Rats laugh, bees roll balls for fun, turtles dance when they anticipate feeding, and dogs wiggle their tails when they’re excited. Research into animal emotions and experience has been on the rise since the late 20th century, and scientists are beginning to use these findings to help understand an age-old question: Do nonhuman animals have consciousness?

How should we deal with this lack of certainty? Should we assume that an animal is conscious until proven otherwise or that it is not until we find enough consciousness markers?

Typically, scientists assume that consciousness is absent unless evidence demonstrates it is present. But if such a vast number and wide range of animals now have at least a realistic possibility of consciousness based on existing evidence, then it does raise the question whether we should [instead] have a neutral starting point or proceed on the assumption that consciousness is present unless a lot of evidence indicates it is absent.

Combined with markers of pain and perception, markers of joy can give us better understanding of consciousness. If animals have a realistic chance of being conscious, then we have both ethical and scientific reasons to look beyond pain.