There's an interesting article in the Guardian that reports on a study, the conclusion of which is that lobsters are unable to feel pain. This, of course, must sadden Animal Rights activists in general, and those of the Lobster Liberation Front in particular. The Guardian tells us:
It is the ethical dilemma that for decades has troubled the rich and aspiring the world over: when you place a live lobster in a pot of boiling water, does it feel pain?
Norwegian scientists were asked to investigate pain, discomfort and stress in invertebrates and claim now to have discovered that the answer is no.
Their conclusion applies also to crabs and to live worms on a fish hook. None of these feel a thing. Which is good news for Norwegian fishermen at least.
Their government was considering a ban on live worms as fish bait under revisions to its animal protection laws - but only if it hurt. Wenche Farstad of the Norwegian School of Veterinary Science in Oslo now says it does not.
"It seems to be only reflex curling when put on the hook. They might sense something but it is not painful and does not compromise their well-being," said Prof Farstad, who chaired the panel that prepared the government report. "The common earthworm has a very simple nervous system. It can be cut in two and continue with its business."
The report looked at welfare implications of everything from cooking live crabs and lobsters to keeping bees. Invertebrates are animals without backbones, covering creatures from insects and spiders to mollusks and crustaceans.
Honeybees deserve special care, Prof Farstad said, because they display social behaviour and a capacity to learn and cooperate. But invertebrates do not feel pain because they have basic nervous systems and small brains.
Peter Fraser, a marine biologist at the University of Aberdeen, says crabs and lobsters have only about 100,000 neurons, compared with 100bn in people and other vertebrates. While this allows them to react to threatening stimuli, he said there is no evidence they feel pain.
Tiny perforations in leg bones allow crabs and lobsters to jettison limbs if trapped by predators. "That doesn't demonstrate whether they feel pain or not, but it does demonstrate they have very different mechanisms," Dr Fraser said. "If we tried to throw off a leg I'd imagine that would be very painful indeed."
Well! If only life were so simple as to ask a scientist — or an ideologue — and receive a definitive answer, one beyond questioning!
Alas, it is not so.
Readers of AC will know that I am particularly turned off by the false logic of "proving a negative." Scientists cannot prove that lobsters don't feel pain any more than you can prove that humankind isn't the product of a curious liaison between space aliens and swamp grass . . .
On the other hand, there is compelling evidence to suggest that lobsters don't experience sensation the way we do. For one thing, as the Norwegian scientists point out, lobsters have precious few neurons (100 thousand vs. 100 billion for some mammals, ourselves included) to be able to sense much at all. Plus, the organization of the lobster nervous system is far different from that of vertebrates: rather than having a spinal cord and brain where integration and association occur, lobsters have a simple, primitive system consisting of several discrete paired clusters of nerve cell bodies (ganglia) that control, well, everything.
The fact that lobsters and other invertebrates respond to noxious stimuli with movement tells us nothing about what a lobster can "feel."
We know, for example, that humans with complete spinal cord transection retain deep tendon and withdrawal reflexes below the level of the transection. This is important because the patient is unaware of the sensation causing the reflex (the patient moves, but is incapable of feeling what stimulated the movement or preventing the movement from happening).
We also know that the vertebrate spinal cord is capable of generating rhythmic, stereotyped "on-off" commands that underlie repetitive motor function like breathing and walking. For example, if a cat's spinal cord is separated from its brain (where "feeling" is), the isolated spinal cord can generate coordinated stepping movements.
The rhythmic commands are derived from networks of nerve cell bodies and their processes, which are located in the spinal cord, which "talk" to one another in a self-sustaining way, and which can function independent of the brain and independent even of sensation itself (each such network is called a "Central Pattern Generator") or CPG. And, a greater or lesser number of CPGs can be recruited by the brain to enable increasingly complex movements.
We know that old patterns and connections can be "forgotten" if not practiced, and that new patterns can be learned through repetition (repetitive sensation can reprogram the spinal cord — meaning new connections form, a phenomenon known as "nervous system plasticity").
So — where does all this leave us?
The observations in humans with injured spinal cords and the experiments on animals tell us that you cannot infer that a vertebrate can "feel" anything simply by observing that it responds with movement to a stimulus.
It's a huge stretch to extrapolate from humans to invertebrates — as in lobsters — when the two nervous systems are so different both in quantity (number of neurons) and quality (spinal cord plus brain versus paired ganglia), and the criterion being compared ("pain") is so subjective.
(This is not to say that you can't use invertebrates for certain kinds of biomedical research, research that helps us understand normal and abnormal human processes and anatomy — you certainly can. You just have to be aware of the limits.)
Finally, we shouldn't lose sight of the fact that plants can sense and respond to innocuous and noxious stimuli. They can also communicate with members of their own species, as well as with plants of other species, sometimes miles away.
(For more on the question of "feeling," response to stimuli and plant communication, see my earlier post "Lobsters, Plant Pain, Plant Rights")
The take-home message from the present post is this: the evidence does not support the assertion that lobsters feel "pain."
Movement in response to noxious stimuli is poor indicator of "feeling pain" since we know that plants can move in response to stimuli, and that the isolated spinal cord of vertebrates, both human and non-human, can generate movements in the absence of consciousness.
The burden of proof is squarely on those who claim lobsters can feel pain to do so.
Thanks to David S. for the tip.