Two Questions

[Malachy]

A couple things just popped into my head earlier today. Can anyone help me out here?

 

1. I was arguing with my friend a couple weeks ago on the morals of veganism, and he was seriously not listening to any reason, and when he asked why I ate fish when I was a vegan I said they didn't feel pain...he said that was just a myth, and I honestly couldn't find a reputable source that said otherwise. So, can fish feel pain?

 

2. I know that Lamarck's theory of passing on acquired traits and use/disuse has since been disproven in many cases, but isn't there a chance that it's at least slightly true? If umpteen generations of organisms used their bodies in a different, similar way; couldn't they alter their parts? Wouldn't the chicken's loss of the ability of flight be an example of this? Sorry if I'm way off here...just a daydream sort of thing.

 

Thanks in advance for your answers.

[BenSon]

To anwer question 1 yes they do feel pain, most of their pain sensors are actually in their mouth so the hook would well you get the idea.

I saw this in a documentary they injected small amounts of bee venom into the lips of fish. They then started rubbing their lips on things trying to remove the pain. Previously in was thaught that fish only sensed pain not how we know it as discomfort but rather as just a safety mechanism that let them know their bodies were damaged. By seeing the fish trying to aleviate the pain or discomfort we know that they don't just register pain as damage but they feel it in similar ways as we do. As for question two i have no idea.

 

~Scott

[Glider]

It's not possible that fish feel pain in the same way we do. Our experience of pain is generated largely in the limbic areas of the brain. Fish have no limbic brain.

 

The experiment involving the injection of bee venom into the lips of a fish resulted in the fish "rubbing their lips on things". That's all that can be said. to say that this behaviour was an attempt to 'remove pain' is a guess. Pain is non-observable and what was observed was just a behaviour.

[BenSon]

I am not suggesting that fish feel pain in exactly the same way as us emotionally ect. What would you say the 'behaviour' is then if not to aleviate the pain. This was a pretty convincing doco but after some searches on the limbic brain i can see what your saying are you sure no fish have a limbic system (i couldn't find much info on that). There is still alot we don't know about the brain perhaps other ares process emotion in animals that we are not aware of.

 

~Scott

[Glider]

I am not suggesting that fish feel pain in exactly the same way as us emotionally ect. What would you say the 'behaviour' is then if not to aleviate the pain.

It could interpreted as anything; e.g. a triggered response to remove an 'irritation', perhaps more usually caused by parasites (where 'irritation' is not pain). The point is, saying what the behaviour is will always be an interpretation.

 

This was a pretty convincing doco but after some searches on the limbic brain i can see what your saying are you sure no fish have a limbic system (i couldn't find much info on that).

Yep. The limbic brain emerged in the first mammals and remains limited to mammals. Fish have elements of the limbic system, but mainly those associated with motivated behaviours, i.e. the three 'F's (fighting, feeding and reproduction).

 

You could looke here for a bit of background

 

http://www.reptilianagenda.com/brain/br121804g.shtml

 

There is still alot we don't know about the brain perhaps other ares process emotion in animals that we are not aware of.

 

~Scott

The funny thing about the brain is that whilst you are quite right, there is so much about the brain that we don't understand, those bits we do understand tend to be universal. I.e. the thalamus (for example) in humans, performs the same functions as the thalamus in all other animals.

[BenSon]

Great link! I stand corected

 

~Scott

[Mokele]

I disagree that fish or other animals without a limbic system cannot feel pain, since, as you put it, pain is usually inferred.

 

I actually recently attended a very good talk on pain and animals, which opened a lot of interesting doors.

 

Firstly, it differentiated pain from simple nocciception, in a variety of interesting ways. The speaker noted that detection of noxious stimuli is universal, even bacteria do it, so it can't truly be called "pain". Furthermore, he noted that, with precisely the right dose of morphine, a human or a mouse can remain conscious of noxious stimuli, but lack the pain associated (such as when humans at this dosage report they can feel the doctors doing things, and they know it hurts, but they feel no pain). Also, he pointed to a series of experiments with spinalized mice that used negative conditioning to their posterior, and got learning, even though there was no pain involved (because of the severed connection to the brain) and no conscious awareness.

 

However, he also noted that mice doped with that "nocciception but no pain" dosage of morphine, while they could learn via classical means, could not learn via operant conditioning involving pain. If these results truly mean that pain (rather than simple nocciception) is required for operant learning with painful negative reinforcement, then we can more easily test to see if animals truly can feel pain, simply by seeing if they can learn under such conditions.

 

---------

 

I agree that non-mammals have a different perception of pain than we do, but I'm hesitant to say they do not feel pain at all, or that their different pain is somehow "less" than ours (I realize you didn't say that, I'm merely expounding my position using yours as a jumping-off point).

 

My experiences with "lower vertebrates", while admittedly annecdotal, do seem to indicate some level of conscious pain (different though it may be). Post-operative behavior of reptiles, for instance, clearly indicates attempts to minimize pain (taking extreme measures not to rest on healing incisions for example). For a more funny example, I'd contend (a bit jokingly) that there has to be some level of brain involvement for my tegu to take the input stimulus of a vet giving him an injection in the base of the tail and produce the seemingly spiteful behavior of tail-whipping him in the eye (even if the brain is only being used to use sight to target the tail motion). He was *not* a happy lizard.

 

Mokele

[Glider]

I disagree that fish or other animals without a limbic system cannot feel pain' date=' since, as you put it, pain is usually inferred.

 

I actually recently attended a very good talk on pain and animals, which opened a lot of interesting doors.

 

Firstly, it differentiated pain from simple nocciception, in a variety of interesting ways. The speaker noted that detection of noxious stimuli is universal, even bacteria do it, so it can't truly be called "pain". Furthermore, he noted that, with precisely the right dose of morphine, a human or a mouse can remain conscious of noxious stimuli, but lack the pain associated (such as when humans at this dosage report they can feel the doctors doing things, and they know it hurts, but they feel no pain). Also, he pointed to a series of experiments with spinalized mice that used negative conditioning to their posterior, and got learning, even though there was no pain involved (because of the severed connection to the brain) and no conscious awareness.

 

However, he also noted that mice doped with that "nocciception but no pain" dosage of morphine, while they could learn via classical means, could not learn via operant conditioning involving pain. If these results truly mean that pain (rather than simple nocciception) is required for operant learning with painful negative reinforcement, then we can more easily test to see if animals truly can feel pain, simply by seeing if they can learn under such conditions.[/quote']

These results cannot mean that pain is required for operant learning.

 

If you look at the examples you provide, they contradict each other. On one hand you say that spinalised mice show evidence of learning with the application of negative reinforcement (I'm assuming you mean the application of a noxious stimulus here. Negative reinforcement is a completely different thing. It refers to the removal of an aversive stimulus or state.), even though there is no spinal connection between the posterior spine and the brain, and on the other hand you say the analgesic doses of morphine negate this form of learning? This makes no sense, because pain cannot be a factor in either experiment.

 

If there is no physical connection between the posterior spine and the brain, then application of noxious stimuli to the posterior of the mouse will not result in pain, or any form of learning involving the brain. However, it can demonstrate 'spinal learning'. In any event, due to the lack of any physical connection between the spine and the brain, there is no way we can conclude that 'pain' was a factor because pain (being an experience) is a function of higher CNS processes, not spinal.

 

---------

 

I agree that non-mammals have a different perception of pain than we do, but I'm hesitant to say they do not feel pain at all, or that their different pain is somehow "less" than ours (I realize you didn't say that, I'm merely expounding my position using yours as a jumping-off point).

The human pain experience is composed of several components: We have the sensory-discriminative component, which allows us to determine the location, duration and intensity of the stimulus. There is also the cognitive-evaluative component, which is what that stimulus 'means' to us in terms of probable outcome. Finally we have the affective-motivational component which is our emotional response to the stimulus and the resulting behavioural drive to remove it (or remove ourselves from it). The affective-motivational and cognitive components are what constitute the 'suffering' associated with human pain. Opioid analgesia effectively knocks out the suffering component. It does have some influence on the nociceptive pathways (dorsal horn and projection neurons) but the strongest influence of morphine is in the limbic regions.

 

If you take organisms that have no limbic brains to speak of, then you must question the degree to which they can experience the affective, or 'suffering' component of pain.

 

My experiences with "lower vertebrates", while admittedly annecdotal, do seem to indicate some level of conscious pain (different though it may be). Post-operative behavior of reptiles, for instance, clearly indicates attempts to minimize pain (taking extreme measures not to rest on healing incisions for example). For a more funny example, I'd contend (a bit jokingly) that there has to be some level of brain involvement for my tegu to take the input stimulus of a vet giving him an injection in the base of the tail and produce the seemingly spiteful behavior of tail-whipping him in the eye (even if the brain is only being used to use sight to target the tail motion). He was *not* a happy lizard.

 

Mokele

Many experiments in pain have been conducted on rats, using the 'tail-flick' response as a measure of pain. Rats do have limbic brains (as do all mammals), but even then, to observe a rat chosing to flick its tail away from a noxious stimulus and then to say the rat felt pain is a huge assumption.

 

Humans respond to mosquito bites in such a manner (almost an automatic response to an irritant), but it cannot really be said that mosquito bites are painful, although they are very irritating.

[Mokele]

If you look at the examples you provide, they contradict each other. On one hand you say that spinalised mice show evidence of learning with the application of negative reinforcement (I'm assuming you mean the application of a noxious stimulus here. Negative reinforcement is a completely different thing. It refers to the removal of an aversive stimulus or state.), even though there is no spinal connection between the posterior spine and the brain, and on the other hand you say the analgesic doses of morphine negate this form of learning? This makes no sense, because pain cannot be a factor in either experiment.

 

That would be because I evidently buggered up the explanation. This is Mokele's brain on insufficient sleep...

 

The experiments I so poorly described were separate. The one with the spinalized mice (suspended over an electrified plate, so they'd be shocked if they let their legs relax) showed that spinal learning can occur with just classical conditioning and without conscious awareness of pain. The second experiment had morphine-doped mice in a two part cage, one part of which was electrified but evidently had something desirable about it (I forget what). The non-doped mice learned to stay away from the electrified room, but the doped ones didn't, even though they could detect the noxious stimuli (but not the 'pain' in the brain). It seems to me to be saying that, without 'pain', the mice won't learn avoidance of nociceptive stimuli operantly. (But this isn't my field by a long shot, and I'm recalling from a seminar speaker several months ago.)

 

If you take organisms that have no limbic brains to speak of, then you must question the degree to which they can experience the affective, or 'suffering' component of pain.

 

I'd agree they might not experience it the same way we do, yes, but I strongly disagree that means they don't experience it at all, especially if pain (like the mice experience) is needed for aversive operant learning.

 

If there is one thing evolution teaches us, it's that there's more than one way to skin a cat (or in this case, wire a brain). Octopi display lots of mental traits that "higher" organisms do, but their brains look *nothing* like any chordate's. The portion of a crocodile's brain that we'd assume is dedicated to learning and thought seems small, yet one species is a pack hunter which seems to be "smarter" in that area than wolves (though nobody has yet done conclusive studies on this, in part due to the sheer danger of such studies, since they most often display this behavior when hunting their keepers). Just because a brain seems to lack areas that mammals use for certain tasks, does not mean it cannot perform those tasks. And the sheerplasticity of the human brain in terms of broad functions merely underscores how easy it would be for areas to change function over evolutionary time, especially between highly divergent lineages.

 

That's my main objection, the idea that just because mammals use a portion of the brain for something, then therefore that particular part of the brain is necessary for that function to occur at all.

 

Many experiments in pain have been conducted on rats, using the 'tail-flick' response as a measure of pain. Rats do have limbic brains (as do all mammals), but even then, to observe a rat chosing to flick its tail away from a noxious stimulus and then to say the rat felt pain is a huge assumption.

 

If you'll re-read my annecdote, you'll notice that I said 'tail-whip', which is a very specific, very accurately-targetted defensive behavior, rather than a reflex response. It's usually aimed for the eyes of the attacker, or the limbs, thereby involving the brain, if only to co-ordinate with sensory input. To assume that a voluntary, defensive, targetted behavior involving the brain can be linked to the brain detecting something analagous (though possibly not homologous) to 'pain' is far less of a stretch.

 

-------

 

Mostly, my objection is to the seemingly mammal-centric tone of the assertion that the limbic system is necessary. One would assume that 'pain' has a distinct evolutionary purpose (or is linked to something that does, like operant learning involving painful stimuli) else it would vanish. To then assume that the only ones to capitalize on it are a bunch of comparatively unimportant fuzzballs is, to me, counter-intuitive.

 

An analogy would be to say that because other animals lack the system of malleus, incus and stapes, they cannot hear, when in reality they can hear just fine, simply through a different method (stapes alone).

 

Forgive me if I sound a bit confrontational or anything, but like most non-mammal-centered biolgists, I have a large sore spot when it comes to the over-emphasis of mammals and the assumption that mammals are someone the definitive group when it comes to whatever.

 

Mokele

[Sayonara]

1. I was arguing with my friend a couple weeks ago on the morals of veganism, and he was seriously not listening to any reason, and when he asked why I ate fish when I was a vegan I said they didn't feel pain...

If you eat fish, you are - by definition - not a vegan. You are a pescetarian.

 

 

2. I know that Lamarck's theory of passing on acquired traits and use/disuse has since been disproven in many cases, but isn't there a chance that it's at least slightly true? If umpteen generations of organisms used their bodies in a different, similar way; couldn't they alter their parts? Wouldn't the chicken's loss of the ability of flight be an example of this?

Kind of, by selection.

 

You have to realise that selection works across whole populations (in the main) and dozens (if not more) of generations. Lamarckian acquisition is supposed to be a direct parent->child change.

[invert_nexus]

Glider,

 

the three 'F's (fighting, feeding and reproduction).

 

Four. Four F's. You forgot fleeing. And it's not reproduction it's fu... fornication. (Ha! Why can't we just say it?)

 

You could looke here for a bit of background

 

http://www.reptilianagenda.com/brain/br121804g.shtml

 

Wow. What a whackjob website that is. Why would you post something like that as a reference? And why hasn't anyone else commented on it already?

 

 

Anyway, I think it's a bit on the arrogant side to say that fish feel no pain. I'll agree that they don't feel pain as we do and it's even quite possible that the pain they feel is more akin to 'irritation' than what we think of as pain and/or agony, but it's nonetheless an uncomfortable sensation which they don't care for a bit. That's how these things work, you know. Instincts are prompted by sensation. Things that feel bad are avoided and things that feel good are sought after. Why should it be any different for fish?

 

The limbic brain emerged in the first mammals and remains limited to mammals.

 

While this is mostly true, it's not entirely true. You've already admitted that fish and reptiles have some limbic structures, now the question is how much and what effect do they have in the various species.

 

Many of the effects that you are attributing solely to mammals would be exhibited in caring for the young. Most reptiles do not care for their young. They lay the eggs. Sometimes caring for the eggs, sometimes not, but almost always abandoning the young once hatched. However, this is not always the case. There are reptiles who do care for their young. This means that these reptiles are in possession of functions that you are trying to say arose only in mammals.

 

In dinosaurs, this trait was even more common. Many dinosaur species cared for their young. In fact, there is a debate as to whether dinosaurs were cold-blooded reptiles or warm-blooded something else. Birds are a direct descendant from dinosaurs. Wouldn't you find it odd that they should possess structures that only developed in mammals after the reptile and therapsid lineages split? Now that would be some remarkably convergent evolution there.

 

If you take organisms that have no limbic brains to speak of, then you must question the degree to which they can experience the affective, or 'suffering' component of pain.

 

I'll agree with you on this... somewhat. Let's just say that mammals, and especially humans with their enormous frontal lobe, are able to 'appreciate' the pain more. They evaluate and dwell on it rather than just experience as a discomfort. But, this is not to say that the fish doesn't feel pain. It just doesn't appreciate the pain.

 

Humans are so appreciative of pain, in fact, that they don't even need real stimulus to feel it. We are adept at translating practically any stimulus (or lack of stimulus) into pain. We torture ourselves with our frontal lobe.

 

 

BenSon,

 

Great link!

 

You're... kidding. Right?

I mean that site did have some culled information on it but it was so muddled and just plain odd that it screams crackpot a mile away.

 

 

Mokele,

 

The portion of a crocodile's brain that we'd assume is dedicated to learning and thought seems small, yet one species is a pack hunter which seems to be "smarter" in that area than wolves

 

Crocodiles are also one of the reptile species that is known to care for it's young... somewhat.

 

 

 

 

Edit:

Oh. Almost forgot. On the subject of Lamarkian evolution. Try Baldwinian Evolution instead. Behavior affects selection which can imprint behavior into the genome.

[hyebeh]

lamarck's theory is never correct. a organism cannot acquire genetic traits (which are the only traits that natural selection works upon). Therefore, the organism cannot pass the acquired traits (which are not genetic) to its offspring.

[Mokele]

Crocodiles are also one of the reptile species that is known to care for it's young... somewhat.

 

I'm assuming the "somewhat" is in place because they don't care for their young once they've hatched. However, incidentally (and totally off-topic), there is some new evidence showing up that females may hang around the group of babies (which themselves tend to aggregate into a 'creche') for a few months. Still tenuous and debated hotly, and still nowhere near the level of parental care seen in mammals and birds, but interesting nonetheless.

 

Mokele

[invert_nexus]

I'm assuming the "somewhat" is in place because they don't care for their young once they've hatched.

 

Yes and no. I'm far from being a herpetologist or a crocodile expert, but I have seen documentaries showing some limited maternal behavior after hatching. For instance, they gather the hatchlings up in their mouth to carry them to the water. For a crocodile who bites reflexively from pressure on the inside of the mouth, this is a pretty amazing feat. And they also allow them to share the same water for a time after hatching as well.

 

Yes. It's not anywhere near the level of mammalian parental care. But it is something. I am sure that there are other examples as well, but my sleep-deprived brain can't clear the headnoise enough at the moment to think of any concrete examples.

 

lamarck's theory is never correct. a organism cannot acquire genetic traits (which are the only traits that natural selection works upon). Therefore, the organism cannot pass the acquired traits (which are not genetic) to its offspring.

 

Which is why I mentioned Baldwinian Evolution. Look up the Baldwin Effect. Behavior over time tends to solidy genetically. It doesn't happen in a single or few generations, but it does happen.

[hyebeh]

even with baldwin effect, the driving force is still selection and the no traits are developed and then passed on.

[invert_nexus]

No. With the Baldwin Effect traits are passed on. Eventually.

 

Take Vervet monkeys and their well known vocalizations. These vocalizations are genetically inspired. A vervet raised in captivity will make these calls under the proper conditions without needing to be taught them. But, they do need to be taught to refine their technique. The hawk call, for instance, might be used erroneously anytime anything is seen above the monkey. It takes experience to hone that down so that only the proper stimulus produces the proper effect.

 

But, for this behavior to have become instilled into the genetic material of the monkey, it needed to be selected for. Those monkeys that didn't make the proper calls were culled from the population. While those who did make the call were selected for. Over time this solidifies behavior genetically.

 

You have to look at it as a series of small changes. Every behavior of an animal is based on some form of genetic trait at least in some small way. A predilection for behaving one way as opposed to another. And as time goes on and the Baldwin Effect hones the genome this predilection becomes stronger and stronger. More genetically bound. Until it is no longer a predilection, but an instinct.

[Mokele]

Yes. It's not anywhere near the level of mammalian parental care. But it is something. I am sure that there are other examples as well

 

Pythons incubate eggs via shivering (no known post-natal care), and king cobras build nests and guard them (much to the dismay of anyone or anything in the area). Several amphibians engage in parental care, too.

 

Every behavior of an animal is based on some form of genetic trait at least in some small way. A predilection for behaving one way as opposed to another. And as time goes on and the Baldwin Effect hones the genome this predilection becomes stronger and stronger. More genetically bound. Until it is no longer a predilection, but an instinct.

 

I disagree; there are some behaviors that are purely learned, with no innate component, such as stick-fishing in termite mounds by chimps, or opening jars via octopi. The most you could say for any of these is that the animals are wired for the capacity to learn. Sometimes it's a bit narrower, like with songbirds which have a critical period during which they can learn their species' song, but learning must still play a role.

 

I agree that gene-based behaviors can become more intense and totally fixed, but without that initial basis, I don't think it can happen.

 

Mokele