# Do tarantulas have brains?



## Alicemolted (Nov 6, 2007)

and if they do.. are they called something else? and if they dont.. how on earth do they function?
x


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## butch4skin (Nov 6, 2007)

They have "coalesced ganglii" or something. Basically a crappy excuse for a brain, though I'd never say that in front of any of mine.

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## Stylopidae (Nov 6, 2007)

There is a lot of information about how the nervous systems of invertebrates is set up here.

http://homepage.ntlworld.com/spydawebb/anatomy.html

They do have a brain and a nervous system with a higher degree of centralization than most invertebrates, but their nervous system most likely works in a similar fashion.

Their nervous systems are nowhere near as complex as ours are...they don't sleep, they don't feel pain, don't feel blue, etc.

They recieve information and react to it. There is very little information processing capability in their nervous system.

http://www.earthlife.net/chelicerata/s-anatomy.html

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## Merfolk (Nov 6, 2007)

You can't claim for a total absence of intelligence, but it's limited.

They can recall spacial disposition of things and such...


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## Vietnamese510 (Nov 6, 2007)

*wow*

i never knew that Ts dont sleep


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## Stylopidae (Nov 6, 2007)

Merfolk said:


> You can't claim for a total absence of intelligence, but it's limited.
> 
> They can recall spacial disposition of things and such...


They can also learn behaviors...one person reported his tarantulas learned to tap their waterdishes on the side of their enclosures.

Their cognative abilities are _very_ limited. I don't like to use the word intelligence because the second I use that word, people start comparing them to cats, dogs and higher animals with much, much more complex nervous systems and start attributing abilities to tarantulas that are impossible for the tarantula to posess given the layout of it's nervous system.

Of course...when you ask a question like this, you're really asking two questions (whether or not you like/realize it).

First question...how is the term brain/intelligence defined?

Second question...does the animal/organ/behavior meet this definition?

The answer to the second question is dependant on the first and by manipulating the answer to the first question, you can come up with any answer to the second question you'd like.

The relevant definition of intelligence from Dictionary.com:



> capacity for learning, reasoning, understanding, and similar forms of mental activity; aptitude in grasping truths, relationships, facts, meanings, etc.


Well, under this definition tarantulas and similar inverts posess no intelligence because this definition was formulated to compare and contrast the cognative abilities of different _people_ and higher animals.

A tarantula can not understand, reason, grasp truths, understand most types of relationships (again...another definition I could fiddle with), facts nor meanings.

However, they can certianly learn to a certian degree.

So I prefer to stay away from loose terms like 'intelligence' and instead explain the nervous system and it's capabilities in a very long, drawn out explanation because short explanations often leave people with the wrong impressions.

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## UrbanJungles (Nov 6, 2007)

Touch alone can determine whether or not something is a danger usually by smell.  For example, if a T touches (smells) something unfamiliar it may be very cautious until it can determine the new thing is not a threat. If the "thing" keeps coming after them then there's no doubt it's a threat and a fight or flight response is initiated.


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## Code Monkey (Nov 6, 2007)

butch4skin said:


> Or better yet, how do we know that an animal _can_ interpret stimuli through touch as dangerous, yet most likely cannot feel physical pain.


Easy, pain is a psychological phenomenon linked to unsafe stimuli. No nervous system complex enough to have such psychological phenomena means no pain. For example, you can reduce a cockroach (similar number of neurons, analogous physiology and anatomy) to basically the nerve trunk in a isotonic solution and it still responds as if the cockroach were whole, alive and "enjoying" a nice bit of PB&J dropped under the cabinet.

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## Stylopidae (Nov 6, 2007)

butch4skin said:


> Or better yet, how do we know that an animal _can_ interpret stimuli through touch as dangerous, yet most likely cannot feel physical pain.





butch4skin said:


> I've always wondered, what's the difference between being able to interpret stimuli by touch as dangerous(which Theraphosids are obviously capable of) and being able to feel pain?



That is all explained here in quite a bit of detail.

You need to know the physical processes that go on when you feel pain, as well as how and where that information is processed.

Then, compare and contrast.

If an animal lacks the opsins that respond to any sort of color, we can safely assume that animal is colorblind. Whether or not an animal feels pain works on similar logic.

_One_ of my posts from that thread on the subject:



Cheshire said:


> Again...this is based upon what?
> 
> 400 year old research?
> 
> ...


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## Travis K (Nov 6, 2007)

*to all the vegitarians*

If it taste good eat it!  Who cares what it feels.  Personally i would love to go to asia and eat one of the many T's they have at some of the venders on the street, nad ship a live one off to the states.  LOL, i have an uncle in Thai Land, i should ask him to ship me some T-kabobs, and maybe some live T's when the weather gets better.

Yeah i always thought it was funny when people say some things can feal pain and others not.

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## Stylopidae (Nov 6, 2007)

Travis K said:


> If it taste good eat it!  Who cares what it feels.  Personally i would love to go to asia and eat one of the many T's they have at some of the venders on the street, nad ship a live one off to the states.  LOL, i have an uncle in Thai Land, i should ask him to ship me some T-kabobs, and maybe some live T's when the weather gets better.
> 
> Yeah i always thought it was funny when people say some things can feal pain and others not.


Nobody's come in preaching yet...hopefully it stays that way.

Don't encourage, don't provoke.


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## problemchildx (Nov 6, 2007)

I like this thread, learned a lot already from you guys!


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## Stylopidae (Nov 6, 2007)

Thanks for the compliment...and for overlooking a huge typo in a vital part of that post


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## butch4skin (Nov 6, 2007)

I knew you meant invertebrates


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## Calucifer (Nov 6, 2007)

Oh my god that thing...
about cockroaches, nerve trunks and isotonic solutions....
That just gave me the creeps

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## lucanidae (Nov 6, 2007)

Ugh.....here we go on this no pain due to primitive nerve system stuff again.  This time I'll just throw out my references first and let you decide for yourself, the author of this paper is Tom Eisner....father of chemical ecology.  He's a very nice old professor I am currently taking a class from here. If you aren't familiar with his work....just do a quick google search.

Here's the paper I want all those who think no invertebrates feel pain to read:

Spider leg autotomy induced by prey venom injection: An adaptive
response to "pain"?

http://www.pnas.org/cgi/reprint/80/11/3382

It should be free for you to download from that page, please let me know if it isn't.

Here's a start:


> Field observations showed orb-weaving spiders (Argiope spp.) to undergo leg autotomy if they are stung in a leg by venomous insect prey (Phymata fasciata). The response occurs within seconds, before the venom can take lethal action by spread to the body of the spiders. Autotomy is induced also by honeybee venom and wasp venom, as well as by several venom components (serotonin, histamine, phospholipase A2, melittin) known to be responsible for the pain characteristically elicited by venom injection in humans. *The sensing mechanism by which spiders detect injected harmful chemicals such as venoms therefore may be fundamentally similar to the one in humans that is coupled with the perception of pain. *


The paper is a very good read, and the author is one of the geniuses of entomology of our time. The discussion is probably the most important part to read.


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## lucanidae (Nov 6, 2007)

Here then, try this on for size;

Another article all the no pain camp should read:
SENTIENCE AND PAIN IN INVERTEBRATES
http://66.102.1.104/scholar?hl=en&lr=&safe=off&q=cache:LU9NJSpLA6MJ:vkm.no/dav/0327284150.pdf+

Some food for thought from it: (This should also answer the original posters question.  The number of threads that don't consider the literature and simply jumped to well established arachnoboards conclusions is very large....this reminds me of the 'spiders don't have pigments' rumor here)


> The central nervous system of spiders has some resemblance to those of crustaceans and insects, but is even more concentrated (Brusca & Brusca 2002). The brain includes a protocerebrum and tritocerebrum connected to ventral nerves, while all the ganglia are more or less fused
> with the brain. In scorpions the ventral nerve cord has seven ganglia.





> As pointed out by Sherwin (2001), we may be mistaken in assuming that invertebrates have a reduced capacity to experience suffering. Suffering is a private experience, or a negative mental state that cannot be measured directly. The responses of invertebrates to noxious conditions are often strikingly similar to those of vertebrates. Several experimental studies have shown that invertebrates such as cockroaches, flies and slugs have short and long-term memory, have ability of spatial and social learning, *perform appropriately on preference tests, and may exhibit behavioural and physiological responses indicative of pain.* *The similarity of these responses to those of vertebrates may indicate a level of consciousness or suffering that is normally not attributed to invertebrates*





> Opioid substances are also known from invertebrates. If their function is similar to that in vertebrates, this is an indication that invertebrates may feel pain, which is reduced by the opioids. At present no certain conclusion can be drawn, but opioids are interesting in considering the question of pain in invertebrates. Examples of the presence of opioids are known from different groups of invertebrates


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## Code Monkey (Nov 6, 2007)

lucanidae said:


> The paper is a very good read, and the author is one of the geniuses of entomology of our time. The discussion is probably the most important part to read.


The bolded part of your quote does not mean what you imply. It simply refers to a sensory feedback system where they are "aware" of the venom's presence prior to significant damage to the area of the sting. It would be more surprising if venoms that evolved prior to a bunch of spined wonders poking into bee hives for a sweet snack didn't elicit sophisticated responses in inverts. After all, they've had a lot longer to engage in their physiological selection warfare than those of us who go "OW!" or, even, "HOWL!".

Sensing and responding to damage, even if in a relatively sophisticated manner, does not imply a pyschological ability to suffer. Otherwise, this is all semantic masturbation where people try to define pain as something other than that (its most common and, for that matter, legal definition). If the ability to "feel pain" is defined as anything other than psychological suffering then, sure, go nuts with the inverts feel pain. So don't bacteria for that matter, which also show preferences and aversions in analogous tests, and they don't even have a nervous system.

But, if you accept the logical premise that awareness, sentience, and full blown self consciousness are an emergent phenomena based in the complexity of the animal's brain, then you've got to be crazy to assume that it's even possible that animals who have fewer neurons in their entire body by an order of several magnitudes than your average vertebrate has in their foot (or equivalent) is anything other than on the cusp of awareness and certainly nowhere near sentience and, therefore, the capability of suffering.

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## lucanidae (Nov 6, 2007)

Is it this bold quote?



> As pointed out by Sherwin (2001), we may be mistaken in assuming that invertebrates have a reduced capacity to experience suffering. Suffering is a private experience, or a negative mental state that cannot be measured directly. The responses of invertebrates to noxious conditions are often strikingly similar to those of vertebrates. *Several experimental studies have shown that invertebrates such as cockroaches, flies and slugs have short and long-term memory, have ability of spatial and social learning, perform appropriately on preference tests, and may exhibit behavioural and physiological responses indicative of pain. The similarity of these responses to those of vertebrates may indicate a level of consciousness or suffering that is normally not attributed to invertebrates.*


or the spider bold quote?

The spider bold quote wasn't supposed to be 'proof' of anything, just a stimulus to get people to read the paper and think for themselves about it.  There seems to be this dominance of one side of the argument on these boards that comes from what seems to be years of no one fact checking on the side that maybe, possibly, and even enough of a question to test for years and years and years over....that these things might feel something like pain. 

I didn't intend for these select quotes to be the end all of this argument on these boards, I of course expected literature counter references (which exist...I found them) and strong defense from many of the people who have called others incompetent on this subject thread after thread.


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## Nivek (Nov 6, 2007)

I know one thing. If they can feel pain, they are nature's biggest bad a**es. Periodically popping out of their own skin and dropping appendages like a bad habit, lol. I don't have any relative information to add to the discussion, but I do have a question to throw out. Does anyone know which invertebrate has the most complex nervous system and such? I always assumed it would be a centipede for some reason.

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## butch4skin (Nov 6, 2007)

Nivek said:


> I know one thing. If they can feel pain, they are nature's biggest bad a**es. Periodically popping out of their own skin and dropping appendages like a bad habit, lol. I don't have any relative information to add to the discussion, but I do have a question to throw out. Does anyone know which invertebrate has the most complex nervous system and such? I always assumed it would be a centipede for some reason.



I would assume it would be some kind of cephalopod, but what do I know? I don't even have a degree.


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## Nivek (Nov 6, 2007)

Haha, cephalopod. I actually knew that. Now that I feel like a complete idiot haha.:wall:


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## Code Monkey (Nov 6, 2007)

lucanidae said:


> or the spider bold quote?


That one.



> I didn't intend for these select quotes to be the end all of this argument on these boards, I of course expected literature counter references (which exist...I found them) and strong defense from many of the people who have called others incompetent on this subject thread after thread.


Having survived my graduate degree in entomology with a healthy chunk of that involving invertebrate physiology and neurology, I neither want to get into a literature citation search (not that you asked), nor do I have the slightest suspicion that any of the non-cephalopod invertebrates can actually suffer, and I'd call even cephalopods a healthy stretch.

I think people underestimate the complexity of their minds and what they're capable of, but to attribute suffering in a meaningful context is to cheapen what the concept means. A few invertebrate biologists wanting to quibble about where to draw the line smacks more of either too much subjective bias or someone deliberately wanting to stir the pot to get publications noticed, not anything I'd remotely consider honest, scientific inquiry. The evidence just isn't there in the basic physiology. Someone can speciously point out that we don't have a good way of directly measuring suffering, but we can look at those life forms we know as close to certain as possible do experience genuine psychological suffering and compare what they use for their cognitive capabilities to something like a tarantula. It's like comparing the words, "I ran fast", to the sum total of the Library of Congress and declaring "I ran fast" a masterwork on par with it.

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## Stylopidae (Nov 6, 2007)

Code_Monkey and I have come to identical conclusions through very different routes of study.

He has gone through a graduate study program, I've been doing independant study since I was 5 years old.

I'll be the first to admit that you're far more qualified than I am, Lucanidae but I've also got to say that nothing in those papers (quick scan is all I can afford for now) points to the conclusion that invertebrates can feel pain in a similar way to what we can. Feeling actual *pain* in the way that CM and I are defining it (see my previous posts) and feeling something *like* pain are two completely different things.

Bacteria and cnidarians also show preferances and could show responses to pain like stimuli, if you defined pain loosely enough. Sure they can sense and react to things we would consider painful, but in my own experience with insects (watching about a dozen or so being dismembered by various animals every day) nothing indicates to me they can feel pain.

They have fight or flight reactions and they will certianly make an attempt to get away from something that can do them harm, but even we have similar reactions to similar stimuli where we don't actually feel pain at the time of the reaction (covered in my other posts in that thread).

As for the other side being called incompetent, I don't ever remember writing the words but also can't deny I wasn't thinking it.

The 'bugs can feel pain' side usually consists of over-emotional hobbiests who usually know nothing about the physiology of invertebrates and who have no desire to learn anything about that physiology. They feel an overwhelming need to be able to share some sort of bond with their pets and the desire to have that bond will outweigh any evidence contrary to the conditions required to fulfull that desire to have that bond.

You're the first person to say bugs can feel pain who's arguments weren't composed entirely of various logical fallacies. I think that's very respectable.

However, like Code_Monkey said...I also think that research you posted has motivations other than empiricism. Not to say I won't read it but I just don't see how a tarantula that weighs about a quarter of what my entire brain weighs would feel anything similar to what I feel...especially given what (little) I know about the invertebrate neurobiology. I have more neurons in a teaspoon of my grey matter than my entire lobster roach colony has...the types of information that I can process and the types of information they can process can't even be similar.

Yes folks...the entirety of what I've posted is probably taken care of in the first week of any neurobiology course.

Okay...decided to read the papers instead of working on a chemistry lab.

Stupid, I know...but I'm too tired to comprehend the stuff I'm required to do for chemistry.

First paper:



> But when defined operationally as a physiological
> phenomenon induced in an animal by stimuli that are painful
> to us and resulting in a protective stimulus-avoidance response
> in that animal, pain is amenable to testing with nonhuman subjects.


This made me laugh. Why?

What they are doing is essentially saying that if it's painful to us and results in a reaction, then we can test whether or not it's pain.

Pretty logical, right?

Well, look at the statement right before it:



> Pain, in the sense of a consciously perceived experience, remains
> a subjective notion applicable to humans but untestable
> with animals.


They flat out say that the notion of whether or not invertebrates can feel pain is essentially untestable (I don't really think it is...but I laid my argument out months ago), but then follow it up with saying 'but if it's painful to us, then we can use that to test whether or not invertebrates can feel pain if they react to the same stimulus'.

Well 20 molar hydrochloric acid is definitely painful to me and there's no doubt it would also produce a flight reaction from a jellyfish, but that's hardly something to base your argument on. Any sane bacterium would taxis away from that acid as fast as their little flagella could carry them. They're assuming a-priori that an invertebrate would feel something similar to what we feel despite the fact they have a vastly different nervous system and the way they're basing their argument could be applied to a variety of species with rediculous results.

A biochemical response to the venom is a far more likely explanation in my opinion...spiders that predated on venomous insects caught in their webs who autonomized legs in response to various compounds in different compositions of venom passed on the genes that made them more likely to do so in response to those chemicals. They didn't mention any evidence of the spiders suffering...just throwing legs. I've never said spiders can't react to negative stimuli.

Throwing a leg in response to mechanical damage alone would certianly be disadvantageous...the spider wouldn't be able to wrangle prey nearly as effectively (and possibly put the spider in a bad situation...the seventh phymatid) and I'm sure there are many predators that would cause minor mechanical damage to the spider in a matter that wouldn't be considered signifficant enough to throw a leg.

Of course, there's the last sentance of the paper:



> But one spider-the common house spider
> Achaearanea tepidariorum (family Theridiidae)-proved exceptional
> in that it never autotomized (n = 11 spiders) despite
> its evident susceptibility to envenomization (7 of 11 died).
> ...


So spiders can sense venom, but there was no evidence presented that those signals even made it to the ganglion or that the spiders suffered as a result. Only that they can sense venom when it's injected and that they're able to react to that venom. This is a behavior that does not require any degree of suffering to execute.

On to the second paper.

From your second paper:



> Invertebrates react in different ways to detrimental stimuli (Fiorito 1986). The reactions do not necessarily in itself indicate any experience of pain, but more an activation of the central nervous system to produce avoidance or escape reactions. For example, due to mechanical stress, the spider Argiope sp. may react with leg autotony, and the crab Carcinus mediterraneus with alarm display.


Which is what I've been saying all along.

In terms of invertebrates and pain, the second paper says that subjective experiences are untestable but also that it's reasonable to assume that invertebrates can't feel pain for the _exact reasons I outlined in posts months upon months ago_.



> On the question of pain in insects, Eisener et al. (1984) pointed out that it is not possible to give a conclusive answer since the subjective experienced of an organisms cannot be registered. Still, from considerations of the insect nervous systems and their behaviour there does not appear to be any support to the occurrence of pain. Several examples are known in which insects continue with normal activities even after severe injury (Eisener et al. 1984, Smith 1991). An insect walking with a crushed foot will apply it to the substrate with undiminished force. Locusts [vandregresshopper] have been seen to continue feeding whilst being eaten themselves by preying mantis [kneler], and aphids continue to feed when eaten by coccinelid beetles [marih?. A male mantis continues to mate although eaten by his partner, and a tsetse fly will try to suck blood although half dissected during an experiment. Many adult insects and larvae continue to develop whilst being eaten by large internal parasitoids. It appears that there is no evidence of conscious experience in insects, since natural selection of a capacity for pain would also result in corresponding capacity for adaptive responses. Furthermore, it is argued that although some insect behaviour, such as the convulsions of insects poisoned by DDT, the struggling of restrained insects, repellent secretion and alarm pheromones, resembles that of higher animals responding to pain, no more requires the presence of pain sense than reflexive withdrawal. In spite of these strong arguments against pain in insects, more research is wanted. Some authors think that it is presumptuous for us to assume that because our human suffering involves self-awareness, this should also be true in other species.


CM and I have dealt with that last statement already, but I wanted that paragraph to be in context.

The paper then goes on to rehash the same argument, that subjective experiences are untestable which I've already countered by explaining that pain requires a certian physiology which is not present in the animals you and I are discussing.

I do find the fact that opioid substances effect invertebrates in a similar way to you and I interesting, however I don't think that really indicates pain even though it does decrease their sensitivity to noxious stimuli.

The opioid argument is very convincing, however the role they play in the nervous system needs to be studied more thoroughly before the conclusion can be made that invertebrates can feel pain. From the evidence I've listed above, I don't think it would be surprising to hear that the opioids would play a role in moderating stress.

Remember that an animal can feel stressed without suffering. An anemone that is disturbed too much will eventually die.

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## Xamec (Nov 7, 2007)

Have heard similar things about fish, "they have no nerves in their mouths".  Ever pull a barbed hook out of a fishes mouth?:wall:


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## Code Monkey (Nov 7, 2007)

Xamec said:


> Have heard similar things about fish, "they have no nerves in their mouths".  Ever pull a barbed hook out of a fishes mouth?:wall:


The difference here is that "they have no nerves in their mouth" is a fallacious statement.

That said, it's still unlikely they actually *suffer*, so it's still unlikely you can declare they feel pain. This, though, is based in the complexity of their brains - which are still magnitudes more sophisticated than the brains of tarantulas and yet still considered as incapable of basic emotion.


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## Stylopidae (Nov 7, 2007)

Xamec said:


> Have heard similar things about fish, "they have no nerves in their mouths".  Ever pull a barbed hook out of a fishes mouth?:wall:





Code Monkey said:


> The difference here is that "they have no nerves in their mouth" is a fallacious statement.
> 
> That said, it's still unlikely they actually *suffer*, so it's still unlikely you can declare they feel pain. This, though, is based in the complexity of their brains - which are still magnitudes more sophisticated than the brains of tarantulas and yet still considered as incapable of basic emotion.


Exactly. From what I've read, most biologists are still out on whether or not they can actually feel pain.

After you pull that hook from the fish's mouth and put it in your livewell or a fishtank, it returns to normal pretty damn quick...within seconds. In fact, the fish always seem to be more worried about finding a place to hide rather than the wound in their mouth. Their appetite always returns to normal within a few minutes and there is no reluctance to eat as we would expect to see in a teenager who just got their tongue peirced.

Whether or not they have nerve endings in their mouths is irrelevant...whether or not you can feel pain depends on how your brain is set up, as well as it's complexity.

Whether or not an animal can feel pain has to do with the size of a part of the animal's brain called the Cerebral cortex. The larger it is, the more complex functions it can perform. Pain is actually a very complex function and I don't think there's the type of awareness required to feel pain (as per the _relevant_ definition I laid out in the thread I linked to awhile ago) until we get to the reptiles. Possibly the amphibians...I haven't really bothered to research their brains all that much for some reason.

Of course, the next statement I can predict from the other side is that I'm implying that it's OK to torture inverts, fish and the like because it's very likely they don't feel what we would recognize as pain.

If you're planning on making that statement, bite me. I dealt with that in the previous thread which you obviously haven't read.


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## Xamec (Nov 7, 2007)

I don't want to get into a big thing here but a lot of people used to argue that anything not human couldn't feel pain.  Pain is the biological response to damage, if an animal responds to part of itself being damaged, it's feeling pain.  Animals like tarantulas may not react in the same way as humans when they get one of their legs crushed, because the tarantula can regrow a leg.  As humans can't regrow lost limbs, the response to something like that is shock, which would kill you (hopefully) before the scavengers tore you apart.  I don't care what all the scientists in the world think about this.


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## Stylopidae (Nov 7, 2007)

Xamec said:


> I don't want to get into a big thing here but a lot of people used to argue that anything not human couldn't feel pain.


This was back 400 years ago...something I've mentioned with one of my other posts. We've learned a lot about what makes the brain tick since then and we know exactly how pain is felt and what takes place when pain is felt.

The mechanisms behind pain are very well understood.



> Pain is the biological response to damage, if an animal responds to part of itself being damaged, it's feeling pain.


No...that definition is so broad as to be irrelevant. Poriferans and bacteria both move away from things that are harmful to them, but both lack a central nervous system. I keep bringing up cnidarians because they have nerve cells, but no nervous system. They, too can react to stimuli but cannot feel pain because they lack a central nervous system.

You can react to something that is potentially harmful and not feel pain. If you've ever put your hand on an unexpectedly hot stove, you know this. You'll pull away before you feel anything (most times). The signal doesn't make it to your brain before you react...this is called a somatic nerve arc.

The definition of pain I gave in the thread I linked to is the legal definition of pain used by neurologists who study how pain is felt. It's relevant.

All you're doing is expanding a definition to cover what you want it to. Under your definition mitosis is also considered pain because that is also a response to some types of physiological damage.

Right now, you have billions of cells dividing all over your body...is that painful?



> Animals like tarantulas may not react in the same way as humans when they get one of their legs crushed, because the tarantula can regrow a leg.  As humans can't regrow lost limbs, the response to something like that is shock, which would kill you (hopefully) before the scavengers tore you apart.


I also explained what traumatic shock was in that thread. During traumatic shock, activity in the cerebellum and related areas decrease due to decreased blood flow. That is why pain is not felt.

Guess what?

Most inverts (excluding cephalopods because this conversation focuses squarely on insects/spiders) don't have those areas. Do the math. You've damaged your own position.

Inverts that can't regrow limbs (such as adult cockroaches) show _no_ reaction to major or minor injuries...at least not one indicative of pain. Code_Monkey gave a great example earlier...you can remove the entire nervous system of a cockroach and it will still respond as if nothing had happened.

The dozens of other examples I gave also render this post irrelevant. Observations simply don't reflect what you're saying. A caterpillar being eaten alive from the inside out will show no reaction, while something as small and relatively harmless (compared to the parasitoid) as a tapeworm will basically immobilize a human until it's removed.

They can react to damage, but there is no evidence they can suffer. Reacting to damage and suffering are two different things.

The one _good_ bit of evidence I've seen so far was Lucanidae's paper mentioning the opioids, but that argument is relatively weak until we know what the function of those compounds is in the invertebrate nervous system. There are still other non pain related functions they could correlate to.



> I don't care what all the scientists in the world think about this.


Then why bother debating? Why not try to learn something?

Why go through life seeing what you think is there and not once try to figure out what's really going on?

If you don't care about what people who study this stuff for a living...people who spend hours a day hunched over a microscope trying to figure this stuff out have to say on the topic, then why even bother putting your two cents in?

All you really want is for the world to conform to your preconcieved notions and that is the most empty way to live your life.

Read through this thread and when you can formulate a well thought out and informed response I'll be more than happy to take you seriously.


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## Code Monkey (Nov 7, 2007)

Xamec said:


> Pain is the biological response to damage, if an animal responds to part of itself being damaged, it's feeling pain.


Cheshire already responded, but this was so funny as to warrant another response.

Pain is NOT the biological response to damage, pain is strictly a psychological phenomon (which arises from biological processes, but it is by no means _the response to_, rather it is a secondary effect of negative stimuli). The biological responses to damage are things like taxis, immune system stimulation, increased/decreased blood flow, nerve impulse propogation, release of stimulatory compounds like adrenaline or increases in the glucose supply, etc. What you, I, and our dog would call pain is another layer of adaptation on top of what you are erroneously calling pain. What you are calling pain is simply the capacity to respond to negative stimuli, it is indicative of nothing going on in the mind of an animal, which is what is the relevant issue. As animals, including us, have placed more and more of their functioning into more and more sentient minds, pain is what has developed as a way of involving those varying levels of sentient minds. Without some sort of sentient mind, you have stimuli-response, not pain, and as in the fish example, even when you begin to have some level of actual mind it is still by no means clear that said mind is capable of anything that can seriously be considered suffering/feeling pain.

If nothing else will appeal to your squishy feely mindset, consider how dedicated meditators can approach pain. The sensation itself cannot be stopped, but the sensation itself can be simply sensed in the mind without the psychological reaction. The same nerve signals are there, the suffering is not. The "ow ow ow, ohhhh it hurts, oh jebus, make it stop..." is a secondary phenomenon in sufficiently complicated minds to a lower level biological process - take away the sufficiently complicated mind and guess what?


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## Xamec (Nov 7, 2007)

I thought that post would open up a can of worms.  I don't like endless debates, so this will be the last time I post on this.  My point is basically this: because you or I can never have the experience of being one of those animals that "can't feel pain", we can really only speculate on what they can or can't feel.  I imagine that a living thing that has a "negative reaction" to a damaging stimulus feels something akin to what I would feel, unsophisticated or not.  I also think scientists don't fully understand everything in the biological world as yet.  I love science and biology, but this is the one area that I disagree with.


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## Code Monkey (Nov 8, 2007)

Xamec said:


> because you or I can never have the experience of being one of those animals that "can't feel pain", we can really only speculate on what they can or can't feel.


People can't be photons or hydrogen atoms either, but I figure you won't argue we can't measure empirical information about them. Somehow it's just the alive things that the scientific method stops working for, huh? The gap in reasoning is your "we can only speculate", no, we can do a lot more than speculate. We can measure nerve impulse propogation in the neurosystems, we can analyse electron microscope images of slices of their brains, we can contrast and compare throughout the animal kingdom. It is NOT mere speculation (mere speculation is what you're doing), it is the best answer based on a lot of people working on similar problems going back longer than any of us have been alive. Just because we can't be the tarantula doesn't mean we can't categorically say that after how many ever nerve impulses in how many ever nerve clusters and ganglia have been measured in them and similar nervous systems throughout the world that there hasn't been one accepted fact generated that would lead people to conclude anything other than that their minds are too limited to have the capacity of suffering. Technically, being science, it doesn't mean we *know* they're not suffering, but it does mean that somebody's going to have to demonstrate an entirely new neurobiology model that contradicts everything brain surgeons, clinical psychiatrists, and neurologists are out there working with, so, being science, it means we can reasonably put the possibility of suffering into the same likelihood as Russel's celestial teapot.



> I love science and biology, but this is the one area that I disagree with.


Then you don't actually have any confidence (or love) of science. That's what science is: the best possible answer based on all the evidence at any given time. It is not something you pick and choose from like the produce aisle at the Super Wal-Mart. If you suspect something is wrong, then you do your own study (or at least come up with a published rebuttal) to try and disprove or weaken accepted hypotheses, you don't decide that since you can't be a honey bee you get to assume that everything we know is simply wrong. 

For example, you're more than happy to come into this thread about whether a tarantula actually has a brain and accept that science tells us they do. You're more than happy to let science tell you what the different parts of the brain control. But let the same science that got you this far disagree with your baseless world view, and suddenly it must be wrong.


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## DrAce (Nov 8, 2007)

lucanidae said:


> ...
> Another article all the no pain camp should read:
> SENTIENCE AND PAIN IN INVERTEBRATES
> http://66.102.1.104/scholar?hl=en&lr=&safe=off&q=cache:LU9NJSpLA6MJ:vkm.no/dav/0327284150.pdf+


The final conclusion to this document, states:


> In conclusion, it appears that most invertebrates probably are unable to feel pain.


Good lord, CM, you're good at this!

I must say that this is one of the best worded posts I've read on this board, with respect to science, and, quite frankly, I doubt I could word his sentiments any better.

Well done.  I agree with every word and punctuation mark!



Code Monkey said:


> People can't be photons or hydrogen atoms either, but I figure you won't argue we can't measure empirical information about them. Somehow it's just the alive things that the scientific method stops working for, huh? The gap in reasoning is your "we can only speculate", no, we can do a lot more than speculate. We can measure nerve impulse propogation in the neurosystems, we can analyse electron microscope images of slices of their brains, we can contrast and compare throughout the animal kingdom. It is NOT mere speculation (mere speculation is what you're doing), it is the best answer based on a lot of people working on similar problems going back longer than any of us have been alive. Just because we can't be the tarantula doesn't mean we can't categorically say that after how many ever nerve impulses in how many ever nerve clusters and ganglia have been measured in them and similar nervous systems throughout the world that there hasn't been one accepted fact generated that would lead people to conclude anything other than that their minds are too limited to have the capacity of suffering. Technically, being science, it doesn't mean we *know* they're not suffering, but it does mean that somebody's going to have to demonstrate an entirely new neurobiology model that contradicts everything brain surgeons, clinical psychiatrists, and neurologists are out there working with, so, being science, it means we can reasonably put the possibility of suffering into the same likelihood as Russel's celestial teapot.
> 
> Then you don't actually have any confidence (or love) of science. That's what science is: the best possible answer based on all the evidence at any given time. It is not something you pick and choose from like the produce aisle at the Super Wal-Mart. If you suspect something is wrong, then you do your own study (or at least come up with a published rebuttal) to try and disprove or weaken accepted hypotheses, you don't decide that since you can't be a honey bee you get to assume that everything we know is simply wrong.
> 
> For example, you're more than happy to come into this thread about whether a tarantula actually has a brain and accept that science tells us they do. You're more than happy to let science tell you what the different parts of the brain control. But let the same science that got you this far disagree with your baseless world view, and suddenly it must be wrong.


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