Can plants 'see' or sense

blindfaith · #1 by **blindfaith** » Jul 08, 2011 8:28 am

i was watching a bit of attenborough last night and he was showing a species of butterfly that lays little round yellow eggs. i forget the species of butterfly and plant.
one plant that it tried to lay its eggs on, produces little yellow dots on its leaves that look a little like the eggs the butterfly lays. another plant of the same species actually produces little nodules which are round and yellow and look just like the butterfly eggs.

my question is how does the plants know what the eggs of the butterfly look like, as they dont have eyes, or any sensory organs that im aware of?
how did they evolve this trick?

sorry if its a dumb question, im not a scientific type, just curious to learn, as i never stop being amazed by nature.

thanks

Animavore · #2 by **Animavore** » Jul 08, 2011 8:32 am

It's more likely a simple chemical reaction which co-evolved with the butterfly. Plants have no nervous system and no brain to process the info so no sense.

chairman bill · #3 by **chairman bill** » Jul 08, 2011 8:37 am

Simple genetic mutation might leave some plants with yellow dots or lumps. Those plants will suffer less damage from caterpillars of those particular butterflies, produce more seeds, resulting in more of those plants with the mutation. Evolution, pure & simple. A gentic mutation resulting in purple spots would give no survival advantage & so wouldn't be selected for. It's not purposeful as you seem to imply.

Spearthrower · #4 by **Spearthrower** » Jul 08, 2011 8:53 am

Mimicry doesn't require cognition or sight - think of the peppered moth and industrial melanism. If a mutation arises that provides a benefit, it can spread throughout a population. The plant neither needs to see or know that this is to its benefit, it just is, and consequently lends it a reproductive advantage. We are seeing the product of thousands of generations of tweaking that; if we could go back to the first iteration of its arrival, it would probably only look very obliquely like a yellow egg and only provide a fraction of the payout it does today.

Mr.Samsa · #5 by **Mr.Samsa** » Jul 08, 2011 9:07 am

Whilst other people have answered your question quite well (i.e. plants don't "know" to grow yellow egg-like nodules, in the same way organisms don't "know" that they need to grow eyes), but the topic of plant intelligence is an interesting one. I recommend reading this paper: "Aspects of Plant Intelligence".

Intelligence is not a term commonly used when plants are discussed. However, I believe that this is an omission based not on a true assessment of the ability of plants to compute complex aspects of their environment, but solely a reflection of a sessile lifestyle. This article, which is admittedly controversial, attempts to raise many issues that surround this area. To commence use of the term intelligence with regard to plant behaviour will lead to a better understanding of the complexity of plant signal transduction and the discrimination and sensitivity with which plants construct images of their environment, and raises critical questions concerning how plants compute responses at the whole‐plant level. Approaches to investigating learning and memory in plants will also be considered.

It's speculative in parts, but it's an interesting read (and personally I find some arguments within it rather compelling).

ughaibu · #6 by **ughaibu** » Jul 08, 2011 9:15 am

Mr.Samsa wrote:. . . . the topic of plant intelligence is an interesting one. I recommend reading this paper: "Aspects of Plant Intelligence".

Here's another article that might be of interest: http://philosophy.eldoc.ub.rug.nl/root/ ... ninplants/

Mr.Samsa · #7 by **Mr.Samsa** » Jul 08, 2011 9:19 am

ughaibu wrote:
Mr.Samsa wrote:. . . . the topic of plant intelligence is an interesting one. I recommend reading this paper: "Aspects of Plant Intelligence".
Here's another article that might be of interest: http://philosophy.eldoc.ub.rug.nl/root/ ... ninplants/

Thanks, I haven't read that paper.

Spearthrower · #8 by **Spearthrower** » Jul 08, 2011 9:28 am

Thanks both of you - I haven't read either of those.

While I have an open-mind on the topic, and I think I am probably always one of the first to point out that we tend to use ourselves as a yardstick in definitions, I have always found this definition of 'intelligence' to be problematic:

Adaptively variable behaviour within the lifetime of the individual

That seems to be missing an element I would struggle to pin down. I would leap to say 'conscious adaptively variable... etc', but then would immediately pull back as I'd be worried that I am simply entraining my thoughts along the ultimate pathway to the human yardstick fallacy.

If species X uniformly eats a particular food source, and that source disappears for some reason and species X consequently starts eating something outside of its usual behaviorally programmed food source, would that infer intelligence? Or would it just be the appearance of intelligence?

That does not feel like a very good example, but I haven't eaten yet today and it's 4pm - so the point about food sprang to my nutrient starved brain. Probably best if I go and adapt my behaviour accordingly and get some tucker!

I'll try again later!

Mr.Samsa · #9 by **Mr.Samsa** » Jul 08, 2011 9:58 am

Spearthrower wrote:Thanks both of you - I haven't read either of those.

While I have an open-mind on the topic, and I think I am probably always one of the first to point out that we tend to use ourselves as a yardstick in definitions, I have always found this definition of 'intelligence' to be problematic:

Adaptively variable behaviour within the lifetime of the individual

That seems to be missing an element I would struggle to pin down.

I think it's important to point out that they're discussing a broad idea of 'intelligence' here, one which is essentially synonymous with "the ability to learn". As such, it's a pretty good definition, but I can understand it appearing to be lacking if we look at it from a more common understanding of 'intelligence' (which tends to refer to a higher form of cognitive functions).

Spearthrower wrote:I would leap to say 'conscious adaptively variable... etc', but then would immediately pull back as I'd be worried that I am simply entraining my thoughts along the ultimate pathway to the human yardstick fallacy.

Well I guess it comes down to how we define "conscious" here. At its core, 'conscious' simply means to be aware of your surroundings, and to possess the ability to experience. If we accept this, then it must necessarily be true that one is conscious when exhibiting that form of 'intelligence', since it's impossible to adaptively adjust to the environment without being aware of the consequences of your actions.

Spearthrower wrote:If species X uniformly eats a particular food source, and that source disappears for some reason and species X consequently starts eating something outside of its usual behaviorally programmed food source, would that infer intelligence? Or would it just be the appearance of intelligence?

What would the difference be between intelligence and the 'appearance' of intelligence? I found that Gilbert Ryle's discussion of category mistakes changed how I view issues like that of intelligence.

Spearthrower wrote:That does not feel like a very good example, but I haven't eaten yet today and it's 4pm - so the point about food sprang to my nutrient starved brain. Probably best if I go and adapt my behaviour accordingly and get some tucker! I'll try again later!

That sounds like an intelligent act! :grin:

Spearthrower · **#10** by **Spearthrower** » Jul 08, 2011 10:14 am

Mr.Samsa wrote:
I think it's important to point out that they're discussing a broad idea of 'intelligence' here, one which is essentially synonymous with "the ability to learn". As such, it's a pretty good definition, but I can understand it appearing to be lacking if we look at it from a more common understanding of 'intelligence' (which tends to refer to a higher form of cognitive functions).

I very much appreciate that - I was trying to deal with that in my opening statement.

Mr.Samsa wrote:Well I guess it comes down to how we define "conscious" here. At its core, 'conscious' simply means to be aware of your surroundings, and to possess the ability to experience. If we accept this, then it must necessarily be true that one is conscious when exhibiting that form of 'intelligence', since it's impossible to adaptively adjust to the environment without being aware of the consequences of your actions.

I was thinking more to do with the how information received from the outside world is processed. If an automatic act, such as a chemical response, occurs as a result of an environmental stimuli, it might satisfy 'adaptively variable behaviour within the lifetime of a species' but might be as 'intelligent' as a rock falling when dropped, as in, it's not processing that information, just being manipulated by it.

Mr.Samsa wrote:
What would the difference be between intelligence and the 'appearance' of intelligence? I found that Gilbert Ryle's discussion of category mistakes changed how I view issues like that of intelligence.

It's a very good article. However, if you see my above, I think I have begun to treat this. Is the organism actually doing something with the information that produces the apparently intelligent behaviour or is the behaviour a necessary result of chemical or physical forces that the organism has no other way but to obey. The latter would be problematic to include in a definition of 'intelligence', but could provide an illusion of intelligence.

chairman bill · **#11** by **chairman bill** » Jul 08, 2011 10:20 am

I've mentioned elsewhere on RatSkep that when most people talk about consciousness, they haven't got a clue what they're talking about, and if you mention plant consciousness, they think you're joking. But consciousness is a 'many varied thing', and plants do exhibit signs of a level of awareness that we can define as consciousness. Consciousness implies a certain level of 'intelligence'.

I sometimes think that in our attemtps to avoid anthropomorphism, we ignore the common heritage of life on earth, our place in the natural world, the fact of our being animals, and arrogantly assume that those qualities we recognise in ourselves are functions of being human, rather than functions of being alive, or being an animal, or a mammal, or primate, and so on.

Mr.Samsa · **#12** by **Mr.Samsa** » Jul 08, 2011 10:29 am

Spearthrower wrote:
Mr.Samsa wrote:Well I guess it comes down to how we define "conscious" here. At its core, 'conscious' simply means to be aware of your surroundings, and to possess the ability to experience. If we accept this, then it must necessarily be true that one is conscious when exhibiting that form of 'intelligence', since it's impossible to adaptively adjust to the environment without being aware of the consequences of your actions.

I was thinking more to do with the how information received from the outside world is processed. If an automatic act, such as a chemical response, occurs as a result of an environmental stimuli, it might satisfy 'adaptively variable behaviour within the lifetime of a species' but might be as 'intelligent' as a rock falling when dropped, as in, it's not processing that information, just being manipulated by it.

Mr.Samsa wrote:
What would the difference be between intelligence and the 'appearance' of intelligence? I found that Gilbert Ryle's discussion of category mistakes changed how I view issues like that of intelligence.

It's a very good article. However, if you see my above, I think I have begun to treat this. Is the organism actually doing something with the information that produces the apparently intelligent behaviour or is the behaviour a necessary result of chemical or physical forces that the organism has no other way but to obey. The latter would be problematic to include in a definition of 'intelligence', but could provide an illusion of intelligence.

Well I think the problem with this is that there is fundamentally no difference between behavior which is a result of chemical or physical forces, and behavior where the organism has a 'free' choice. I think the distinction there would be between classical and operant conditioning, but even when (for example) a chimp is intelligently solving some complex problem, it is still forced to obey the basic laws of behavior when it does so.

I understand that classical conditioning might be too simple for us to consider what is 'intelligent', but a lot of the behaviors described by Trewavas are more complex than classical conditioning (or simple chemical reactions). For example, I think he explains how some plants learn to predict insect attacks, and to engage in behaviors that avoid being attacked again in the future. This goes beyond what can be explained by simple chemical responses - the question then is whether it qualifies as "intelligence".

(Sorry, all that was poorly explained. I'll try again tomorrow if it didn't make sense :grin:

).

Spearthrower · **#13** by **Spearthrower** » Jul 08, 2011 10:31 am

I'm going to put up this as an example of what I was talking about:

http://www.sciencedaily.com/releases/20 ... 125531.htm

Oil Droplets Can Navigate Complex Maze

ScienceDaily (Feb. 28, 2010) — Call them oil droplets with a brain or even "chemo-rats." Scientists in Illinois have developed a way to make simple oil droplets "smart" enough to navigate through a complex maze almost like a trained lab rat.

Obviously the language in the article is meant to be provocative, but would we agree that there is no intelligence operating here on the part of the oil?

Spearthrower · **#14** by **Spearthrower** » Jul 08, 2011 10:37 am

Mr.Samsa wrote:
Well I think the problem with this is that there is fundamentally no difference between behavior which is a result of chemical or physical forces, and behavior where the organism has a 'free' choice.

That's precisely where I have a 'problem'. I am open to accepting that the problem is one of my own thought processes limitations than necessarily being a factor in this question, but I have to return to the falling rock. If anything, it seems to me that it is somewhere here where the division between intelligence and the appearance of intelligence lies. I was cautious not to use the word choice, as that adds another layer. I am more focused on whether the information is being processed in some way rather than something causing an effect.

ramseyoptom · **#15** by **ramseyoptom** » Jul 08, 2011 7:59 pm

Let's start at a basic level, plants can sense light direction, just grow some seedlings on a window sill and watch then grow towards the light. Again plants seeds and you can see the roots grow downwards and the stem growing upwards, so if the seed is well under the soil then it must be using gravity to orientate itself.

I think it has been shown that the english oak does when infested by parasites release a chemical warning signal to other oaks in the woodland and the other oaks then respond by increasing production of tannins etc in the leaves to make them more bitter.(I am not sure of the references, but then I am no botanist). I also think that it has been shown that plants can engage in a form of chemical warfare against each other.

There is probably a lot more to be discovered about plants, but I suspect soem this area of research is just 'not sexy'!

I suspect that David Attenborough's "The Private Life of Plants" is the source of my memories.

Peter Brown · **#16** by **Peter Brown** » Jul 08, 2011 9:04 pm

I watched some old research performed years ago on the BBC. Simple test really, they hooked some plants to some sensor and cut the lawn, when the lawnmower man entered the room the plants screamed.

Spearthrower · **#17** by **Spearthrower** » Jul 09, 2011 3:25 am

I don't really get that Peter.... was the test showing that the plants were reacting to a chemical on the man? When it said 'scream', clearly that was an interpretation of some kind of signal - what signal and how did they measure it?

Mr.Samsa · **#18** by **Mr.Samsa** » Jul 10, 2011 7:20 am

Spearthrower wrote:I'm going to put up this as an example of what I was talking about:

http://www.sciencedaily.com/releases/20 ... 125531.htm

Oil Droplets Can Navigate Complex Maze

ScienceDaily (Feb. 28, 2010) — Call them oil droplets with a brain or even "chemo-rats." Scientists in Illinois have developed a way to make simple oil droplets "smart" enough to navigate through a complex maze almost like a trained lab rat.

Obviously the language in the article is meant to be provocative, but would we agree that there is no intelligence operating here on the part of the oil?

Yes, there is no intelligence here as there is no learning taking place. The oil droplet does not learn the correct response by interacting with its environment and assessing the consequences of particular actions, so I don't think it could be considered an instance of intelligence (but, like you say, the language used is not intended to be taken so literally).

Spearthrower wrote:
Mr.Samsa wrote:
Well I think the problem with this is that there is fundamentally no difference between behavior which is a result of chemical or physical forces, and behavior where the organism has a 'free' choice.

That's precisely where I have a 'problem'. I am open to accepting that the problem is one of my own thought processes limitations than necessarily being a factor in this question, but I have to return to the falling rock. If anything, it seems to me that it is somewhere here where the division between intelligence and the appearance of intelligence lies. I was cautious not to use the word choice, as that adds another layer. I am more focused on whether the information is being processed in some way rather than something causing an effect.

I think the problem is that "information processing" IS "something causing an effect". The only difference is that the cause of the action is not necessarily immediately present or directly observable. When a rat learns how to navigate a maze (i.e. demonstrates some level of intelligence), all we are talking about is essentially "falling rocks" in the brain. I think the important part is the interaction between the organism/agent and the environment.

In other words, when a cold wind blows over our skin and we get goosebumps, there is no intelligence here. However, if we conditioned someone to get goosebumps whenever we ring a bell, then this is an example of learning (and, arguably, intelligence in some form). If the organism were then to learn to avoid being in situations where the bell is, or learns to escape the wind that the bells signals, then that would surely be an example of intelligence. The fundamental processes controlling the conditioned goosebumps, and the escape/avoidance of the wind/bell, are exactly the same.

So if by "appearance of intelligence" you mean something similar to the initial goosebumps response, then I agree that it shouldn't be considered an instance of intelligence.

Spearthrower wrote:I don't really get that Peter.... was the test showing that the plants were reacting to a chemical on the man? When it said 'scream', clearly that was an interpretation of some kind of signal - what signal and how did they measure it?

The plant "scream" is a release of ethylene gas, and they release it whenever they're under stress. Scientists built a machine that excited the ethylene molecules, which released a tiny shock wave of energy. Then they amplified this shock wave and set up a highly sensitive microphone to get the "scream". I can't find any good articles on it that explain it well though.

I think the 'lawnmower man' example, however, is probably a bit of pseudoscience - something alone the lines of plant perception, where they hook the plants up to an EEG machine or a galvanometer. Whilst plants learning to respond to a potential threat is plausible (in my opinion), I'd have to read more about how they would learn to identify the lawnmower man. Especially if we're talking about grass, since there would presumably be no method by which learning could take place as grass (as far as I know) has no real defence mechanism - meaning that identifying the lawnmower man would be redundant and no learning would occur.

Spearthrower · **#19** by **Spearthrower** » Jul 11, 2011 10:56 am

Mr.Samsa wrote:
Spearthrower wrote:I'm going to put up this as an example of what I was talking about:

http://www.sciencedaily.com/releases/20 ... 125531.htm

Oil Droplets Can Navigate Complex Maze

ScienceDaily (Feb. 28, 2010) — Call them oil droplets with a brain or even "chemo-rats." Scientists in Illinois have developed a way to make simple oil droplets "smart" enough to navigate through a complex maze almost like a trained lab rat.

Obviously the language in the article is meant to be provocative, but would we agree that there is no intelligence operating here on the part of the oil?

Yes, there is no intelligence here as there is no learning taking place. The oil droplet does not learn the correct response by interacting with its environment and assessing the consequences of particular actions, so I don't think it could be considered an instance of intelligence (but, like you say, the language used is not intended to be taken so literally).

And so my obvious follow up is 'do plants?' Or are they like the oil? Or are they on a gradient somewhere between?

Mr.Samsa wrote:
Spearthrower wrote:
Mr.Samsa wrote:
Well I think the problem with this is that there is fundamentally no difference between behavior which is a result of chemical or physical forces, and behavior where the organism has a 'free' choice.

That's precisely where I have a 'problem'. I am open to accepting that the problem is one of my own thought processes limitations than necessarily being a factor in this question, but I have to return to the falling rock. If anything, it seems to me that it is somewhere here where the division between intelligence and the appearance of intelligence lies. I was cautious not to use the word choice, as that adds another layer. I am more focused on whether the information is being processed in some way rather than something causing an effect.

I think the problem is that "information processing" IS "something causing an effect". The only difference is that the cause of the action is not necessarily immediately present or directly observable. When a rat learns how to navigate a maze (i.e. demonstrates some level of intelligence), all we are talking about is essentially "falling rocks" in the brain. I think the important part is the interaction between the organism/agent and the environment.

In other words, when a cold wind blows over our skin and we get goosebumps, there is no intelligence here. However, if we conditioned someone to get goosebumps whenever we ring a bell, then this is an example of learning (and, arguably, intelligence in some form). If the organism were then to learn to avoid being in situations where the bell is, or learns to escape the wind that the bells signals, then that would surely be an example of intelligence. The fundamental processes controlling the conditioned goosebumps, and the escape/avoidance of the wind/bell, are exactly the same.

So if by "appearance of intelligence" you mean something similar to the initial goosebumps response, then I agree that it shouldn't be considered an instance of intelligence.

Yes, that's another analogy for what I am trying to express here.

Mr.Samsa wrote:
Spearthrower wrote:I don't really get that Peter.... was the test showing that the plants were reacting to a chemical on the man? When it said 'scream', clearly that was an interpretation of some kind of signal - what signal and how did they measure it?

The plant "scream" is a release of ethylene gas, and they release it whenever they're under stress. Scientists built a machine that excited the ethylene molecules, which released a tiny shock wave of energy. Then they amplified this shock wave and set up a highly sensitive microphone to get the "scream". I can't find any good articles on it that explain it well though.

Aye, I've heard of that, but Peter's example seemed a serious step away from that.

Mr.Samsa wrote:I think the 'lawnmower man' example, however, is probably a bit of pseudoscience - something alone the lines of plant perception, where they hook the plants up to an EEG machine or a galvanometer. Whilst plants learning to respond to a potential threat is plausible (in my opinion), I'd have to read more about how they would learn to identify the lawnmower man. Especially if we're talking about grass, since there would presumably be no method by which learning could take place as grass (as far as I know) has no real defence mechanism - meaning that identifying the lawnmower man would be redundant and no learning would occur.

As a corollary to your goosebumps and learning.... when an organism gets a virus, it builds up antibodies. Consequently is has 'learned' from its environment, and will be able to apply that learning in the future. However, would that be considered intelligent, or would it be like the former instance of goosebumps?

Mr.Samsa · **#20** by **Mr.Samsa** » Jul 13, 2011 6:00 am

Spearthrower wrote:And so my obvious follow up is 'do plants?' Or are they like the oil? Or are they on a gradient somewhere between?

There are difficulties in answering this, mostly the fact that plants move on a vastly different time scale compared to animals. But Trewavas makes arguments which suggest that plant behavior is more similar to animals than to oil.

Spearthrower wrote:As a corollary to your goosebumps and learning.... when an organism gets a virus, it builds up antibodies. Consequently is has 'learned' from its environment, and will be able to apply that learning in the future. However, would that be considered intelligent, or would it be like the former instance of goosebumps?

Has it "learned" from its environment? I don't think it's an example of 'adaptively variable behavior' (learning) because it's adaptive, but not variable. So it's the same sort of response as goosebumps in the wind (i.e. an "unconditional response"). Interestingly, our immune system can be conditioned, so by associating an increased or decreased immune response with something like the ringing of a bell, we can systematically increase or decrease the immune response by ringing a bell. This would be an example of learning, but it would be debatable whether it would be "intelligence". It's certainly a kind of intelligence, but it would probably be an example of "biological intelligence", rather than "behavioral intelligence". Intelligence, in this example, would be if an organism learnt to avoid a room with lots of bells in it, or it executed some escape response when presented with a bell.