A study published in scientific journal The Royal Society this month found that pigs make optimistic and pessimistic decisions, much like humans, based on their moods. Researchers divided 36 pigs among two mood-setting environments, a basic housing unit and an “enriched” unit where pigs were given a deep straw sleeping area and larger space allowance. All pigs were presented with two food bowls—one containing sweet treats and the other coffee beans—placed in varying locations within their respective environments. Over the course of several weeks, researchers observed how all of the pigs responded when they encountered a treat (sweets) as opposed to a deterrent (coffee). “Those living in a worse environment were more pessimistic and those in a better environment were more optimistic,” the study states. “Importantly, this finding demonstrates that humans are not unique in combining longer-term personality biases with shorter-term mood biases in judging stimuli.” While pigs continue to be used in animal testing and consumed as food, the complexity of pig intelligence has been the subject of several other studies, including a comprehensive one published in International Journal of Comparative Psychology last year that found pigs have a robust memory, recognize their friends, and can play fetch.