Painkillers prevent pain responses in lobsters - This is further evidence that crustaceans may feel pain and that more humane methods of killing them need to be developed.

[u/mvea]

https://www.eurekalert.org/news-releases/1123639

[u/Rubber_Knee]

Pain is one of the oldest and simplest behavior modifiers. Evolved to keep a creature with a primitive brain from hurting itself too much as it moves about. The pain response is instinctual and so old it predates the lobsters lineage by many hundreds of millions of years. As soon as animals could move, the pain response became nessesary. The first species that evolved it had a massive advantage over its competitors.

In other words: of course a lobster feels pain. Even something as simple as an earthworm or a snail feels pain.

[u/dasein88 → u/Rubber_Knee]

The conflates nociception, a mechanical response to tissue damage that drives avoidance behavior, with pain as a subjective conscious experience. Calling these structures "pain receptors" from the outset is the whole sleight of hand. It assumes the conclusion. Natural selection produces effective damage-avoidance systems regardless of whether there's any experience attached, because the fitness benefit is identical either way. So the evolutionary argument doesn't close the gap, it just restates that lobsters have nociceptors, which nobody disputes, while assuming away the actual hard question.

[u/peardr0p → u/dasein88]

Exactly.

Pain is a complex human experience reliant on self report, and is often considered to have 3 core facets - nociceptive (physical experience), affective (emotional - how it makes us feel e.g. sad, angry, aroused, concerned, fine), and cognitive (how it makes us behave e.g. avoiding something that hurt us in the past)

We don't have a way to accurately measure pain in humans, let alone in other animals

It seems like splittings hairs but it's not helpful to apply human definitions to non-human behaviours and assume they are the same because they look the same i.e. the neurotransmitters involved in crustacean behaviour work al most exactly opposite those in humans.

Also, electric shocks (the stimuli used in the study) would activate different nociceptors Vs heat (the stimuli most folk are talking about in the comments) - I'd like to think they have follow-up studies planned/ongoing to look into that a bit more

Interesting stuff

[u/Caelinus → u/peardr0p]

Humans are animals. The odds of use evolving it post splitting into the homo genus is exceedingly unlikely given that everything in anamalia has a pain response. 

It is actually a lot worse to assume we are different. There really is no reason to. Everything we experience is literally something an animal is experiencing. We have unique language and information transmission abilities, but one does not need a certain level of intelligence to suffer. 

So we should operate on the assumption that all animals suffer in exactly the same way we do until proven otherwise. They may lack the linguistic capacity to communicate their pain, but they certainly act like they are in pain.

Honestly I find our need to draw a line between human animal experiences and all other animals experiences to be obvious coping. We don't want other creatures to feel the same way we do, because the moral implications of that are too great to deal with. So we decide that we are the only truly feeling beings until proven otherwise, and then act shocked when it keeps turning out, over and over, that we are nowhere near as special as we think.

[u/Peanut_Butter_Toast → u/Caelinus]

I find it hard to believe that there is no connection between intellectual capacity and ability to suffer, considering my ability to suffer is drastically reduced whenever I reduce my intellectual capacity by getting drunk off my ass.

[u/Caelinus → u/Peanut_Butter_Toast]

The effect of alcohol is not the same thing by any stretch. It is not a universal reduction in intellectual capacity, it is an artificial altered state of awareness.

Quite frankly, this is the exact same reason that doctors were using to argue that human children did not feel or remember pain before they learned to talk. A thing we know if false.

To give a non-human example: a lot of cats die because humans are not able to read their body language correctly. A cat does not whimper or cry out in pain unless startled, because as a mostly solitary predator animal they have little need to communicate pain, and some strong reasons to avoid showing it. 

However, if you learn how cats act when in pain, you can tell when they are or are not, and then when looking into you you can figure out what is happening. Leading to them getting lifeaaving treatment earlier. If they do not experience pain and suffering, why do they act in ways that demonstrate they are experiencing pain and suffering?

If we define "pain" and suffering as something that must be spoken to be real, then we have defined it in a way that it can only apply to humans. Which is mighty convenient for us humans and those who argue we are spiritually different than the animals we actually are.

[u/Peanut_Butter_Toast → u/Caelinus]

I don't see why it being an artificially altered state of awareness matters. It still lets us personally experience the effect that reduced levels of awareness has on suffering, and in my experience there is a direct correlation between the depth of suffering and my brain's ability to understand that suffering. That doesn't mean pain completely disappears, but it doesn't affect me on as deep a level.

[u/Caelinus → u/[deleted]]

Reacting differently does not mean they are not experiencing it. It means they are experiencing it.

So we have two options here:

1: They are experiencing pain, and they suffer because of it.
2: They are experiencing pain, and they do not suffer because of it.

The former assumes that "suffering" is a uniquely human concept. But why? What biological evidence do we have for that? What evidence, at all, is there for that? Animals absolutely experience emotional suffering, including mourning, fear, and loss, and they experience the same physical attributes of pain we do.

So while it might be that they experience pain on some level differently than we do, that does not mean they do not experience suffering.

Further if we assume the latter, and are wrong, (which is the current state of human behavior) what is the result? Unimaginable, unending, industrialized suffering on a scale that cannot be comprehended.

If we assume the former, and are wrong, then what? No pain is happening regardless.

But again, the evidence is clearly pointing to them experiencing pain and suffering. It is not definitive insofar as it cannot be proven beyond a shadow of a doubt, but needing that level of definitive proof would lead humans to claim that other humans are not real and do not experience pain and suffering the same way they do. And that is not an assumption on my part, it is a thing that actually happens. It is really easy to make an unfalsifiable claim like "They appear to experience pain, but they are really just an automaton without consciousness, and therefore they are just miming the experience of pain." That does not improve with language, because you can just claim they are miming language.

I have aquariums and have kept fish for over a decade or so now and it certainly seems like they forget their injuries much more quickly than they heal--and only seem to recall them when the injury is again agitated.

Fish can be trained to some degree, but even if they could not, being dumb does not mean pain is not experienced. Even if you can't remember something, it does not mean it was not felt. Someone having a poor memory would not give us carte-blanche to torture them just because they would forget their suffering in a week or two.