The answer to this question seems, almost certainly, to be yes.
God and bio-mechanics
The argument that fish feel no pain runs along these lines… Fish, crustaceans and insects lack the brain structures necessary to feel pain. They are – essentially – too stupid to be able to experience pain. They live their experienced lives by simple reflexes, without the involvement of higher brain functions.
This very human-centric view of animals (and their experienced lives) probably has distant origins in religious teachings, which gave humans “dominion over the Earth”. Humans are special.
In modern forms, the argument that fish feel no pain is based mostly on bio-mechanical reasoning – but it is still very human centric. Humans are the yardstick against which we still measure the value and abilities of other animals.
But the bio-mechanical viewpoint ignores all the psychological and evolutionary factors. And, for me, it is these factors that make the argument that ‘fish don’t feel pain’ deeply unconvincing. Why so?
Giving and receiving
Quite a few fish can deliver painful/venomous stings to deter predators (the Stonefish being a notable example). It seems very unlikely that these animals would evolve to deliver painful stings – if other fish feel no pain!
The study of cephalopods (especially octopus species) over the last 20 years has revealed that many beliefs about the neurological ingredients for ‘intelligence’ are wrong. Despite having neural structures that are quite different from those of vertebrate species, the cephalopods are capable of some impressive feats of problem solving. And if scientists were wrong in their beliefs about what is necessary for ‘intelligent’ behaviour, might they also be wrong about what is necessary for experienced pain?
Psychology and evolution
First, we can reach conclusions about pain from simple observation of animals’ behaviour. If we stimulate animals (of every kind) with the physical things that cause pain to humans, they respond by trying to escape. For example, if you give a fish a mild electric shock, it will try to escape from that shock.
Moreover, nearly all animals can be taught (and will learn) to avoid things that are ‘painful’. If a fish gets an electric shock every time it swims near a particular rock, it will learn that association and will try to avoid that rock.
Learning to avoid things even before experiencing an electric shock strongly suggests that fish feel pain.
Second, we can reach conclusions about pain from the fact that many animals produce emotional displays.
All animals capable of displaying emotional reactions to pain sources do so. These displays are often similar to human emotional displays. Mammals often howl, scream and/or pull faces, like we do. Undoubtedly this attracts their mothers’ attention to provide protection or care.
Fish and crustaceans make no sounds. And they do not have expressive faces (in common with many aquatic mammals). But to assume from their blank faces that they don’t feel pain is to apply human-centric logic.
What we can say about fish and crustaceans is that they do display other signs of fear. Typically, they flee or hide. Fear, of course, is not a pleasant emotion. We know that when humans feel fear and anxiety they experience something very like pain (a “living hell” as people often put it when a child or pet is missing). Sometimes, when fear takes the form of panic, fear can be extremely painful.
Fear motivates animals to escape from or avoid things that cause them that fear. Since fish, crustaceans and almost every other animal on the planet display signs of fear, it seems very likely that they endure the painful experiences that result from fear.
But to my mind, the third and most compelling argument for ‘fish feel pain’ is the simple evolutionary one.
Pain evolved in humans and other species because it is so adaptive. Pain greatly increases our chances of survival because it warns us about things we must do – and about things we must not do. Internal pains warn us when we need to eat and drink. Pain tells humans not to breathe when under water. Pain – almost certainly – warns fish that they cannot breathe when they are out of water. It is pain that warns us when something is to too hot to touch. Those very rare people who are born without any sense of pain tend to live short lives. And if pain is useful for us to survive, it is almost certainly useful for other animals.
Indeed, it is arguable that other species might actually feel pain more than humans. By evolutionary logic, ‘less intelligent’ species are more dependent on pain than humans to warn them of damage. What we can say for sure is this. Pain improves any species’ chances of avoiding damage – to breed and pass on that innate capacity for feeling pain to the next generation. Why on earth wouldn’t fish, crustaceans and insects have evolved to experience pain??
But, of course, none of us is a fish. We can’t absolutely prove what they do or do not feel (any more than I can know absolutely what any other human feels).
However, the evolutionary logic is compelling… If there is a warning system (pain) that can warn humans when they are being damaged, the probability is very high that it will have evolved in every other species that has a capability to escape from damage. That means, essentially, any species that can move.
Plants and trees?
And this leads us on to plant life. Do trees and plants feel pain? In my view, the evolutionary logic says no. Experiencing pain would not bring an evolutionary advantage to a tree. Trees are rooted solidly in the ground, giving them a potential to outlive every animal on Earth. But that comes with a price. Rooted so solidly, trees cannot escape from fire or the chainsaw. The experience of pain would bring them no advantage.
Believing what we want to believe
Some people simply don’t mind about animal welfare or pain, unless it affects the flavour. Others feel great guilt and become vegans. And this offers us a good example of the biases that affect how we use science.
The science we choose to believe is often the science that tells us things we want to hear, rather than things that are true. It is much easier to lower a lobster into a pan of boiling water if we believe that it doesn’t hurt it at all!