Scientific Theory - Do Plants Feel Pain?

[DevilWithaHalo]

I wanted to get some additional perspective on this topic; do plants feel pain? I?ve recently had a very long discussion with someone about this topic and we?ve ran into some snags. Here are some of the points we were attempting to clarify to help in the discussion? (I?ll keep the prevailing discussion out of it so we don?t have any unneeded bias)

Pain is loosely defined as physical suffering/distress as due to injury or illness. The definition really got us thinking that is obvious based on that definition that plants do in fact feel pain do to the way they react to their surrounding environments and stimuli. But that also lead us to a small snag?

Does the expression of pain determine whether or not you can feel it? This opened up another side of the question; what reactions do we feel are adequate in proving the detection of the sensation? So we decided to get a little scientific with our thoughts?

A fully developed human has 2 systems with determine their reactions to stimuli; immune system and nervous system. One is purely a chemical (good enough) response while the other is a sensory response. However, only one produces what we would call a reactionary response to pain. For example, if you prick your finger you?ll recoiled and say ouch. Your body?s immune system will respond automatically and heal itself over time.

Now take a person who for all intents and purposes is a vegetable. Their nervous system ceases to function, so they cannot have a reactionary response to outside stimuli, even though their immune system will still heal itself. (Or vice versa in some cases). So then would this mean a nervous system is required to feel pain?

Although this seems a fairly loaded question giving that things lacking of nervous systems still have a chemical reaction to damage. ?Feeling? pain becomes more important than the fact we did ?harm? the organism directly anyway. So doing the damage is OK so long as it isn?t ?hurt? by it? Seems strange. But regardless, the reactionary process is similar in both respective; survival?

Call it a survival instinct, call it a basic chemical reaction, but life forms in general are ?designed? or ?evolved? (whichever you prefer) to survive or procreate their specie. Is this not the same thing as avoiding damages suffered? What would prevent an animal with no central nervous system from simply walking into fire if they were unaware that it was damaging to them? Certainly there must be another system in place right?

Let?s talk plants. They have no nervous system, yet they seem to react to stimuli through other methods; http://www.zeenews.com/news641166.html (interesting tidbit on reactions to light, memory and resistance to disease). So they have certain chemical reactions in ways which mimic other life forms in their need for survival and resistance to pain (as defined as physical suffering due to injury or illness).

We also came up with 2 plausible additional experiments to test plant reactions to things deemed ?harmful? to all life. The first was to put a crawling plant (one that grows upward toward light the shortest distance possible) next to two equally spaced and sized grates. One would be super heated to the point of burning anything it touches, the other left at room temperature. We surmised that the plant would choose the less lethal path when growing. The 2nd experiment was to put 2 plants in 2 separate sound proof rooms. The first would receive 30 decibels (whispering) of music while the other would receive 115 decibels (rock concert). We surmised that the 115 decibel plant would wither and die sooner than the 30 decibel plant (as studies have already indicated various sounds affect plants). It became obvious with every experiment (that didn?t involve killing the plant strait away), that plants reacted in the same way other life forms do to damages.

So then we went back to ?feeling? pain. Since ?feel? is defined as a perception or sensation to something, the chemical reaction seemed to suffice in saying; ?since plants chemically react to damaging stimuli through some sensory methods (even if not quite fully understood), then plants must feel pain?. Am I personally convinced? Not entirely, although scientifically speaking, the statement has merits.

But that?s the idea behind the thread; I?d like to get some further insight into this idea. It?s always a good idea to get a fresh perspective and see areas of the topic we may have overlooked. And while I don?t think you need a PHD to join in, I would like it to remain as scientific as you are able.

 

[Judgement101]

Why are they spending money to research plant pain?

 

[mb16]

No. as as far as im aware plants dont have a:
1: brain to process pain
2: nerves to sense pain

 

[Miles000]

Why are they spending money to research plant pain?

To troll vegans.

Wouldn't surprise me.

I've often wondered that. I know they will adapt to existing 'painful' conditions. But it is never an instantaneous reaction.

 

[Judgement101]

Why are they spending money to research plant pain?

To troll vegans.

.....BRILLIANT!
(Sadly enough this is probably true)

 

[PurplePlatypus]

Well they do not have a nervous system nor, as far as we know, something that might perceive the pain. If they can do something that might be describes as feel it will be nothing like we experience and to call it pain, or the same words for what we experience, would probably be horribly inaccurate.

 

[HontooNoNeko]

No. as as far as im aware plants dont have a:
1: brain to process pain
2: nerves to sense pain

They also have no reason to feel pain. For animals it makes sense to adjust our behaviors to avoid harmful stimulus. However a plant can't move so a plant evolving pain receptors is just going to make it less likely to survive do to needing to waste extra energy on a completely useless biological trait.

So nope they don't and I highly doubt there will be any plants that feel pain around any time soon.

 

[Uskis]

"Pain" is an abstract social construct relating to human experience and human perception. It makes no sense to try to quantify it and analyze it in a natural-science discourse.

 

[Riobux]

If they do feel what could be considered a plant alternative to pain, it's probably completely different to how animals feel pain in possibly every single way.

 

[Heathrow]

I don't think high decibel noises are lethal to plants.

I wonder if we aren't confusing "aware of stimulation" with "feeling pain". Pain as it is known to most Animalia is simply a method of processing a certain set of stimuli. It is difficult to say exactly how plants process their environment since we exist in a fundamentally different way to them.

It may be the case that they have something which we would consider pain but we can not determine this from outside observation. The pain/retraction reflex which enables a person to remove their hand from a scalding surface will function exactly the same way as any other method of sensing harm in order to avoid peril. Thus a plant's ability to seek safety can be accounted for without assuming any specific "pain" process.

Edit:

It seems easy, at first, to assume that because plants lack a nervous system, neurons, electrical impulses and other necessities of Animal consciousness that plants will therefore be unable to feel pain. Consider, for a moment, the purpose of your nervous system: to transmit data from one part of a collective whole to another.

This biological necessity is not dependent on synapse and spine, rather the reverse. Your construction is based on the simple chemical bits stored in your individual cells, and it is the kludged solution of every problem that ever faced cellular life that dictates our body's architecture.

Plants share with us the ability to store and transfer data about their constituent selves. Is it a stretch to assume they are capable of finding a solution to the problem of survival which includes something very much like pain? In this, as with all matters concerning consciousness, there are no fast and easy answers, the only proper answer is, "I don't know".

 

[Tulks]

Why are they spending money to research plant pain?

To troll vegans.

Need there be any other reason?

OT: Not sure how this bears on your question, but I recall reading an article about a Japanese scientist who was increasing the antioxidant levels in potatoes by torturing them.

Source [http://www.telegraph.co.uk/health/healthnews/7959379/Zapping-spuds-with-electricity-makes-them-healthier-scientists-claim.html]

 

[chowderface]

I read a short story about this once. An inventor made a device to try and hear...something, I forget what, but what he actually ended up being able to hear was the sounds plants made when they were damaged. Flowers screaming when they were cut, grass shrieking as it was crushed underfoot, trees groaning when they were hit with an axe.

Being an empathetic fellow, he went quite mad from the stress. He actually tried to get a doctor friend to stitch up the wound created when he demonstrated the tree + axe bit.

 

[Semudara]

"Pain" is an abstract social construct relating to human experience and human perception. It makes no sense to try to quantify it and analyze it in a natural-science discourse.

I disagree with this. It can pretty much be proven that many other animal species feel pain as we do. However, I also agree with many of the other posters that while plants can be harmed and do respond to the harm, "pain" is essentially a nerve impulse with the intention of changing our behavior based on the damage, which plants don't have and have no reason to.

 

[Frizzle]

I'm not *completely sure* about them feeling pain, but I do know that some have the ability to react to stimuli such as having parts of them eaten. I read somewhere (and it'll take me a while to remember where, but I'll look) that a certain tree was able to communicate to others of it's species nearby when it was having it's leaves or flowers eaten. The other surrounding trees would make their taste turn bitter so as to deter the animal (i think it was a giraffe) from eating more.

I'd like to think that all living things have some sort of "awareness" about them that lets them know when something bad is happening. Individuals may not process it the same, but it's likely that there is a reaction to that something bad, whether we can detect it or not.

Edit: spoilered cuz it's a copy paste, but this is along the lines of what i was refering too.

Spoiler

Detection of Insect Herbivores

Mechanical damage caused by insects is not generally considered ?true? plant disease although plants have developed surveillance systems designed to recognize insect pests and respond with specific defense mechanisms. Plants can distinguish between general wounding and insect feeding by the presence of elicitors contained in the saliva of chewing insects. In response, plants may release volatile organic compounds (VOCs), including monoterpenoids, sesquiterpenoids, and homoterpenoids. These chemicals may repel harmful insects or attract beneficial predators that prey on the destructive pests. For example, wheat seedlings infested with aphids may produce VOCs that repel other aphids. Lima beans and apple trees emit chemicals that attract predatory mites when damaged by spider mites, and cotton plants produce volatiles that attract predatory wasps when damaged by moth larvae. Feeding on one part of the plant can induce systemic production of these chemicals in undamaged plant tissues, and once released, these chemicals can act as signals to neighboring plants to begin producing similar compounds. Production of these chemicals exacts a high metabolic cost on the host plant, so many of these compounds are not produced in large quantities until after insects have begun to feed.

Captcha: ainnial eatimin

 

[similar.squirrel]

Pain is, at least to some extent, a biochemical phenomenon. So it could be that news of a disaster is conveyed throughout the plant by means of hormones. But I think that would apply more to persistent environmental stimuli, as opposed to something sudden like a deer eating some of your foliage.
Tissue damage in a plant is obviously 'acknowledged' to a certain degree, because the regenerative properties of plants have been established beyond any doubt. But the idea of an entire plant responding to harmful stimuli in the manner of a 'higher' organism doesn't make much sense. My hunch is that the cells in the damaged tissue undergo differentiation following any sort of trauma, but that this is a strictly localized and the rest of the organism doesn't really 'know' much about it [damn you, telelogy]. Plant cells are a lot less specialised than animal cells, and therefore more autonomous. There isn't much need for leaf A to know that leaf H just got eaten. Well, there is, but it's not going to grow spines because that would be all Lamarckian and stuff...

I'm not great at plant physiology, though, so feel free to enlighten me.

 

[Raven's Nest]

"Pain" is an abstract social construct relating to human experience and human perception. It makes no sense to try to quantify it and analyze it in a natural-science discourse.

What? The concept of pain isn't exclusive to humans... Ever accidentally trod on a dogs paw? They yelp and might limp afterwards... Definitely a reaction to pain. My ex's mum accidentally burnt her dog with a cigarette once, obviously this hurt the dog and it's been afraid of cigarettes ever since...

OT: last I heard (and I study animal welfare), scientists aren't even sure if fish truly feel pain. I think there's a long way to go if you wanna prove that plants can, with their lack of brain and nervous system and all...

 

[DoctorPhil]

No brain, no pain.

 

[Hiikuro]

I've learned a lot about plants after having nurtured two for the past month or so. I've seen them react to stimuli and appear far more alive than I ever thought plants were. Weird thing is that I actually care for them to a similar level as to many animals I've interacted with. I am glad they were able to change my view of plants.

But that aside, I expect that the most common definition of pain requires a nervous system, and as such plants can not feel pain.

But if I may take the liberty of defining pain myself, I'd say that it is the reaction that any living being has when something harms its intent for life. Intent for life I define as the desire that all life has to stay alive (and reproduce and all that). By this plants do feel pain, as they have an intent for life that other organisms may harm.

But I only redefined the word, I didn't change reality. The easiest conclusion is though, that the processes that happen in plants when they are harmed, are different from the processes that happen in humans. For a particular definition of what I mean by 'processes'. Or: Plants may feel pain, but they feel pain in a different way to how humans do.

I really can't find any conclusive thoughts on this, as all words involved are too vague and imprecise for me to comfortably explore.

 

[Jangler]

Just because a construct responds to a damaging external stimulus doesn't mean it "feels" something in order to act that way. The function of pain in organisms with a central nervous system is to provide them with a conscious, analytical reason to avoid a behavior in a future. Humans have REFLEXES to automatically draw their hands away from, say, a hot stove. They experience PAIN to discourage this behavior in the future -- because you consciously disliked the experience of feeling pain, you'll likely be more cautious around potentially hot objects in the future.

Because plants don't consciously think or make decisions there is no reason for them to experience pain (nor do they have any biological equipment that would even ENABLE them to feel it). What causes plants to avoid harm and to grow in more suitable directions is governed by something more like human reflexes (called tropisms).

http://en.wikipedia.org/wiki/Tropism