Animal behaviorist Jonathan Balcombe argues that one reason we should radically alter the way our society treats animals is their capacity for pleasure.

From HuffPost:

HuffPost caught up with Balcome not long after HSU’s recent conference on the science of animal thinking and emotions, to find out about more about what we now know, and don’t, about our furry friends and their scaly counterparts — and what he sees as the “enormous” implications of these findings.

Do animals feel pleasure? How do we know one way or another?

Animals certainly do feel pleasure! We can tell they do by observing what happens on the outside — how they behave. And by observing what happens on the inside — how their physiological states change. Skeptics sometimes claim that we can’t “know” if an animal feels pleasure because their feelings are private, but the same can be said of our fellow humans yet we don’t conclude that we therefore might not be able to feel pleasure.

What are the most recent discoveries about animal pleasure? Are there animals who people used to think didn’t feel pleasure, but who we now think do?

Here’s a scientific one and an anecdotal one. A research team in Portugal found that surgeonfishes who are feeling stressed spend more time up against a mechanical wand that strokes their skin than do fishes who have not been stressed. This was not presented as pleasure, per se, but my interpretation is that the soothing, pleasure of being touched is what helps to relieve stress. Anecdotally, one can watch monkeys “cliff-diving” off a large rock on the coast of Thailand here.

This is just one of many examples of monkeys leaping into water, and I think it conveys the same sort of thrill we get when we dive from a perch, speed down a slope, etc.

Are there any animals who don’t feel pleasure?

This is really a question of where do we draw the line on animal sentience — the capacity to experience feelings. As science reveals ever greater feats of cognition and emotion in an expanding range of animals, we have had to discard old beliefs that denied feelings to most animals. Currently, the evidence is strongly supportive that all vertebrate animals have feelings that should include pleasure. And evidence is building that at least some invertebrates, including cephalopod mollusks (octopus, squid, etc.) and crustaceans (crabs, lobsters, etc.) can experience pain. If an animal can feel pain, then I believe it is equipped also to feel pleasure.

Read more here.