High Quality Content by WIKIPEDIA articles! Emotion in animals considers the question of what emotions certain species of non-human animals feel, in the sense that humans understand it. The debate concerns primarily mammals and birds, although emotions have also been postulated for other vertebrates and even for some invertebrates.Different answers have been suggested throughout human history, by animal lovers, scientists, philosophers, and others who interact with animals, but the core question has proven hard to answer since we can neither obtain spoken answers, nor assume anthropomorphism. As a result, on the one hand society recognizes animals can feel pain, by criminalizing animal cruelty. Often expressions of apparent pleasure are ambiguous as to whether this is emotion, or simply innate response, perhaps to approval or other hard-wired cues. The ambiguity is a source of much controversy in that there is no certainty which views, if any, are "right". That said, extreme behaviorists would say that human "feeling" is also merely a hard-wired response to external stimuli.In recent years, research has become available which expands prior understandings of animal language, cognition and tool use, and even sexuality.