
The case against plant consciousness - Hooke
https://news.ucsc.edu/2019/07/plant-consciousness.html
======
anon_z88
While I agree with his reasoning based on his definition of consciousness, I
am not sure if this is the most appropriate way of defining consciousness.

We still do not properly understand it, thus we cannot define it. While I try
to stray from vague or ambiguous interpretations, I do think it's significant
to point that out.

Let's look at the generic definition: * consciousness - "the state of being
awake and aware of one's surroundings." * awareness - "knowledge or perception
of a situation or fact."

While a plants' consciousness may not be COMPLEX, it does not mean the absence
of conscious. There are things such as cellular intelligence which we know is
exhibited in even the smallest of prokaryotes and eukaryotes cells.

At the most abstract interpretation I think consciousness can be defined as a
closed system that contain both input and output, in which information is
gathered and alters some component of the system itself.

There was a really interesting article the other day on here about how plants
were more adaptive to radiation (specifically in Chernobyl) compared to the
regions animal counterparts.

To this definition, I think plants exercise consciousness. When we look at
life we have to analyze on both the fundamental and complex aspects.

Just my 2 cents.

~~~
hathawsh
The word "consciousness" has important connotations that are not captured by
the generic definition. As others noted, an air conditioner with a built in
thermostat can fit the generic definition of consciousness.

When I say an entity is conscious, I mean to say it not only has the ability
to react to stimuli, but it can also abstractly choose how to react. It can
rewire its own reactions, not just in a Pavlovian sense, but it can also
develop internal thought frameworks and route its reactions through the
frameworks it prefers.

The only mechanism plants have for improving the way they react to their
environment is biological evolution. You could call that mechanism a type of
consciousness, but in doing so you would have to treat the _species_ as the
conscious entity, not the individual plant; individual plants are like passing
thoughts.

Thus I don't think individual plants are conscious unless they have some way
to improve their reaction to their environment outside of biological
evolution.

~~~
xkcd-sucks
Plants engage actively with their environment, and communicate with other
plants. Usually by secreting some kind of chemical ("secondary metabolite"),
which makes sense given they don't move very fast.

Things that don't move very fast are at an advantage where energy efficiency
is important. The general trend is that low-energy things modify their
environment chemically and high-energy things modify their environment
mechanically. Compare the diversity of human-discovered secondary metabolites
from plants/fungi (low power), insects/reptiles/amphibians (medium power),
mammals/birds (high power)

[https://www.mpg.de/15791/Plants_and_environment](https://www.mpg.de/15791/Plants_and_environment)

[https://en.wikipedia.org/wiki/Plant_communication](https://en.wikipedia.org/wiki/Plant_communication)

[https://pdfs.semanticscholar.org/6b23/df2807a0fb8e77c4922377...](https://pdfs.semanticscholar.org/6b23/df2807a0fb8e77c49223777bda7730f79f4d.pdf)

~~~
hathawsh
Plant communication is certainly fascinating, but I wouldn't call it a sign of
consciousness. Isn't it just another reaction to stimuli?

I can imagine an experiment where some plants are placed in an environment
where the communication chemical they secrete interacts with a gas in the air,
slowly poisoning the plants. Would the plants adapt by changing their own
behavior, or would some later generation survive due to a mutation? If they
changed their own behavior, that might point toward a kind of individual
consciousness.

~~~
Retric
The medical definition of conciseness includes things like responding to
bright light by constructing the iris. It’s not high on the scale, but it’s
very much part of the current definition in active usage. So, in practice it’s
useful have level of consciousness and as such the minimum can be extremely
low without becoming less meaningful.

More importantly as we understand more about the brain we may eventually
understand how everything works. Any definition that would then exclude humans
as conscious becomes irrelevant.

~~~
bane
> The medical definition of conciseness includes things like responding to
> bright light by constructing the iris.

Which has an interesting parallel with many plant's ability to rotate the face
of their leaves towards the current position of the sun.

~~~
hndamien
Mimosa Pudica and the Venus Fly Trap respond even faster (in iris response
like times).

[https://www.youtube.com/watch?v=BLTcVNyOhUc](https://www.youtube.com/watch?v=BLTcVNyOhUc)

------
mikeg8
In _The Hidden Life of Trees_ , one cool fact that stuck with me in support of
tree consciousness was how trees that are under attack from certain insect
species will release pheromones to warn neighboring trees. The neighboring
trees will then rapidly increase production of tanins and other defense
chemicals to stave of the insect onslaught. pretty cool

~~~
sixplusone
How do you determine whether the tree releases pheromones to _warn_ others
-vs- it _happens_ to release pheromones and it induces a response in the
others?

i.e., the former requires intent, whereas the latter simply evolutionary
pressure (since the trees with the response would fare better, thus reproduce
more successfully).

~~~
mikeg8
Good question and a difficult one for me to answer as I am no expert here. I
believe it was the discovery that trees were using pheromones during an acute
external event, with or without "intent" as we understand it, to alter
neighboring trees, that was surprising to the researchers as we typically
associate pheromones with animals.

If a single tree under duress is using its resources and energy to signal to
_other_ trees that have no way of directly helping the tree in question, what
evolutionary advantage is being provided to the tree releasing the pheromones?

Not sure I am able to expand on this but it seems that the trees may have an
awareness of your last line: _" since the trees with the response would fare
better, thus reproduce more successfully"_, and that awareness may be a form
of consciousness different than our own.

~~~
tempguy9999
The trees were acacias (there may be other species that do this, I don't know)
and the pheromone was ethylene, which is a very simple gas that's used in
development of other things in plants, famously like fruit ripening but likely
more (can't remember, prob bud development).

<[https://asknature.org/strategy/leaves-signal-presence-of-
pre...](https://asknature.org/strategy/leaves-signal-presence-of-predators/>)

> If a single tree under duress is using its resources and energy to signal to
> other trees that have no way of directly helping the tree in question, what
> evolutionary advantage is being provided to the tree releasing the
> pheromones?

Its genetic legacy is being enhanced, if the trees it's protecting are
related, which likely they are (very elegant phrasing though! upvoted just for
that)

> thus reproduce more successfully", and that awareness may be a form of
> consciousness different than our own

Hmm. Be careful here. I need to sit down and read and understand this so
please recognise I'm dumping this on you, but

"Michie’s design, called MENACE, was a large pile of matchboxes that contained
a number of beads and learned to play tic-tac-toe."

...

"MENACE could never win against the perfect algorithm, but ended up drawing
every time after about 90 games, making it equally as perfect"

<[https://opendatascience.com/menace-donald-michie-tic-tac-
toe...](https://opendatascience.com/menace-donald-michie-tic-tac-toe-machine-
learning/>)

I dunno. Where do you draw the line? HTH anyway.

------
plutonorm
This just sounds like a member of the old guard being uncomfortable with
progress. His arguments dont seem very strong, questions over why plants would
have such a capacity. Then some hand waving about alternative explanations for
experimental results. Probably just another case of the dismantling of human
exceptionalism making people uncomfortable.

~~~
dbt00
Or perhaps exceptional claims (plants have brains we just can’t see them)
require exceptional evidence.

~~~
blancheneige
Like the exceptional claim that human consciousness resides in the brain
despite documented evidence of remote viewing [1], terminal lucidity [2],
memories of past lives [3], etc.? Maybe it's time these "scientists" start
doing actual science instead of sticking to their ultra-materialist dogma.

[1]
[https://fas.org/irp/program/collect/air1995.pdf](https://fas.org/irp/program/collect/air1995.pdf)

[2] [https://med.virginia.edu/perceptual-studies/wp-
content/uploa...](https://med.virginia.edu/perceptual-studies/wp-
content/uploads/sites/360/2017/01/NDE61_terminal-lucidity-JNMD.pdf)

[3] [https://med.virginia.edu/perceptual-
studies/publications/aca...](https://med.virginia.edu/perceptual-
studies/publications/academic-publications/children-who-remember-previous-
lives-academic-publications/)

~~~
pixelbash
Without leaning one way or the other I've always wondered what neuroimaging
one of these experiences would look like. If nothing obvious is happening and
the imagee reports a rich and detailed experience it might be persuasive.

~~~
blancheneige
Indeed. Severe cases of hydrocephalus [1], for example, where an otherwise
functional individual is missing large portions of their brain may provide
partial answers.

[1] [https://med.virginia.edu/perceptual-studies/wp-
content/uploa...](https://med.virginia.edu/perceptual-studies/wp-
content/uploads/sites/360/2017/12/Discrepancy-between-cerebral-structure-and-
cognitive-functioning-JNMD.pdf)

------
rendall
I'm sure that "consciousness" is carefully defined in the paper, but, from the
article "...whether plants can think, learn, and intentionally choose their
actions..." is a much easier position to debate than whether plants are in
some sense aware of themselves, their environment and others like themselves,
which is what I think of when I hear "consciousness".

~~~
AnIdiotOnTheNet
Honest question: it what sense can anything that exists in an environment be
said to _not_ be aware of it? How do you define "awareness" outside of
observed reactions to stimuli, which everything in the universe exhibits to
varying degrees of complexity?

I submit that what we think of as "consciousness", the awareness of being, is
impossible within a model based purely on objectively measurable criteria.

~~~
rendall
You could very well be right! The term "consciousness" is pretty loaded. Even
"awareness" is perhaps too vague and indefinable for scientific discourse.

------
lioeters
For a remarkable footage showing how plants might fit some definition of
"conscious", I recommend the French documentary called Microcosmos.

[https://www.imdb.com/title/tt0117040/](https://www.imdb.com/title/tt0117040/)

[https://en.wikipedia.org/wiki/Microcosmos_(film)](https://en.wikipedia.org/wiki/Microcosmos_\(film\))

Some of the scenes in time-lapse ("fast motion"), you can see how plants reach
out their vines and leaves, moving and feeling the world around them. So, at
least they seem to have a level of "awareness", by some definition of the
term.

Anecdotally, I've had countless experiences of what might be called
"consciousness" in all living beings - but then again, it depends what one
means by that word.

Edit: I mean, is a maze-solving slime mold conscious? And what makes human
consciousness so uniquely different from slime mold's?

~~~
tempguy9999
Is this the correct film? The links & the wiki page on it talk exclusively
about insect interaction.

> how plants reach out their vines and leaves, moving and feeling the world
> around them

I could argue cold water dropped into a very hot pan 'spreads out' to 'feel'
its environment, 'withdrawing' from the metal where it can.

~~~
lioeters
A big portion of the film is about insects - it also contains some wonderful
footage (with some high-tech macro photography) of plants and the garden where
it all takes place.

Good point about a water droplet's behavior, how it seems to be "alive" in
some aspects - all due to physical/chemical reations. I think it's related to
the question of what "alive" means, and how it's different from inert, non-
living material.

With slime mold, much of its behavior is just like water - spreading,
dripping, with surface tension, etc. - but there's definitely a difference
(perhaps only subjectively), that an observer would say it "feels its way"
toward a food source. I suppose the fact that we ascribe "feeling" to it,
means we consider it alive, aware, and perhaps conscious.

~~~
tempguy9999
> With slime mold...

Seems it goes further. "People are irrational. Example: You wouldn’t buy a new
dress, or suit, that costs $100 (‘that’s far too much to spend!’) but you
would buy one that was $300, but is now ‘reduced’ to $150 (‘but just look at
how far down it’s come!’) Sound familiar? You’re not alone, it’s fairly well-
known that humans are irrational (at least by those in advertising- some
products in supermarkets are never meant to be bought- they’re just there to
get you to buy other products more), but are other animals just as
irrational?"

Turns out slime moulds fall for it too. Full article
[https://blogs.scientificamerican.com/not-bad-
science/think-y...](https://blogs.scientificamerican.com/not-bad-
science/think-you-re-sometimes-irrational-you-re-not-the-only-one-8211-slime-
moulds-are-irrational-too) That really complicates thins.

All that said, I am really uncomfortable talking about consciousness in these
contexts at all, for obvious reasons. When we can identify and quantify, I'll
talk. See my point elsewhere about matchboxes learning.

Edit: fixed link

~~~
lioeters
Ah, I love slime moulds (I thought "mold" was American spelling, but
apparently even Scientific American spells it "mould") - thank you for the
article. It's funny to think of moulds making irrational decisions.

> slime moulds make decisions through comparison to the other available
> options, rather than having an intrinsic value for things

That sense of subjectivity and "thought" process to make decisions, sure
sounds like consciousness to me - but then again, a stream flowing down a
mountain also "makes decisions", and I'm not sure if there's a quantifiable
difference.

I just read the article you linked elsewhere: How 300 Matchboxes Learned to
Play Tic-Tac-Toe [0]. When we call a completely mechanical process "learning",
it seems to imply some kind of subjectivity and "thinking".

It's hard for me to pinpoint, what is the difference between a human and a
machine learning? The difference seems merely the level of complexity.

Discussion about consciousness usually breaks down, I think, because the root
of this concept is in our belief systems and philosophical view of life. At
one end of the spectrum, all of existence is "conscious" in varying degrees;
at the other end, nothing is really "conscious", it can all be explained as
mechanical processes. The latter used to be a "heretical" worldview, to deny
the "spirit" pervading all creation. These days, I'd say the former view is
the odd one out, being unscientific (without experimental evidence) and based
on an iffy definition of consciousness.

[https://opendatascience.com/menace-donald-michie-tic-tac-
toe...](https://opendatascience.com/menace-donald-michie-tic-tac-toe-machine-
learning/)

\---

Edit: Here's a quote I just came across:

> Freeman Dyson argued that "mind, as manifested by the capacity to make
> choices, is to some extent inherent in every electron."

..And a comment elsewhere mentioned, "consciousness as an emergent property of
physical systems". That seems to be getting closer to a reasonable
definition/explanation.

~~~
tempguy9999
Agreed about the spelling, I thought it was UK/US mold/mould.

If you like slime moulds then, just in case you haven't met Dictyostelium
discoideum, check out that on youtube. It goes from a collection of single-
cells to a 'slug', a small multi-cellular organism which goes for a wander.
Quite mind-blowing when I first met this behaviour.

All I can say is consciousness is a bugger. Everyone seems to have some idea
of what it is except me, and I'm not going to claim that I am. I just don't
know.

Anyway, a pleasant and constructive discussion, thanks!

------
yes_man
A thing being alive (collection of cells being "not dead") and sentient are
two different things. If we assume sentience is some kind of concentration of
information, then I would assume regular plants' synapses are not complex
enough to create a relevant feedback loop of consciousness. Mushrooms and
their networks (interconnected myceliums) on the other hand may be a different
case.

~~~
anon_z88
This is actually a really interesting comparison. From what I have studied,
mushrooms behave similar to a neural network. This is one of the reasons they
are so good at revitalizing forests and are seemingly unaffected by viruses.
Not to mention their benefits on immune regulation in primates.

------
CephalopodMD
This relies on the assumption that the authors model of consciousness is
"correct" for lack of a better term. If you accept this model, then we should
be able to agree on this conclusion, but it's not like this is the only model
of consciousness out there. This is just one model of one type of
consciousness that we think we can agree on. The truth is, we don't know that
plants aren't conscious, just that if they are, they don't use the same
mechanisms to experience it. It's like saying that life is impossible on a
planet without carbon. It's possible that silicon based life exists it there
somewhere, we've just never directly observed it.

------
ex3xu
For a layman's introduction to the case for plant consciousness, Monica
Gagliano and her plant consciousness experiments were featured on Radiolab
last year (transcript available): [https://www.wnycstudios.org/story/plant-
parade](https://www.wnycstudios.org/story/plant-parade)

~~~
bigiain
I saw her present at a conference recently, and subsequently bought her book.
I'm finding it all fascinating, especially the pea plant experiment. I am not
well enough informed about the state of the art in either consciousness
research/thinking or plant reactions/behaviours, but it's certainly made me
acutely aware there's something going on there which doesn't fit in with my
mental model of how plants work.

I'm going to be following along here for quite some time I suspect...

------
sova
Fungal networks act as a communication web. All plants are part fungi. The
layer of mycelium in the dirt is both a digestive tract and a lung. We carry
our stomachs, intestines, and lungs in sacks called bodies as we walk around,
fungi are laid down instead. Fascinatingly, mycelium break down rocks and
create soil from stone. Fungal networks will also allow inter-plant
communication for insect-warding chemicals to be released, and also fungi will
decomposition logs which provide bees with vital Cytochrome P450 action that
cleanses their system of virii.

------
azeotropic
I'm not sure why having neurons enters into the equation _at all_ when
deciding whether something is conscious.

This is a hard question and the Feinberg-Mallatt definition of consciousness
seems circular.

An artificial or alien life form might possess consciousness without having
traversed the same evolutionary trajectory as animals, and will probably not
possess animal neurons. Even a sufficently diverged animal might use novel
strategies for organizing neurons (or alternatives to neurons?) to sense,
move, focus attention, and remember.

~~~
crispinb
> I'm not sure why having neurons enters into the equation at all when
> deciding whether something is conscious.

Because neuroscience is bigger business than philosophy.

------
MisterOctober
Those interested in this topic may wish to check out Michael Marder's "Plant-
Thinking" [2013] -- on the philsophical rather than scientific end of the
spectrum, but thought-provoking.

------
axilmar
In my humble opinion, in a nutshell:

There is no such thing as consciousness, i.e. a mechanism that defines
consiousness.

There is only a simulation process inside organisms that tries to mimic
reality in order to predict the outcome of the current situation and
subsequently produce a 'get away'-oriented or 'stay'-oriented response.

This simulation process' complexity is relative to the complexity of the
organism.

The more complex the simulation is, the clearer the definition of objects in
it is.

The clearer the definition of objects is, the clearer the definition of self
is.

The clearer the definition of self is the higher the degree of 'consciousness'
is.

I.e. consciousness can be defined as the ability of something to perceive
itself.

With that definition, it is clear that that ability of self-perception changes
from organism to organism.

Thus plants have a low ability to perceive themselves, and humans have the
highest.

If we are searching for the mechanism of consciousness, we will never find it,
because it doesn't exist: consciousness is an emergent phenomenon that arises
from the operations of an organism.

------
aidoejebrji
>“Feinberg and Mallatt concluded that only vertebrates, arthropods, and
cephalopods possess the threshold brain structure for consciousness.

The relationship betwen brain structure and consciousness is so poorly
understood that this statement is basically idiotic. We know various ways to
affect consciousness in humans. For example, using blunt force or drugs.
However, we have no understanding at all of any mechanisms by which matter
gives rise to consciousness and we cannot even be sure that matter does give
rise to consciousness. And we have no way to evaluate the relationship between
matter and consciousness in non-human entities like plants that do not
communicate to us in any understandable (to us) way about their consciousness
or lack of it.

It often amazes me how many people are highly advanced in their own technical
fields but fail to grasp the hard problem of consciousness - something that
can be understood by a bright kid.

------
rolph
There seems to be a predisposition toward consciousness as a property of
nervous systems, or biological systems.

in speculation perhaps the concept of consciousness as an emergent property of
physical systems should be explored. if consciousness is dependent on
persistence of a quantum mechanism it is possible for consciousness to exist
as a result of any sufficiently spanning rule parsing interactions; And i'll
just leave this right here;

[https://en.wikipedia.org/wiki/Quantum_mind](https://en.wikipedia.org/wiki/Quantum_mind)

[https://www.goodreads.com/book/show/183954.Hidden_Order](https://www.goodreads.com/book/show/183954.Hidden_Order)

------
bin0
So here's an interesting question: if plants are conscious, can vegans eat
them? And if not, what will they eat? Not trying to troll vegans; if this is
different and some one can enlighten me, I'd appreciate it.

~~~
krisrm
I'm not a vegan, but if you think of veganism as more of a "harm reduction"
approach to eating, it doesn't matter whether you define plants to be
conscious or not. As in, it causes relatively more harm to a large number of
organisms to eat an animal as food (the animals are presumably going to eat
plants anyway), versus cutting out the middle man and just eating plants.

~~~
MisterOctober
Vegan here -- naturally, there are as many philosophical approaches to vegan
practice as there are vegans, but for me and others I know, it definitely is
oriented toward 'harm-reduction' [or as I like to say, minimizing
exploitation].

It's impossible to live and thrive without being detrimental to other
organisms - for me, the idea is to accept the inevitable cycle of struggle and
violence, while minimizing the _exploitative treatment_ of other beings [plant
or animal -- easier said than done with regard to plants -- one easy step is
to include as much fruit and perennial leaf matter in the diet as practical
[i.e., the plant is treated more like something to be nurtured rather than
merely 'grown and discarded']

~~~
ianai
I went vegan initially after comparing the harmful effects of animal products
with the relative ease of eating something else. Subjectively, I feel much
healthier eating plant based, Whole foods. I have noticed beneficial effects
as well-lost weight, for instance. Though I do perceive eating plants as more
moral than animal products, as well. It seems like plants don’t experience
treatment like animals do, just as a general.

------
hndamien
This discussion appears to have completely ignored the concept of a
"sensorium" for a definition of consciousness which seems to me to be the only
defining requirement. Whether or not it is possible to externally detect this
is an open question.

It is hard to imagine that anything with eyes doesn't have this, and yet
functioning eyes are clearly not a requirement. The only requirement at all
one would assume is integrated information processing - but even that is not
necessarily a given.

------
m3kw9
To build that case you need most people to agree on what consciousness means
first. So far no one still understand fully what it means

------
sebringj
I would have to think something like... Plants cannot plan, reason or
postulate or conceptualize etc, they can only respond similar to a chemical
reaction but with the added complexity of evolution giving them much more
nuanced reactions appropriate to specific scenarios... rather than trying to
say the word consciousness as that is a loaded concept.

------
crispinb
I chuckled at the notion that attributing consciousness to plants is
'anthropomorphizing'.

------
jdreyfuss
This article makes two assumptions that need more support. One, that having a
particular "threshold brain structure" is a necessary condition for
consciousness. And two, that consciousness is a binary, as opposed to a
spectrum.

------
rafaelvasco
We don't really understand what consciousness is, so no one can say that
plants have no consciousness. For me , everything has consciousness, but in
varied degrees, or frequencies in a spectrum of existence.

------
kingkawn
It’s so clear watching them, especially if you use time lapse photography,
that they are conscious.

------
nabla9
They're made out of MEAT
[https://www.youtube.com/watch?v=GggK9SjJpuQ](https://www.youtube.com/watch?v=GggK9SjJpuQ)

------
bitwize
For now. Wait till some superintelligence gives them skrodes.

------
wetpaws
Plants don't have consciousness because. They. Don't. Have. Brains.

------
hirundo
If plants have no consciousness does that make them any less worthy of care?
Consciousness is nice, I'm glad I have some, but it's just one among many
strategies that may help us replicate. Like flight or teeth or roses. An
unconscious organism is different than a conscious one but not necessarily
lesser in the way that matters: genetic survival.

It may be that consciousness is a net positive to us in that it lets us adapt
to conditions more quickly. Our genes may last longer than plant genes as a
result. But it also burdens us with destructive tendencies that threaten our
survival. The jury is out.

~~~
rotrux
> "If plants have no consciousness, does that make them any less worthy of
> care?"

No it doesn't, but that's not what's at debate. The fact anyone needed to be
told plants aren't conscious is kind of crazy.

There's an insinuation that level-of-consciousness is the measure by which we
should judge the importance of organisms. This is an anthropocentric view of
life, and a shallow one at that.

