Evolution of emotion

Evolutionary explanations for the existence of discrete emotions such as fear and joy are one of many theoretical approaches to understanding the ontological nature of emotions. Historically, evolutionary theoretical approaches to emotions, including basic emotion theory, have postulated that certain so-called basic emotions (usually fear, joy, anger, disgust, and sadness) have evolved over human phylogeny to serve specific functions (for example, fear alerts a human mind of imminent danger). So-called basic emotions are often linked causally to subcortical structures of the brain, including the amygdala (pronounced uh-MIG-duh-luh). In other words, subcortical structures have historically been considered the causes of emotions, while neocortical (neo- meaning new, recent and cortical meaning relating to cortex) structures, especially the prefrontal cortex, are almost invariably understood as the cause of reason. Those ideas about the brain are old; they're traceable at least to Aristotle and were later incorporated into Paul MacLean's mistaken model of brain organization, the "triune brain." These ideas have led to the widespread, erroneous belief that animal brains, including human brains, evolve in a linear fashion, such that, along the course of evolution, new layers of brain tissue are stacked upon older layers of brain tissue, much like the formation of sedimentary rocks. Brain evolution is a lot more complicated than that.

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 materialist theory of unguided evolution. He proposed that much like other traits found in animals, emotions apparently 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.

Evolutionary psychologists consider human emotions to be best adapted to the life our ancestors led in nomadic foraging bands.