A smile is a facial expression formed primarily by flexing the
muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...
s at the sides of the
mouth
In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on ...
. Some smiles include a contraction of the muscles at the corner of the
eyes
Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conve ...
, an action known as a Duchenne smile.
Among
human
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
s, a smile expresses
delight,
sociability
Social behavior is behavior among two or more organisms within the same species, and encompasses any behavior in which one member affects the other. This is due to an interaction among those members. Social behavior can be seen as similar to an ...
,
happiness
Happiness, in the context of Mental health, mental or emotional states, is positive or Pleasure, pleasant emotions ranging from contentment to intense joy. Other forms include life satisfaction, well-being, subjective well-being, flourishin ...
,
joy
The word joy refers to the emotion evoked by well-being, success, or good fortune, and is typically associated with feelings of intense, long lasting happiness.
Dictionary definitions
Dictionary definitions of joy typically include a sense of ...
, or
amusement
Amusement is the state of experiencing humorous and entertaining events or situations while the person or animal actively maintains the experience, and is associated with enjoyment, happiness, laughter and pleasure. It is an emotion with posi ...
. It is distinct from a similar but usually involuntary expression of
anxiety
Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...
known as a
grimace. Although cross-cultural studies have shown that smiling is a means of communication throughout the world, there are large differences among different cultures, religions, and societies, with some using smiles to convey confusion or embarrassment.
Evolutionary background
Primatologist Signe Preuschoft traces the smile back over 30 million years of evolution to a "fear grin" stemming from monkeys and apes, who often used barely clenched teeth to portray to predators that they were harmless or to signal submission to more dominant group members. The smile may have evolved differently among species, especially among humans.
Social effects
Smiling seems to have a favorable
influence
Influence or influencer may refer to:
*Social influence, in social psychology, influence in interpersonal relationships
**Minority influence, when the minority affect the behavior or beliefs of the majority
*Influencer marketing, through individu ...
upon others and makes one ''likable'' and more ''approachable''. In the social context, smiling and
laughter
Laughter is a pleasant physical reaction and emotion consisting usually of rhythmical, often audible contractions of the diaphragm and other parts of the respiratory system. It is a response to certain external or internal stimuli. Laughter ...
have different functions in the order of sequence in social situations:
* Smiling is sometimes a pre-laughing device and is a common pattern for paving the way to laughter;
* Smiling can be used as a response to laughter.
Smiling is a signaling system that evolved from a need to communicate information in many different forms. One of these is an advertisement of sexual interest. Female smiles are appealing to heterosexual males, increasing physical attractiveness and enhancing
sex appeal
Sex is the trait that determines whether a sexually reproducing animal or plant produces male or female gametes. Male plants and animals produce smaller mobile gametes (spermatozoa, sperm, pollen), while females produce larger ones (ova, o ...
. However, recent research indicates a man's smile may or may not be most effective in attracting heterosexual women, and that facial expressions such as pride or even shame might be more effective. The researchers did not explicitly study the role of smiles in other sexual preferences.
As reinforcement and manipulation
The influence of smiling on others is not necessarily benign. It may take the form of
positive reinforcement
In behavioral psychology, reinforcement is a consequence applied that will strengthen an organism's future behavior whenever that behavior is preceded by a specific antecedent stimulus. This strengthening effect may be measured as a higher freq ...
, possibly for an underhand
manipulative and
abusive purpose.
Cultural differences
While smiling is perceived as a positive
emotion
Emotions are mental states brought on by neurophysiological changes, variously associated with thoughts, feelings, behavioral responses, and a degree of pleasure or displeasure. There is currently no scientific consensus on a definition. ...
most of the time, there are many
cultures
Culture () is an umbrella term which encompasses the social behavior, institutions, and norms found in human societies, as well as the knowledge, beliefs, arts, laws, customs, capabilities, and habits of the individuals in these groups.Tyl ...
that perceive smiling as a negative expression and consider it unwelcoming. Too much smiling can be viewed as a sign of shallowness or
dishonesty
Dishonesty is to act without honesty. It is used to describe a lack of probity, cheating, lying, or deliberately withholding information, or being deliberately deceptive or a lack in integrity, knavishness, perfidiosity, corruption or treacherousne ...
. In some parts of
Asia
Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
, people may smile when they are embarrassed or in emotional pain. Some people may smile at others to indicate a friendly greeting. A smile may be reserved for close friends and family members. Many people in the
former Soviet Union
The post-Soviet states, also known as the former Soviet Union (FSU), the former Soviet Republics and in Russia as the near abroad (russian: links=no, ближнее зарубежье, blizhneye zarubezhye), are the 15 sovereign states that wer ...
area consider smiling at strangers in public to be unusual and even suspicious behavior, or even a sign of stupidity.
Systematic large cross-cultural study on social perception of smiling individuals documented that in some cultures a smiling individual may be perceived as less intelligent than the same non-smiling individual (and that cultural uncertainty avoidance may explain these differences). Furthermore, the same study showed that corruption at the societal level may undermine the prosocial perception of smiling—in societies with high corruption indicators, trust toward smiling individuals is reduced.
There can also be gender differences. In the United States and Canada, women report men's telling them to smile. For example,
Greg Rickford
Greg Rickford (born September 24, 1967) is a Canadian politician. He is the Minister of Northern Development and Minister of Indigenous Affairs in the Executive Council of Ontario under Premier Doug Ford. He represents the Kenora-Rainy River r ...
, a member of the Canadian Parliament told a female journalist to smile rather than answer the question she had asked. Biological anthropologist
Helen Fisher states that, while this could be either caring or controlling behavior, such behavior is unlikely to be welcome.
Dimples
Cheek dimples are formed secondary to a bifid
zygomaticus major
The zygomaticus major muscle is a muscle of the human body. It extends from each zygomatic arch (cheekbone) to the corners of the mouth. It is a muscle of facial expression which draws the angle of the mouth superiorly and posteriorly to allow one ...
muscle, whose fascial strands insert into the dermis and cause a dermal tethering effect. Dimples are genetically inherited and are a dominant trait. Having bilateral dimples (dimples in both cheeks) is the most common form of cheek dimples.
A rarer form is the single dimple, which occurs on one side of the face only.
This bifid variation of the muscle originates as a single structure from the
zygomatic bone
In the human skull, the zygomatic bone (from grc, ζῠγόν, zugón, yoke), also called cheekbone or malar bone, is a paired irregular bone which articulates with the maxilla, the temporal bone, the sphenoid bone and the frontal bone. It is si ...
. As it travels anteriorly, it then divides with a superior bundle that inserts in the typical position above the corner of the mouth. An inferior bundle inserts below the corner of the mouth. Dimples are
analogous
Analogy (from Greek ''analogia'', "proportion", from ''ana-'' "upon, according to" lso "against", "anew"+ ''logos'' "ratio" lso "word, speech, reckoning" is a cognitive process of transferring information or meaning from a particular subject ( ...
and how they form in cheeks varies from person to person. The shape of a person's face can affect the look and form as well:
leptoprosopic (long and narrow) faces have long and narrow dimples, and eryprosopic (short and broad) faces have short, circular dimples.
People with a mesoprosopic face are more likely to have dimples in their cheeks than any other face shape.
Duchenne smile
While conducting research on the
physiology
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
of facial expressions in the mid-19th century, French neurologist
Guillaume Duchenne
Guillaume-Benjamin-Amand Duchenne (de Boulogne) (September 17, 1806 in Boulogne-sur-Mer – September 15, 1875 in Paris) was a French neurologist who revived Galvani's research and greatly advanced the science of electrophysiology. The era of mo ...
identified two distinct types of smiles. A Duchenne smile involves contraction of both the
zygomatic major muscle (which raises the corners of the mouth) and the
orbicularis oculi muscle
The orbicularis oculi is a muscle in the face that closes the eyelids. It arises from the nasal part of the frontal bone, from the frontal process of the maxilla in front of the lacrimal groove, and from the anterior surface and borders of a short ...
(which raises the cheeks and forms
crow's feet around the eyes). The Duchenne smile has been described as "smizing", as in "smiling with the eyes". An exaggerated Duchenne smile is sometimes associated with lying.
Non-Duchenne smile
A non-Duchenne smile involves only the zygomatic major muscle. According to Messenger ''et. al.'' "Research with adults initially indicated that joy was indexed by generic smiling, any smiling involving the raising of the lip corners by the zygomatic major .... More recent research suggests that smiling in which the muscle around the eye contracts, raising the cheeks high (Duchenne smiling), is uniquely associated with positive emotion."
The "Pan Am smile", also known as the "
Botox
Botulinum toxin, or botulinum neurotoxin (BoNT), is a neurotoxic protein produced by the bacterium ''Clostridium botulinum'' and related species. It prevents the release of the neurotransmitter acetylcholine from axon endings at the neurom ...
smile", is the name given to a fake smile, in which only the zygomatic major muscle is voluntarily contracted to show politeness. It is named after the now-defunct airline
Pan American World Airways
Pan American World Airways, originally founded as Pan American Airways and commonly known as Pan Am, was an American airline that was the principal and largest international air carrier and unofficial overseas flag carrier of the United States ...
, whose flight attendants would always flash every passenger the same perfunctory smile.
Botox was introduced for cosmetic use in 2002.
Chronic use of Botox injections to deal with eye wrinkle can result in the paralysis of the small muscles around the eyes, preventing the appearance of a Duchenne smile.
In animals
In animals, the baring of teeth is often used as a
threat or warning display—known as a
snarl
A snarl is a sound, often a growl or vicious utterance, often accompanied by a facial expression, where the upper lip is raised, and the nostrils widen, generally indicating hate, anger or pain. In addition to humans, other mammals including m ...
—or a sign of
submission
Deference (also called submission or passivity) is the condition of submitting to the espoused, legitimate influence of one's superior or superiors. Deference implies a yielding or submitting to the judgment of a recognized superior, out of re ...
. For
chimpanzees
The chimpanzee (''Pan troglodytes''), also known as simply the chimp, is a species of great ape native to the forest and savannah of tropical Africa. It has four confirmed subspecies and a fifth proposed subspecies. When its close relative the ...
, it can also be a sign of
fear
Fear is an intensely unpleasant emotion in response to perceiving or recognizing a danger or threat. Fear causes physiological changes that may produce behavioral reactions such as mounting an aggressive response or fleeing the threat. Fear ...
. However, not all animal displays of teeth convey negative acts or emotions. For example,
Barbary macaque
The Barbary macaque (''Macaca sylvanus''), also known as Barbary ape, is a macaque species native to the Atlas Mountains of Algeria, Libya, Tunisia and Morocco, along with a small introduced population in Gibraltar.
It is the type species of the ...
s demonstrate an open mouth display as a sign of playfulness, which likely has similar roots and purposes as the human smile.
See also
*
Facial Action Coding System
The Facial Action Coding System (FACS) is a system to taxonomize human facial movements by their appearance on the face, based on a system originally developed by a Swedish anatomist named Carl-Herman Hjortsjö. It was later adopted by Paul Ek ...
*
Facial expression
A facial expression is one or more motions or positions of the muscles beneath the skin of the face. According to one set of controversial theories, these movements convey the emotional state of an individual to observers. Facial expressions are a ...
*
Frown
A frown (also known as a scowl) is a facial expression in which the eyebrows are brought together, and the forehead is wrinkled, usually indicating displeasure, sadness or worry, or less often confusion or concentration.
The appearance of a fr ...
*
Praise
Praise as a form of social interaction expresses recognition, reassurance or admiration.
Praise is expressed verbally as well as by body language (facial expression and gestures).
Verbal praise consists of a positive evaluations of another's a ...
*
Say cheese
"Say 'cheese is an English-language instruction used by photographers who want their subject or subjects to smile. By saying "cheese", most people form their mouths into what appears to be a smile-like shape.
History
In the late 19th century, d ...
*
Smiley
A smiley, sometimes referred to as a smiley face, is a basic ideogram that represents a smiling face. Since the 1950s it has become part of popular culture worldwide, used either as a standalone ideogram, or as a form of communication, such a ...
References
Further reading
*
* Ottenheimer, H.J. (2006). ''The anthropology of language: An introduction to linguistic anthropology.'' Belmont, CA: Thomson Wadsworh.
* Cited in: Russell and Fernandez-Dols, eds. (1997).
* Russell and Fernandez-Dols, eds. (1997). ''The Psychology of Facial Expression''. Cambridge. .
External links
BBC News: Scanner shows unborn babies smile
{{Authority control
Facial expressions
Laughter
Mouth
Happiness
Social influence