Evolution of emotion
The study of the evolution of emotions dates back to the 19th century. The theory of evolution and natural selection has been applied to the study of human communication, mainly by Charles Darwin in his work, The Expression of Emotions in Man and Animals (1872). Charles Darwin researched the expression of emotions in an effort to support his theory of evolution. He proposed that much like other traits found in humans and animals, emotions also evolved and were adapted over time (Hess and Thibault, 2009). His work looked at not only facial expressions in both humans and animals, but attempted to point out parallels between behaviors in animals and in humans.
Origins
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 what Sir Charles Bell (1844) claimed about human emotions—saying that in humans, muscles were created to give humans the unique ability to express emotions (Hess and Thibault, 2009). The main purpose of Darwin's work was to support the theory of evolution by demonstrating that emotions in humans and 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 genes (Darwin, 1872).
Darwin's Principles
In the 1872 work, Darwin proposed three principles. The first of the three is the "principle of serviceable habits," which he defined as useful habits reinforced previously, and then inherited by offspring. An example that Darwin (1872) used is the contracting of eyebrows (furrowing the brow), which he noted is serviceable to prevent too much light from coming into the eyes. He also said that the raising of eyebrows serviceable to increase the field of vision, even with nothing to be seen. He cited examples of people attempting to remember something and raising their brows, as though they could "see" what they were trying to remember.
The second of the principles is that of antithesis. While some habits are serviceable, Darwin proposed that some actions or habits are carried out merely because they are opposite in nature to a serviceable habit, but are not serviceable themselves. Shrugging of the shoulders is an example Darwin used of antithesis, because it has no service (Darwin, 1872). Shoulder shrugging is a passive expression, and very opposite of a confident or aggressive expression.
The third of the principles is expressive habits, or nervous discharge from the nervous system. This principle proposes that some habits are performed because of a build-up to the nervous system, which causes a discharge of the excitement. Examples include foot and finger tapping, as well as vocal expressions and expressions of anger. Darwin noted that many animals rarely make noises, even when in pain, but under extreme circumstances they vocalize in response to the pain and fear (Darwin, 1872).
Relevant Research
Paul Ekman is most noted in this field for conducting research involving facial expressions of emotions. His work provided data to back up Darwin's ideas about universality of facial expressions, even across cultures. He conducted research by showing photographs exhibiting basic expressions of emotion to people and asking them to identify what emotion was being expressed.
In one particular study, Ekman and Wallace Friesen, (1971) presented people in a preliterate culture a story exhibiting a certain emotion along with photographs of specific facial expressions. They were then asked to choose from two or three choices of photographs the correct emotion being expressed in the story. The photographs had been previously used in studies involving Western cultures, and were correctly guessed most of the time. Their results indicated that certain expressions of emotions are universally associated with emotions, even in instances in which the people had little or no exposure to Western culture. The only emotions the preliterate people found hard to distinguish between were fear and surprise (Ekman and Friesen, 1971). Ekman (1993) noted that while universal expressions do not necessarily prove Darwin's theory that they evolved, they do provide strong evidence of the possibility. He mentioned the similarities between human expressions and those of other primates, as well as an overall universality of certain expressions to back up Darwin's ideas. The expressions of emotion that Ekman noted as most universal based on research are: anger, fear, disgust, sadness, and enjoyment (Ekman, 1993).
Carroll Izard, a psychologist who is known for his work with emotions, discussed gains and losses associated with the evolution of emotions. He noted that in evolution, humans gained the capability of expressing themselves with language, which contributed greatly to emotional evolution. Not only can humans articulate and share their emotions, they can use their experiences to foresee and take appropriate action in future experiences. He did, however, raise the question of whether or not humans have lost some of their empathy for one another, citing things such as murder and crime against one another as destructive (Izard, 2009).
Joseph LeDoux (1996) focused much of his research on the emotion of fear. He did so by giving the example of becoming fearful of a snake, when the snake is actually a stick. Fear can take two routes in the brain, and based on his dual route model, it is a direct route, or a much less direct route. In regards to evolution the less direct route is the newer one. With a path moving through the neocortex and finally to the amygdala, it is a process that could only happen after the formation of the "new" brain. The faster response (thalamus to amygdala) may make the difference between surviving and passing on genes (LeDoux, 1996).
See also
References
 | This article includes a list of references, related reading, or external links, but its sources remain unclear because it lacks inline citations. (May 2009) |
- Bell, C. (1844). The anatomy and philosophy of expression as connected with the fine arts (3rd ed.). London: John Murray.
- Darwin, C. (2005). The Descent of Man, and Selection in Relation to Sex. Paris: Adamant Media Corporation. (Original work published 1871).
- Darwin, C. (2007). The Expression of the Emotions in Man and Animals. New York: Filiquarian. (Original work published 1872).
- Ekman, P. (1993, April). Facial expression and emotion. American Psychologist, 48(4), 384-392.
- Ekman, P., & Friesen, W. (1969). The repertoire of nonverbal behavior: Categories, origins, usage, and coding. Semiotica , 1, 49-98.
- Ekman, P. & Friesen, W.V. (1971, February). Constants across cultures in the face and emotion. Journal Of Personality And Social Psychology, 17(2), 124-129.
- Hess, U., & Thibault, P. (2009). Darwin and Emotion Expression. American Psychologist, 64(2), 120-128.
- Izard, C. (2009, February). Emotion Theory and Research: Highlights, Unanswered Questions, and Emerging Issues. Annual Review of Psychology, 60(1), 1-25.
- Ledoux, J. (1996). The Emotional Brain: The Mysterious Underpinnings of Emotional Life. New York, NY: Simon & Schuster.