Emotion in animals
Emotions in animals are the subjective feelings and emotions experienced by nonhuman animals. Emotions may be described as subjective, conscious experiences characterized primarily by psychophysiological expressions, biological reactions, and mental states.Charles Darwin was one of the first scientists to write about the existence and nature of emotions in nonhuman animals. His observational and sometimes anecdotal approach has developed into a more robust, hypothesis-driven, scientific approach. General hypotheses relating to correlates between humans and non-human animals also support the claim that non-human animals may feel emotions and that human emotions evolved from the same mechanisms. Several tests, such as cognitive bias tests and learned helplessness models, have been developed. Cognitive biases (feelings of optimism or pessimism) have been shown in a wide range of species including rats, dogs, cats, rhesus macaques, sheep, chicks, starlings, pigs and honeybees.Some behaviourists claim stimulus–response models provide a sufficient explanation for animal behaviours that have been described as emotional, and that it is unnecessary to postulate that animals are conscious. Other behaviourists further question whether animals feel emotions on the grounds that emotions aren't universal even among humans, that interpretations of animal behaviour are anthropomorphic, and that definitions of emotions lack robustness.