March 11, 20255 min readThe Secret to Understanding Animal Consciousness May Be JoyAnimal emotionsincluding joymay be key markers of conscious beingsBy Jacek Krywko edited by Sarah Lewin FrasierThis chihuahua may be having a joyful experience. Stuart Lark/Getty ImagesRats laugh, bees roll balls for fun, turtles dance when they anticipate feeding, and dogs wiggle their tails when theyre 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?Consciousness is often defined as having subjective experiences. We are focusing on this particular kind of phenomenal consciousnessthat it feels like something to be you, says Jeff Sebo, a philosopher and director of the Center for Environmental and Animal Protection and the Center for Mind, Ethics, and Policy, both at New York University. If you can have subjective feelings, either sensory experiences like perception or affective experiences like pleasure or pain, that is what we call consciousness.Sebo, along with philosophers Kristin Andrews and Jonathan Birch, initiated the New York Declaration on Animal Consciousness. Released in April 2024, it has been signed by more than 500 scientists and researchers worldwide. The same trio recently co-authored an essay in Science arguing that when animals perform behaviors similar to those that are explained by conscious experience in humans, such as joy, suffering and other emotions, that can begin to suggest animals conscious experience, too.On supporting science journalismIf you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.Scientific American talked with Sebo about what the potential markers of consciousness are, whether we should assume a species is conscious unless proven otherwise and how scientists might study consciousness through markers of animal joy.[An edited transcript of the interview follows.]How can looking for markers of joy or pain help us determine if animals are conscious?Consciousness is such a difficult topic to study. It confronts us with the hard problem of explaining why any physical system, including our own brain, should be conscious, as well as the problem of other mindsthe problem that the only mind I can directly access is my own. That makes it hard for me to know for sure what, if anything, it feels like to be anyone else, even other humans. So instead of attempting to solve the hard problem of consciousness or the problem of other minds, we identify behavioral and anatomical markers that are consistent with a range of leading scientific theories of consciousness. And then we search for those markers in animals.You would start by using introspection to distinguish between conscious and unconscious experience in humans. We can look inward and tell when we are experiencing conscious pain versus having an unconscious nociceptive response. We then look for observable behavioral or anatomical markers or indicators that are associated with conscious processing in humans, and we can then look for broadly analogous behavioral or anatomical markers or indicators in animals.Obviously, they are not going to be proof of consciousness. They are not going to establish certainty about consciousness, but we can treat them as evidence. And when we find a lot of markers or indicators together in an animal, that can take up the probability that consciousness is present.So the final step would be to estimate at least a rough probability of consciousness based on how many behavioral and anatomical markers we find in that animal. Establishing high, medium, even low probability of consciousness can be a helpful step toward making informed decisions about how to study that animal or how to interact with it.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.My colleague Kristin Andrews, who wrote the Science essay with me and Jonathan Birch, has argued that we in fact should flip the default assumption to the presence of consciousness in animals. That we should presume animals are conscious and then research the dimensions of that consciousness.[She argues that] this assumption is good not only ethically, because it represents a kind of precautionary stance toward our interactions with animals, but also scientifically, because it leads to better and more rigorous hypotheses about the nature of consciousness and the dimensions of consciousness that we can then research.You suggest animal consciousness research is overly reliant on pain markersintentionally inflicting pain to see how animals respond to it. Does presuming consciousness complicate this practice?We use pain markers to assess the probability that particular animals can consciously experience negative states like pain and suffering. You can ask basic questions like: Do they nurse their own wounds? Do they respond to analgesics or antidepressants in the same ways that humans do? Do they make behavioral trade-offs between the avoidance of pain and the pursuit of other valuable goals like finding a new shell or finding food? And to the extent that they do behave that way, we can become more confident that they can experience pain and suffering. This gives us information about how we might change our interactions with them in ethics and policy.But if animals have a realistic chance of being conscious, there should be ethical safeguards on how pain markers are used. We can look at past studies [investigating] the presence or absence of pain markers. We can also conduct observational field research and use observations of animals experiencing pain and nursing their wounds in the wild without intentionally inflicting pain. We can still use pain markers if we collect them ethically.The advantage of using pain markers is that they are easy to observe. How do you study joy?There are at least some markers of joy that appear to be quite widespread across animals. One is vocalizations that resemble laughter. Quite a few species will vocalize in a way that indicates joyful experience. Rodents can vocalize ultrahigh-frequency sounds in response to play or tickling in a way that resembles laughter.Another example is optimism. You can perform studies that give animals the opportunity to pursue the unknown. If they pursue it more readily then that suggests an optimistic outlook. If they pursue it less readily, then that suggests a pessimistic outlook. Optimism is generally associated with positive experience, positive affect.Then there is play. We see play behavior in a lot of different animals. It does not have an obvious direct evolutionary advantage, but it seems to be an expression of joy. We find that not only in other mammals, like dogs, but even in insects. There is research involving bees rolling a ball around for no other reason than the sort of positive experience associated with it.And there are other joy markers that are going to be more species-specific, like facial expressions or tail-wagging. Finally, there are some other markers, too, such as the presence of oxytocin or dopamine or serotonin in the brain.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.