Minds without spines: Evolutionarily inclusive animal ethics

Invertebrate animals are frequently lumped into a single category and denied welfare protections despite their considerable cognitive, behavioral, and evolutionary diversity. Some ethical and policy inroads have been made for cephalopod molluscs and crustaceans, but the vast majority of arthropods, including the insects, remain excluded from moral consideration. We argue that this exclusion is unwarranted given the existing evidence. Anachronistic readings of evolution, which view invertebrates as lower in the scala naturae, continue to influence public policy and common morality. The assumption that small brains are unlikely to support cognition or sentience likewise persists, despite growing evidence that arthropods have converged on cognitive functions comparable to those found in vertebrates. The exclusion of invertebrates is also motivated by cognitive-affective biases that covertly influence moral judgment, as well as a flawed balancing of scientific uncertainty against moral risk. All these factors shape moral attitudes toward basal vertebrates too, but they are particularly acute in the arthropod context. Moral consistency dictates that the same standards of evidence and risk management that justify policy protections for vertebrates also support extending moral consideration to certain invertebrates. Moving beyond a vertebrate-centered conception of welfare can also clarify foundational moral concepts in their own right