Amanda Conway
Professor Kerr
H. English 101
September 15, 2010
The genetic similarity between humans and apes is around 99% (Segelken), varying on the species of ape. The similarities between genetics and social interaction are fascinating, and new research has begun surfacing about correlations between non human primate and human facial expressions. A facial coding system created in recent years, Chimp Facial Action Coding System (ChimpFACS) works by identifying homologies, which are similarities that are usually attributed to common origin (Parr and Waller), between facial expressions in non human primates and humans (Parr and Waller). The importance of facial expressions during social interaction is obvious and scientists are discovering that primates use almost identical facial expressions as humans with the same basic social meaning.
Primates, including humans, primarily use auditory and visual communication during social interaction (Parr and Waller). Facial expressions are a particular type of visual communication. They communicate intentions and emotions, helping others around them predict future behavior. Many facial expressions shared between apes and humans are studied, but one of the most well is the bared-teeth display in comparison to a human smile (Parr and Waller). The bared-teeth display, when used by macaques, mandrills, and chimpanzees- primates most closely related to humans- functions to increase affiliation (Parr and Waller). Affiliation is a psychology term meaning an individual’s need to create bonds with others. This display placates the other individual and shows that no harm or aggression is intended. The bared-teeth display is often used during grooming, sexual solicitation, and reconciliations with other members of the group (Parr and Waller). A chimpanzee is clearly more likely to allow himself to be groomed if the group member approaching is showing this type of expression. Reconciliations, between apes or humans, are more favorable if there is smiling and positive energy as opposed to aggressive expressions and behavior. Likewise, humans use a smile to appease and reassure others. Smiling also increases social bonding and cohesion among peers. Often strangers or people meeting for the first time tend to smile more frequently in order to put the other at ease. This also shows that no aggression is intended. indicates friendliness and agreeableness, qualities which are appealing in others. An example of a situation like this is a job interview It would be uncouth, odd, and off-putting for a person to not show these qualities with a new acquaintance. Thus, the comparison between the bared-teeth display and a human smile, and their effects on social interaction, is a perfect example of what researchers study when searching for homologous expressions.
While the social effects of expressions cannot be examined by ChimpFACS, the physical characteristics can be examined and categorized. Physically, the smile of a chimpanzee and human are strikingly similar. In both, the corners of the lips are retracted which expose the top and bottom teeth. These are physical aspects which ChimpFACS can identify. It is a system that assesses the muscle movements of the face and categorizes the specific expression presented (Marshman). Detailed observation and research of chimpanzees and humans has been done in order to make the system reliable and accurate (Marshman). ChimpFACS can even create 3-D image replicas of chimp expressions since photographing the apes can sometimes be tricky business. In order to test ChimpFACS’ accuracy, chimpanzees were used in experiments where they observed 3-D representations of chimpanzee expressions. They were then asked to match the similar expressions. After the chimps completed the matching, Lisa Parr, the researcher, and her team created variations of the original expressions in order to “[determine] when the chimpanzees were using a single feature or if they needed more than one feature to match the similar expressions.” (Rios) The ability to pinpoint and interpret expressions, which are sometimes only slightly varying, using ChimpFACS may be an essential part in understanding how emotional communication between humans has evolved (Rios).
When trying to prove a theory, especially one as controversial as evolution, it is vital to have as much factual evidence as possible. Similarities between apes and humans is not a new subject, but comparing facial expressions and using new evidence of homologies between apes and humans is a fairly recent development. Basic human facial expressions such as fear, happiness, anger, disgust, and playfulness are widely considered to be universal. Perhaps the reasoning for this is because of man’s evolutionary descent from apes. ChimpFACS is the first step towards proving this theory by standardizing the ability to identify human facial expressions which correspond with other primates.
Works Cited
Parr, Lisa A. and Waller, Bridget M. “Understanding chimpanzee expression: insights into the evolution of communication.” Oxford Journals (20 October 2006). Web. 9 September 2010.
Marshman, Paul. ChimpFACS. Welcome to ChimpFACS. Web. 9 September 2010.
Rios, Emily. “Chimpanzee Facial Expressions are Helping Researches Understand Human Emotional Communication.” Yerkes National Primate Research Center (23 March 2007). Web. 7 September 2010.
Sefelken, Roger. “DNA Analysis reveals striking differences between humans and chimps.” Cornell Chronicle (12 February 2004). Web. 15 September 2010.
