Emotion in animals

Emotion is defined as any mental experience with high intensity and high hedonic content. The existence and nature of emotions in non-human animals are believed to be correlated with those of humans and to have evolved from the same mechanisms. Charles Darwin was one of the first scientists to write about the subject, and his observational (and sometimes anecdotal) approach has since developed into a more robust, hypothesis-driven, scientific approach. Cognitive bias tests and learned helplessness models have shown feelings of optimism and pessimism in a wide range of species, including rats, dogs, cats, rhesus macaques, sheep, chicks, starlings, pigs, and honeybees. Jaak Panksepp played a large role in the study of animal emotion, basing his research on the neurological aspect. Mentioning seven core emotional feelings reflected through a variety of neuro-dynamic limbic emotional action systems, including seeking, fear, rage, lust, care, panic and play. Through brain stimulation and pharmacological challenges, such emotional responses can be effectively monitored. Emotion has been observed and further researched through multiple different approaches including that of behaviourism, comparative, anecdotal, specifically Darwin's approach and what is most widely used today the scientific approach which has a number of subfields including functional, mechanistic, cognitive bias tests, self-medicating, spindle neurons, vocalizations and neurology. While emotions in nonhuman animals is still quite a controversial topic, it has been studied in an extensive array of species both large and small including primates, rodents, elephants, horses, birds, dogs, cats, honeybees and crayfish. The word "emotion" dates back to 1579, when it was adapted from the French word émouvoir, which means "to stir up". However, the earliest precursors of the word likely date back to the very origins of language. Emotions have been described as discrete and consistent responses to internal or external events which have a particular significance for the organism.