Evolution of emotion

The study of the evolution of emotions dates back to the 19th century. Evolution and natural selection has been applied to the study of human communication, mainly by Charles Darwin in his 1872 work, The Expression of the Emotions in Man and Animals. Darwin researched the expression of emotions in an effort to support his theory of evolution. He proposed that much like other traits found in animals, emotions also evolved and were adapted over time. His work looked at not only facial expressions in animals and specifically humans, but attempted to point out parallels between behaviors in humans and other animals.

According to modern evolutionary theory, different emotions evolved at different times. Primal emotions, such as fear, are associated with ancient parts of the brain and presumably evolved among our premammal ancestors. Filial emotions, such as a human mother's love for her offspring, seem to have evolved among early mammals. Social emotions, such as guilt and pride, evolved among social primates. Sometimes, a more recently evolved part of the brain moderates an older part of the brain, such as when the cortex moderates the amygdala's fear response. Evolutionary psychologists consider human emotions to be best adapted to the life our ancestors led in nomadic foraging bands.

Darwin's original plan was to include his findings about expression of emotions in a chapter of his work, The Descent of Man, and Selection in Relation to Sex (Darwin, 1871) but found that he had enough material for a whole book. It was based on observations, both those around him and of people in many parts of the world. One important observation he made was that even in individuals who were born blind, body and facial expressions displayed are similar to those of anyone else. The ideas found in his book on universality of emotions were intended to go against Sir Charles Bell's 1844 claim that human facial muscles were created to give them the unique ability to express emotions. The main purpose of Darwin's work was to support the theory of evolution by demonstrating that emotions in humans and other animals are similar. Most of the similarities he found were between species closely related, but he found some similarities between distantly related species as well. He proposed the idea that emotional states are adaptive, and therefore only those able to express certain emotions passed on their characteristics.

...
Wikipedia