Humans have had relationships with their pets for thousands of years, talking to them, coddling them, and imbuing them with human attributes. But are these animals “thinking,” and do nonhuman animals have the same sorts of feelings that humans have? Most people with pets would say “yes.”

What does the science say? In recent decades, researchers have begun to find scientific answers to questions of consciousness for a variety of species. The broad consensus is that many animals are sentient (have conscious thought), that there are different types of cognition, and that a larger number of animals require protection and more research is needed for a wider range of species.

At an April 2024 meeting at New York University, 39 prominent scientists from different disciplines issued “The New York Declaration on Animal Consciousness,” emphasizing “strong scientific support for the attributions of conscious experience to other mammals and to birds” and “at least a realistic possibility of conscious experience in all vertebrates (including reptiles, amphibians, and fishes) and many invertebrates (including, at minimum, cephalopod mollusks, decapod crustaceans, and insects).”

The declaration, signed by 480 scientists as […]