursuing a framework of ideas that were introduced by outstanding representatives of the plant sciences such as Wilhelm Pfeffer, Charles Darwin, Julius von Sachs, Georg Haberlandt and Erwin Bünning. No one proposes that we literally look for a walnut-shaped little brain in the root or shoot tip or some myelinated superconducting nerve cells in plants. Neither did Haberlandt when he compared long-distance signalling in Mimosa with that in animals, nor Darwin when he considered the Venus’ flytrap as the most animal-like plant or conjectured that the root tip fulfills complex tasks like a brain."

(Response to Alpi et al.: Plant Neurobiology: The Gain is More Than the Name)
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Re: The Mental Life of Plants and Worms, Among Others

#18  Postby DavidMcC » Apr 08, 2014 4:12 pm

Teuton wrote:@Mr.Samsa:

It seems to me that "plant neurobiology" is a blatant misnomer. There may be some weak and vague physiological analogies, but these don't justify the use of that label. A better, more adequate label would be "plant electrobiology".
...

Agreed.
Perhaps the authors are trying to add a new meaning to the word, "neuron", but if they are, they should say so.
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Re: The Mental Life of Plants and Worms, Among Others

#19  Postby kennyc » Apr 08, 2014 4:13 pm

Teuton wrote:
Teuton wrote:Moreover, I uphold and defend the following principle:
Nothing has a mind unless it has consciousness: nonconscient beings are nonminded beings (beings without mental properties).


That is, phenomenal zombies are mindless beings, because they are consciousnessless beings.


Are you talking to yourself? :grin:

Are you actually claiming that mind doesn't exist unless consciousness does? And if so are you saying that all brains are consciousness? Or alternatively that some brains have no mind aspect?
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Re: The Mental Life of Plants and Worms, Among Others

#20  Postby DavidMcC » Apr 08, 2014 4:22 pm

kennyc wrote:
Teuton wrote:
Teuton wrote:Moreover, I uphold and defend the following principle:
Nothing has a mind unless it has consciousness: nonconscient beings are nonminded beings (beings without mental properties).


That is, phenomenal zombies are mindless beings, because they are consciousnessless beings.


Are you talking to yourself? Are you actually claiming that mind doesn't exist unless consciousness does? And if so are you saying that all brains are consciousness? Or alternatively that some brains have no mind aspect?

Of course, you have to define "mind" rather carefully, but I regard various simple animals with brains (eg, insects) as having brains, but probably no mind. Any decisions thay make are not the result of thought in the mammalian sense. I'm sure they do not have opinions, or bear grudges.
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