I think it’s best to assume all animals can experience affect. I realize this discussion has the potential to transport us from the land of science to the land of ethics, coming perilously close to moral issues such as pain and suffering in laboratory animals, creatures who are factory-farmed for food, and whether fish feel pain when a hook enters their mouth. The natural chemicals that relieve suffering within our own nervous systems, opioids, are found in fish, nematodes, snails, shrimps, crabs, and some insects. Even tiny flies might feel pain; we know that they can learn to avoid odors
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