An item at the CNN website reports that a study from Queen’s University, Belfast suggests that crabs “feel” pain.
The study, by researchers Bob Elwood and Mirjam Appel, examined the behavior of hermit crabs subjected to electric shocks. Hermit crabs, as I am sure you know, live in the abandoned shells of other animals, and what the researchers did was to wire up their shells, give them a jolt, and see how they reacted. If the shock was strong enough, the crab would pop right out, but if it was just below this threshold, the crab would still have a higher likelihood of moving to a new shell when one was offered than crabs who hadn’t been shocked: presumably it remembers the shock and wants to avoid getting another.
What this result indicates, then, is that electric shocks influence the behavior of crabs. The spin here seems to be, however, that hermit crabs consciously experience the shocks — that they suffer — and that therefore we have a moral obligation to avoid causing them pain. While this may also be true, it is a far more audacious claim, far less certain, and raises some difficult questions.
How expensive is consciousness? How valuable is it? What machinery is required to generate it? It is easy enough to see the adaptive value of detecting threats to the body and reacting aversively toward them; were I designing a little hermit-crab robot, one of the systems I’d put in the spec would be a way of detecting when the shell I had chosen was no longer a safe place, and some routine for moving to a new shell when needed. No consciousness would be necessary for this, though; all it would take would be some sensors, and some logical “flags” for them to set in the operating system. If this design were enough to get the job done, expensive extra features like consciousness might not be worth the cost. There’d be nobody “in there” actually suffering; there’d just be a little crab-shaped robot (a “zombie”, in philosophical parlance) moving to a new shell. If consciousness is indeed expensive, and Nature parsimonious, then I would imagine that actual crabs are no more conscious than my little robot.
But if consciousness is not expensive — if it arises naturally, say, from even simple nervous systems — then the moral-obligation assertion begins to gain traction. My own feeling, given how labile and gappy even human consciousness is, and how easily deleted, is that consciousness is an expensive feature indeed, and unlikely to be needed in a crab.
But then we must ask: well then, what exactly do we need consciousness for?
It’s all too much for a late Sunday night, I think. Read the story here.