smile

{{Short description|Conscious or unconscious facial muscular movement conveying happiness or pleasure}}

{{About|the facial expression|other uses|Smile (disambiguation)|and|Smiles (disambiguation)|and|Smilin'}}{{distinguish|Simile}}

File:Leonardo da Vinci 043-mod.jpg, who is known for her smile.]]File:Little_kid_smiling..jpg

A smile is a facial expression formed primarily by flexing the muscles at the sides of the mouth. Some smiles include a contraction of the muscles at the corner of the eyes, an action known as a Duchenne smile.

Among humans, a smile expresses delight, sociability, happiness, joy, or amusement. It is distinct from a similar but usually involuntary expression of anxiety known as a grimace. Although cross-cultural studies have shown that smiling is a means of communication throughout the world,{{cite book |first=Carroll E. |last=Izard |year=1971 |title=The Face of Emotion |location=New York |publisher=Appleton-Century-Croft |isbn=978-0-390-47831-3 }}frown there are large differences among different cultures, religions, and societies, with some using smiles to convey confusion, embarrassment, or awkwardness.

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{{Cite journal |url=https://academic.oup.com/scan/article/1/3/221/2362993 |access-date=2022-05-07 |journal=Social Cognitive and Affective Neuroscience | year=2006 |doi=10.1093/scan/nsl031 |pmc=2555422 |pmid=18985109| last1=Parr | first1=L. A. | last2=Waller | first2=B. M. | title=Understanding chimpanzee facial expression: Insights into the evolution of communication | volume=1 | issue=3 | pages=221–228 }} or to signal submission to more dominant group members. The smile may have evolved differently among species, especially among humans.{{cite web|url=https://gizmodo.com/why-do-we-smile-and-laugh-when-were-terrified-1441046376|title=Why do we smile and laugh when we're terrified?|last=Inglis-Arkell|first=Esther|date=7 October 2013|website=Gizmodo|access-date=7 October 2016}}

Social effects

Smiling seems to have a favorable influence upon others and makes one likable and more approachable.{{cite journal |last=Gladstone |first=G. |title=When you're smiling, does the whole world smile for you? |journal=Australasian Psychiatry |year=2002 |volume=10 |issue= 2|pages=144–146 |doi=10.1046/j.1440-1665.2002.00423.x|s2cid=145551014 |doi-access= }} In the social context, smiling and 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.{{cite journal |last=Haakana |first=M. |title=Laughter and smiling: Notes on co-occurrences |journal=Journal of Pragmatics |year=2010 |volume=42 |issue=6 |pages=1499–1512 |doi=10.1016/j.pragma.2010.01.010 }}

= As reinforcement and manipulation =

The influence of smiling on others is not necessarily benign. It may take the form of positive reinforcement, possibly for an underhand manipulative and abusive purpose.{{Cite book|title=Who's Pulling Your Strings ? How to Break The Cycle of Manipulation |first=Harriet B.|last=Braiker |year=2004 |publisher=McGraw Hill Professional |isbn=978-0-07-144672-3}}

Cultural differences

Researchers have found that smiling is more common in some cultures than other cultures. For example, smiles are more common the U.S. and France than in China or Japan.{{Cite journal |last=Tsai |first=Jeanne L. |last2=Ang |first2=Jen Ying Zhen |last3=Blevins |first3=Elizabeth |last4=Goernandt |first4=Julia |last5=Fung |first5=Helene H. |last6=Jiang |first6=Da |last7=Elliott |first7=Julian |last8=Kölzer |first8=Anna |last9=Uchida |first9=Yukiko |last10=Lee |first10=Yi-Chen |last11=Lin |first11=Yicheng |last12=Zhang |first12=Xiulan |last13=Govindama |first13=Yolande |last14=Haddouk |first14=Lise |date=2016 |title=Leaders' smiles reflect cultural differences in ideal affect |url=https://pmc.ncbi.nlm.nih.gov/articles/PMC4760873/ |journal=Emotion (Washington, D.C.) |volume=16 |issue=2 |pages=183–195 |doi=10.1037/emo0000133 |issn=1931-1516 |pmc=4760873 |pmid=26751631}}{{Cite journal |last=Talhelm |first=Thomas |last2=Oishi |first2=Shigehiro |last3=Zhang |first3=Xuemin |date=2019 |title=Who smiles while alone? Rates of smiling lower in China than U.S. |url=https://doi.apa.org/doi/10.1037/emo0000459 |journal=Emotion |language=en |volume=19 |issue=4 |pages=741–745 |doi=10.1037/emo0000459 |issn=1931-1516}} This pattern has been found in posed photos, such as the smiles of political leaders in official pictures and of students in school ID photos. It has also been found when researchers observed rates of smiling in everyday life.{{Cite journal |last=Oettingen |first=Gabriele |last2=Seligman |first2=Martin E. P. |date=1990 |title=Pessimism and behavioural signs of depression in East versus West Berlin |url=https://onlinelibrary.wiley.com/doi/abs/10.1002/ejsp.2420200303 |journal=European Journal of Social Psychology |language=en |volume=20 |issue=3 |pages=207–220 |doi=10.1002/ejsp.2420200303 |issn=1099-0992}}

While smiling is perceived as a positive emotion most of the time, there are many cultures that perceive smiling as a negative expression and consider it unwelcoming. Too much smiling can be viewed as a sign of shallowness or dishonesty.{{cite web|author=Charles Tidwell |url=http://www.andrews.edu/~tidwell/bsad560/NonVerbal.html |title=Non Verbal Communication |publisher=Andrews.edu |access-date=2014-04-22}} In some parts of Asia, 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 area consider smiling at strangers in public to be unusual and even suspicious behavior,{{cite web|url=http://www.rpi.edu/dept/advising/american_culture/social_skills/nonverbal_communication/reading_exercise.htm |title=Nonverbal Communication |publisher=Rpi.edu |access-date=2014-04-22}} or even a sign of stupidity.{{cite news|url=http://www.bbc.com/future/story/20170407-why-all-smiles-are-not-the-same|title=There are 19 types of smile but only six are for happiness|work=BBC Future|first=Zaria|last=Gorvett|date=10 April 2017}}

Systematic large cross-cultural study on social perception of smiling individuals{{Cite journal|last1=Krys|first1=Kuba|last2=-Melanie Vauclair|first2=C.|last3=Capaldi|first3=Colin A.|last4=Lun|first4=Vivian Miu-Chi|last5=Bond|first5=Michael Harris|last6=Domínguez-Espinosa|first6=Alejandra|last7=Torres|first7=Claudio|last8=Lipp|first8=Ottmar V.|last9=Manickam|first9=L. Sam S.|date=June 2016|title=Be Careful Where You Smile: Culture Shapes Judgments of Intelligence and Honesty of Smiling Individuals|journal=Journal of Nonverbal Behavior|volume=40|issue=2|pages=101–116|doi=10.1007/s10919-015-0226-4|issn=0191-5886|pmc=4840223|pmid=27194817}} 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 telling them to smile. For example, Greg Rickford, a member of the Canadian Parliament, told a female journalist to smile rather than answer the question she had asked.{{Cite journal|last1=Laing|first1=Sarah|date=July 25, 2018|title=Why Do Men Need Women To Smile?|journal=Flare|url=https://www.flare.com/news/greg-rickford-marieke-walsh-smile-women/|access-date=2020-09-22|archive-date=2020-10-01|archive-url=https://web.archive.org/web/20201001165500/https://www.flare.com/news/greg-rickford-marieke-walsh-smile-women/|url-status=dead}} Biological anthropologist Helen Fisher states that, while this could be either caring or controlling behavior, such behavior is unlikely to be welcome.{{Cite journal|last1=May|first1=Ashley|date=March 2017|title=Why you shouldn't tell a woman to smile|journal=USA Today|url=https://www.usatoday.com/story/news/nation-now/2017/03/08/dont-tell-women-to-smile/98906528/|access-date=2020-09-22}}

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|File:Gerrit van Honthorst - Smiling Girl, a Courtesan, Holding an Obscene Image - 63-1954 - Saint Louis Art Museum.jpg|Smiling Girl, a Courtesan, Holding an Obscene Image (1625) by Gerard van Honthorst. Humor has been noted as a source of inspiration for many notable Dutch Golden Age painters.{{cite news|url=https://www.nytimes.com/2017/10/21/arts/humor-17th-century-dutch-art.html|title=Need a Good Laugh? Check Out Some 17th-Century Dutch Art |date=October 21, 2017|last=Siegal|first=Nina|newspaper=The New York Times|access-date=October 20, 2023}}

|File:Madame Vigee-Lebrun and her daughter, Jeanne Lucia (Julie).jpg|In her Self-portrait with her daughter Julie (1786), Élisabeth Vigée Le Brun painted herself smiling. When it was exhibited at the Salon of 1787, the court gossip-sheet {{lang|fr|Mémoires secrets}} commented: "An affectation which artists, art-lovers and persons of taste have been united in condemning, and which finds no precedent among the Ancients, is that in smiling, [Madame Vigée LeBrun] shows her teeth."{{cite book|title=The Great Nation: France from Louis XIV to Napoleon|last=Jones|first=Colin|publisher=Penguin Books|location=London|date=2003|page=364|isbn=9780140130935}}

|File:'Willy' smiling. Mary Dillwyn Col. 1853.jpg|A photograph of a Welsh boy, William Mansel (1838–1866), titled 'Willy', smiling at something off camera. Taken {{circa|1853}}, it is the earliest known photograph of a smile.https://www.library.wales/discover-learn/digital-exhibitions/photographs/early-swansea-photography/welsh-pioneers/|title=Swansea{{Dead link|date=July 2024 |bot=InternetArchiveBot |fix-attempted=yes }} in the nineteenth century, Welsh Pioneers.{{cite web | url=https://diff.wikimedia.org/2015/09/18/first-smile-photobomb-wales/#:~:text=Willy%20is%20looking%20at%20something,1853%2C%20when%20he%20was%2018 | title=The first smile and photobomb ever photographed | date=18 September 2015 }}

|File:"No Lessons Today" - Flora Rankin, by Lewis Carroll (1863).png|Photograph taken by Lewis Carroll titled "No Lessons Today" (1863), depicting a child's feelings when school holidays begin. Carroll later sent the photograph to Charles Darwin for possible use in his publication The Expression of the Emotions in Man and Animals.{{cite book|last1=Wakeling|first1=Edward|title=Lewis Carroll: The Man and his Circle |url=https://books.google.com/books?id=OMLFBQAAQBAJ|year=2014|isbn=978-1780768205|page=164|publisher=I.B. Tauris}}

|File:Eating rice, China - collected by Berthold Laufer.jpg|In the late 19th century and early 20th century, photographs taken in the United Kingdom rarely depicted people smiling, in accordance with the cultural conventions of Victorian and Edwardian society. In contrast, the photograph Eating Rice, China depicts a smiling Chinese man.{{cite web|last1=Edwards|first1=Phil|title=Why people never smiled in old photographs|url=https://www.vox.com/2015/4/8/8365997/smile-old-photographs|website=Vox|date=7 October 2016}}

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Dimples

File:VirgilGriffithFace.jpg smiling.]]

Cheek dimples are formed secondary to a bifid zygomaticus major muscle, whose fascial strands insert into the dermis and cause a dermal tethering effect.{{Cite journal |last1=Lari |first1=A. R. |last2=Panse |first2=Nikhil |date=January 2012 |title=Anatomical basis of dimple creation - A new technique: Our experience of 100 cases |journal=Indian Journal of Plastic Surgery|volume=45 |issue=1 |pages=89–93 |doi=10.4103/0970-0358.96593 |issn=1998-376X |pmc=3385407 |pmid=22754160 |doi-access=free }} Dimples are genetically inherited and are a dominant trait.{{Cite journal |last1=Chalathadka |first1=Mahabaleshwara |last2=Shankar |first2=K Kiruba |last3=Lakshmi |first3=G Vijaya |last4=Nithin |first4=VM |last5=Kulkarni |first5=Sneha |last6=Firdousbano |first6=Mulla |date=2019 |title=Evaluation of Prevalence and Morphology of Dimple among Population of Sullia Taluk |journal=Journal of Cutaneous and Aesthetic Surgery |volume=12 |issue=4 |pages=227–230 |doi=10.4103/JCAS.JCAS_109_19 |issn=0974-2077 |pmc=6967164 |pmid=32001967 |doi-access=free }} Having bilateral dimples (dimples in both cheeks) is the most common form of cheek dimples.{{cite journal|last1=Almaary|first1=Hayaat F.|last2=Scott|first2=Cynthia|last3=Karthik|first3=Ramakrishnan|title=New Landmarks for the Surgical Creation of Dimples Based on Facial Form|journal=The Journal of Clinical and Aesthetic Dermatology|volume=11|issue=5|pages=22–26|pmc=5955629|year=2018|pmid=29785234}} 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. 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 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

File:Smiling girl.jpg

While conducting research on the physiology of facial expressions in the mid-19th century, French neurologist Guillaume Duchenne 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 (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".{{cite book|last1=Davis|first1=Darryl|title=How to Design a Life Worth Smiling About: Developing Success in Business and in Life|publisher=McGraw Hill Professional|isbn=9780071819879|page=8|url=https://books.google.com/books?id=DHbhAgAAQBAJ&pg=PA8|date=2014-05-30}} {{subscription required|s}} An exaggerated Duchenne smile is sometimes associated with lying.{{Cite web|url=https://www.theweek.co.uk/93854/how-facial-software-can-identify-liars|title=How facial software can identify liars|website=The Week UK|date=24 May 2018 }}

Non-Duchenne smile

A non-Duchenne smile involves only the zygomatic major muscle.Duchenne, Guillaume (1990). The Mechanism of Human Facial Expression. New York: Cambridge University Press. Translated by R. Andrew. Originally published as Mecanisme de la Physionomie Humaine in 1862. 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."{{cite journal |last1=Messinger |first1=D. S. |last2=Fogel |first2=A. |last3=Dickson |first3=K. |year=2001 |title=All smiles are positive, but some smiles are more positive than others |journal=Developmental Psychology |volume=37 |issue=5 |pages=642–653 |doi=10.1037/0012-1649.37.5.642 |pmid=11552760 |citeseerx=10.1.1.502.9428 }}

The "Pan Am smile", also known as the "Botox 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, whose flight attendants would always flash every passenger the same perfunctory smile.{{cite news|last=Harlow|first=John|title=The smile that says where you're from|url=http://www.timesonline.co.uk/tol/news/uk/article516707.ece|access-date=18 January 2011|newspaper=The Sunday Times|date=February 20, 2005 |url-status=dead |archive-url=https://web.archive.org/web/20110629135410/http://www.timesonline.co.uk/tol/news/uk/article516707.ece |archive-date= Jun 29, 2011 }} Botox was introduced for cosmetic use in 2002.{{cite news|last=Fischer|first=Andrea|title=FDA approves Botox Cosmetic to improve the appearance of crow's feet lines|url=https://www.fda.gov/newsevents/newsroom/pressannouncements/ucm367662.htm |website=FDA |access-date=3 November 2013|date=11 September 2013 |url-status=dead |archive-url=https://web.archive.org/web/20131108213809/https://www.fda.gov/newsevents/newsroom/pressannouncements/ucm367662.htm |archive-date= Nov 8, 2013 }} Chronic use of Botox injections to deal with eye wrinkles can result in paralysis of the small muscles around the eyes, preventing the appearance of a Duchenne smile.

Other animals

File:Knoxville zoo - chimpanzee teeth.jpg.]]

In other animals, the baring of teeth is often used as a threat or warning display—known as a snarl—or a sign of submission. For chimpanzees, it can also be a sign of fear. However, not all animal displays of teeth convey negative acts or emotions. For example, Barbary macaques demonstrate an open mouth display as a sign of playfulness, which likely has similar roots and purposes as the human smile.{{cite journal | last1 = Preuschoft | first1 = Signe | year = 1992 | title = 'Laughter' and 'Smile' in Barbary Macaques (Macaca Sylvanus) | journal = Ethology | volume = 91 | issue = 3| pages = 220–36 | doi = 10.1111/j.1439-0310.1992.tb00864.x }}