On this topic, highly recommend this book, which provides a rather different perspective: https://www.goodreads.com/en/book/show/50403455-metazoa https://www.g

On this topic, highly recommend this book, which provides a rather different perspective: https://www.goodreads.com/en/book/show/50403455-metazoa https://www.goodreads.com/en/book/show/50403455-metazoa Breaking it down - what we think of as pain perception is not one thing but several, as you'd expect for one of the major functions in a ninety-giganeuron brain. There's something not much more than a low-level reflex response - "Ouch" - and most animals have that. There's wound-grooming behaviour, which is mostly linked to capacity to heal, and shows up in perception as the longer-lasting (minutes to days/weeks) pain from an injury. A lot of animals with exoskeletons have very limited healing capacity, so there's no point in attempting to heal. This is thought to be why, for example, a severely and probably fatally damaged ant will just keep on trucking, whereas even the simplest mammals and reptiles will attempt to rest and heal. Then there's awareness of mortality. Simply, an animal that doesn't know it's alive can't connect pain to the concept of death. To what extent this exists across the animal kingdom is one of the great unknowns. And then finally there's placing a value on one's life (and so negative value on harm to it), and the way in which we humans understand that is intimately bound up with concepts like love, grief, friendship, family and so on - these likely exist for animals that care for their young. Those are traits mostly limited to higher vertebrates, and it's not entirely clear to what extent birds and mammals have a common ancestor with that capability (therefore some commonality in "experience") or whether that's convergent evolution. It's pretty clear that it exists across all mammals, but has independently developed to much higher levels in the most intelligent ones (cetaceans, elephants, apes), despite these groups being very far apart on the mammal tree of life, having diverged almost at the origin of placental mammals (which makes more sense when you consider what a placenta is for). So what the pain experience is "like" for a hive-society animal like Hymenoptera (bees, wasps, ants), where caste roles are biologically determined, is impossible to say, if indeed there is any experience there. The skin (or exoskeleton) they have in the game is so different to ours that it's hard to reason about it.