Yawn: Difference between revisions

Yawn
Yawn
	A yawning koala
Organisms	Vertebrates
Biological system	Nervous system
Health	Unaffected or beneficial
Action	Involuntary
Stimuli	Fatigue; Boredom; Stress; Sleepiness; Others mirror neuron reflex;
Method	Complete extension of jaw, inhalation, eyes close, stretching of the eardrum, exhalation
Duration	Usually 6 seconds

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A yawn is a reflex in vertebrate animals characterized by a long inspiratory phase with gradual mouth gaping, followed by a brief climax (or acme) with muscle stretching, and a rapid expiratory phase with muscle relaxation, which typically lasts a few seconds.^[2]^[3] For fish and birds, this is described as gradual mouth gaping, staying open for at least 3 seconds and subsequently a rapid closure of the mouth.^[4] Almost all vertebrate animals, including mammals, birds, reptiles, amphibians, and even fish, experience yawning. The study of yawning is called chasmology.^[5]^[6]^[7]

Yawning (oscitation) most often occurs in adults immediately before and after sleep, during tedious activities and as a result of its contagious quality.^[8] It is commonly associated with tiredness, stress, sleepiness, boredom, or even hunger. In humans, yawning is often triggered by the perception that others are yawning (for example, seeing a person yawning, or talking to someone on the phone who is yawning). This is a typical example of positive feedback.^[9] This "contagious" yawning has also been observed in chimpanzees, dogs, cats, birds, and reptiles and can occur between members of different species.^[10]^[11]^[12] Approximately twenty psychological reasons for yawning have been proposed by scholars but there is little agreement on the primacy of any one.^[8]

During a yawn, muscles around the airway are fully stretched, including chewing and swallowing muscles.^[13] Due to these strong repositioning muscle movements, the airway (lungs and throat) dilates to three or four times its original size.^[14]^[15] The tensor tympani muscle in the middle ear contracts, which creates a rumbling noise perceived as coming from within the head; however, the noise is due to mechanical disturbance of the hearing apparatus and is not generated by the motion of air. Yawning is sometimes accompanied, in humans and other animals, by an instinctive act of stretching several parts of the body including the arms, neck, shoulders and back.

Etymology

The English yawn continues a number of Middle English forms: yanen from Old English ġānian, and yenen, yonen from Old English frequentatives ġinian, ġionian, from a Germanic root *gīn-. The Germanic root has Proto-Indo-European cognates, from a root *g̑hēi-^[16] found also with -n- suffix in Greek χαίνω ('to yawn'), and without the -n- in English gap (compare the figura etymologica in Norse ginnunga-gap), gum ('palate') and gasp (via Old Norse), Latin hiō, hiatus, and Greek chasm, chaos.

The Latin term used in medicine is oscitatio (anglicized as oscitation), from the verb oscito ('to open the mouth'). Pandiculation is the act of yawning and stretching simultaneously.^[17]

Proposed causes

Video of a yawning fetus at 30 weeks of pregnancy^[18]

There are a number of theories that attempt to explain why humans and other animals yawn.^[19]^[20]^[21]

One study states that yawning occurs when one's blood contains increased amounts of carbon dioxide and therefore becomes in need of the influx of oxygen (or expulsion of carbon dioxide) that a yawn can provide.^[19] Yawning may reduce oxygen intake compared to normal respiration;^[22] however, the frequency of yawning is not decreased by providing more oxygen or reducing carbon dioxide in the air.^[23]

Animals subject to predation or other dangers must be ready to physically exert themselves at any given moment. At least one study suggests that yawning, especially psychological "contagious" yawning, may have developed as a way of keeping a group of animals alert.^[24] If an animal is drowsy or bored, it will be less alert than when fully awake and less prepared to spring into action. "Contagious" yawning could be an instinctual signal between group members to stay alert.

Nervousness, which often indicates the perception of an impending need for action, has also been suggested as a cause. Anecdotal evidence suggests that yawning helps increase a person's alertness. Paratroopers have been noted to yawn during the moments before they exit their aircraft^[25] and athletes often yawn just before intense exertions.^{[citation needed]}

Another notion states that yawning is the body's way of controlling brain temperature.^[26]^[27] In 2007, researchers, including a professor of psychology from the SUNY Albany (US), proposed yawning may be a means to keep the brain cool. Mammalian brains operate best within a narrow temperature range. In two experiments, subjects with cold packs attached to their foreheads and subjects asked to breathe strictly nasally exhibited reduced contagious yawning when watching videos of people yawning.^[26]^[28] A similar hypothesis suggests yawning is used for regulation of body temperature. Similarly, Guttmann and Dopart (2011) found that when a subject wearing earplugs yawns, the air moving between the subject's ear and the environment causes a breeze to be heard.^[29] Guttmann and Dopart determined that a yawn causes one of three possible situations to occur: the brain cools down due to an influx or outflux of oxygen; pressure in the brain is reduced by an outflux of oxygen; or the pressure of the brain is increased by an influx of air caused by increased cranial space.

One review hypothesized that yawning's goal is to periodically stretch the muscles of the throat, which may be important for efficient vocalization, swallowing, chewing, and also keeping the airway wide.^[13]

Yawning behavior may be altered as a result of medical issues such as diabetes,^[30] stroke,^[31] or adrenal conditions.^[32] Excessive yawning is seen in immunosuppressed patients such as those with multiple sclerosis.^[33] A professor of clinical and forensic neuropsychology at Bournemouth University has demonstrated that cortisol levels rise during yawning.^[34]^[35]

Social function

With respect to a possible evolutionary advantage, yawning might be a herd instinct.^[36] Theories suggest that the yawn serves to synchronize mood in gregarious animals, similar to howling in a wolf pack. It signals fatigue among members of a group in order to synchronize sleeping patterns and periods.

Research by Garrett Norris (2013) involving monitoring the behaviour of students kept waiting in a reception area indicates a connection (supported by neuro-imaging research) between empathic ability and yawning. "We believe that contagious yawning indicates empathy. It indicates an appreciation of other peoples' behavioral and physiological state," says Norris.^[37]

The yawn reflex has long been observed to be contagious. In 1508, Erasmus wrote, "One man's yawning makes another yawn",^[38] and the French proverbialized the idea to "Un bon bâilleur en fait bâiller sept" ('One good gaper makes seven others gape').^[39] Often, if one person yawns, this may cause another person to "empathetically" yawn.^[22] Observing another person's yawning face (especially their eyes), reading or thinking about yawning, or looking at a yawning picture can cause a person to yawn.^[22]^[40]^[41] The proximate cause for contagious yawning may lie with mirror neurons in the frontal cortex of certain vertebrates, which, upon being exposed to a stimulus from conspecific (same species) and occasionally interspecific organisms, activates the same regions in the brain.^[42] Mirror neurons have been proposed as a driving force for imitation, which lies at the root of much human learning, such as language acquisition. Yawning may be an offshoot of the same imitative impulse.

A 2007 study found that young children with autism spectrum disorders do not increase their yawning frequency after seeing videos of other people yawning, in contrast to neurotypical children. In fact, the autistic children actually yawned less during the videos of yawning than during the control videos.^[43]

The relationship between yawn contagion and empathy is strongly supported by a 2011 behavioural study, conducted by Ivan Norscia and Elisabetta Palagi (University of Pisa, Italy). The study revealed that—among other variables such as nationality, gender, and sensory modality—only social bonding predicted the occurrence, frequency, and latency of yawn contagion.^[44] As with other measures of empathy, the rate of contagion was found to be greatest in response to kin, then friends, then acquaintances, and lastly strangers.^[44] Related individuals (r≥0.25) showed the greatest contagion, in terms of both occurrence of yawning and frequency of yawns.^[44] Strangers and acquaintances showed a longer delay in the yawn response (latency) compared to friends and kin.^[44] Hence, yawn contagion appears to be primarily driven by the emotional closeness between individuals.^[44] The social asymmetry in contagious yawning (with contagious yawning being more frequent between familiar subjects than between strangers) remains when only yawns that are heard, but not seen, are considered. This finding makes it unlikely that visual attentional biases are at the basis of the social asymmetry observed in contagious yawning.^[45]

Two classes of yawning have been observed among primates.^[46] In some cases, the yawn is used as a threat gesture as a way of maintaining order in the primates' social structure.^[47] Specific studies were conducted on chimpanzees^[48] and stumptail macaques.^[49] A group of these animals was shown a video of other members of their own species yawning; both species yawned as well. This helps to partly confirm a yawn's "contagiousness".

The Discovery Channel's show MythBusters also tested this concept. In their small-scale, informal study they concluded that yawning is contagious,^[50] although elsewhere the statistical significance of this finding has been disputed.^[51]

Gordon Gallup, who hypothesizes that yawning may be a means of keeping the brain cool, also hypothesizes that "contagious" yawning may be a survival instinct inherited from our evolutionary past. "During human evolutionary history, when we were subject to predation and attacks by other groups, if everybody yawns in response to seeing someone yawn the whole group becomes much more vigilant and much better at being able to detect danger."^[28]

A study by the University of London has suggested that the "contagiousness" of yawns by a human will pass to dogs. The study observed that 21 of 29 dogs yawned when a stranger yawned in front of them but did not yawn when the stranger only opened his mouth.^[10] Helt and Eigsti (2010) showed that dogs, like humans,^[52] develop a susceptibility to contagious yawning gradually, and that while dogs above seven months 'catch' yawns from humans, younger dogs are immune to contagion.^[53] The study also indicated that nearly half of the dogs responded to the human's yawn by becoming relaxed and sleepy, suggesting that the dogs copied not just the yawn, but also the physical state that yawns typically reflect.

Relation to empathy

In a study involving gelada baboons, yawning was contagious between individuals, especially those that were socially close. This suggests that emotional proximity rather than spatial proximity is an indicator of yawn contagion.^[54]

Evidence for the occurrence of contagious yawning linked to empathy is rare outside of primates. It has been studied in Canidae species, such as the domestic dog and wolf. Domestic dogs have shown the ability to yawn contagiously in response to human yawns. Domestic dogs have demonstrated they are skilled at reading human communication behaviours. This ability makes it difficult to ascertain whether yawn contagion among domestic dogs is deeply rooted in their evolutionary history or is a result of domestication. In a 2014 study, wolves were observed in an effort to answer this question. The results of the study showed that wolves are capable of yawn contagion.^[55] This study also found that the social bond strength between individuals affected the frequency of contagious yawning in wolves, supporting previous research which ties contagious yawning to emotional proximity.

Some evidence for contagious yawning has also been found in budgerigars (Melopsittacus undulatus), a species of social parrots.^[56] This indicates that contagious yawning may have evolved several times in different lineages. In budgerigars, contagious yawning does not seem to be related to social closeness.

In certain neurological and psychiatric disorders, such as schizophrenia and autism, the patient has an impaired ability to infer the mental states of others. In such cases, yawn contagion can be used to evaluate their ability to infer or empathize with others. Autism spectrum disorder (ASD) is a developmental disorder which severely affects social and communicative development, including empathy.^{[citation needed]} The results of various studies have showed a diminished susceptibility to contagious yawn compared to the control group of typically developing children.^[57] Since atypical development of empathy is reported in autism spectrum disorder, results support the claim that contagious yawning and the capacity of empathy share common neural and cognitive mechanisms.^{[citation needed]} Similarly, patients with neurological and psychiatric conditions, such as schizophrenia, have shown an impaired ability to empathize with others. Contagious yawning is one means of evaluating such disorders.^{[citation needed]} The Canadian psychiatrist Heinz Lehmann claimed that increases in yawning could predict recovery in schizophrenia.^[58] The impairment of contagious yawning can provide greater insight into its connection to the underlying causes of empathy.

There is still substantial disagreement in the existing literature about whether or not yawn contagion is related to empathy at all.^[59] Empathy is a notoriously difficult trait to measure, and the literature on the subject is confused, with the same species sometimes displaying a connection between contagious yawning and social closeness, and sometimes apparently not. Different experimenters typically use slightly different measures of empathy, making comparisons between studies difficult, and there may be a publication bias, where studies which find a significant correlation between the two tested variables are more likely to be published than studies which do not.^[59] By revising in critical way the literature for and against yawn contagion as an empathy-related phenomenon, a 2020 review has shown that the social and emotional relevance of the stimulus (based on who the yawner is) can be related to the levels of yawn contagion, as suggested by neurobiological, ethological and psychological findings.^[60] Therefore, the discussion over the issue remains open.

Non-human

Seeing a dog & horse & man yawn, makes me
feel how much all animals are built on one structure.

Charles Darwin, Notebook M (1838), 65

Mammals, birds, and other vertebrates yawn.^[61]

In animals, yawning can serve as a warning signal. Charles Darwin's book, The Expression of the Emotions in Man and Animals, mentions that baboons yawn to threaten their enemies, possibly by displaying large canine teeth.^[62] Similarly, Siamese fighting fish yawn only when they see a conspecific (same species) or their own mirror-image, and their yawn often accompanies aggressive attack.^[63] Guinea pigs also yawn in a display of dominance or anger, displaying their impressive incisor teeth. This is often accompanied by teeth chattering, purring and scent marking.

Adelie penguins employ yawning as part of their courtship ritual. Penguin couples face off and the males engage in what is described as an "ecstatic display", opening their beaks and pointing their faces skyward. This trait has also been seen among emperor penguins. Researchers have been attempting to discover why these two different species share this trait, despite not sharing a habitat. Snakes yawn, both to realign their jaws after a meal and for respiratory reasons, as their trachea can be seen to expand when they do this. Dogs, and occasionally cats, often yawn after seeing people yawn^[10]^[64] and when they feel uncertain.^[65] Dogs demonstrate contagious yawning when exposed to human yawning. Dogs are very adept at reading human communication actions, so it is unclear if this phenomenon is rooted in evolutionary history or a result of domestication.^[66] Fish can also yawn, and they will increase this behavior when experiencing a lack of oxygen.^[67] Socially contagious yawning has been observed in budgerigars,^[56] and anecdotally when tired in other parrot species.^[68]

Culture

Some cultures lend yawning moral or spiritual significance. An open mouth has been associated with letting good immaterial things (such as the soul) escape or letting bad ones (evil spirits) enter, and yawning may have been thought to increase these risks.^[69] Covering the mouth when yawning may have been a way to prevent such transmission.^[69] Exorcists believe yawning can indicate that a demon or possessive spirit is leaving its human host during the course of an exorcism.^[70] Thus, covering one's mouth has been conceived as a protective measure against this.

Yawning has also been described as disrespectful (when done before others) or improper (when done alone). For example, in his commentary on Al-Bukhari's hadith collection, Ibn Hajar, an Islamic theologian, mentions that yawning, in addition to its risks of letting demons enter or take hold of one's body, is unbefitting for humans as it makes them look and sound like dogs by crooking men's upright posture and making them howl:

He [Prophet Muhammad] likened excessive yawning to the howling of dogs to deter people from it and to make it seem repulsive, for when a dog howls, it raises its head and opens its mouth widely, and the yawner resembles it when he yawns too much. This is why the Devil laughs at those who yawn, for he succeeds in playing with them and deforming them.

Superstitions regarding the act of yawning may have arisen from concerns over public health. Polydore Vergil (c. 1470–1555), in his De Rerum Inventoribus, writes that it was customary to make the Sign of the Cross over one's mouth, since "alike deadly plague was sometime in yawning, wherefore men used to fence themselves with the sign of the cross ... which custom we retain at this day."^[71]

Yawning is often perceived as implying boredom, and yawning conspicuously in another's presence has historically been a faux pas. In 1663 Francis Hawkins advised, "In yawning howl not, and thou shouldst abstain as much as thou can to yawn, especially when thou speakest."^[72] George Washington said, "If You Cough, Sneeze, Sigh, or Yawn, do it not Loud but Privately; and Speak not in your Yawning, but put Your handkerchief or Hand before your face and turn aside."^[73] These customary beliefs persist in the modern age. One of Mason Cooley's aphorisms is "A yawn is more disconcerting than a contradiction." A loud yawn may even lead to penalties for contempt of court.^[74]

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^ Madsen, Elainie Alenkær; Perssson, Tomas (2012). "Contagious yawning in domestic dog puppies (Canis lupus familiaris): the effect of ontogeny and emotional closeness on low-level imitation in dogs". Animal Cognition. 16 (2): 233–40. doi:10.1007/s10071-012-0568-9. PMID 23076724. S2CID 18440582.
^ Palagi E.; Leone A.; Mancini G.; Ferrari P. F. (2009). "Contagious yawning in gelada baboons as a possible expression of empathy". Proceedings of the National Academy of Sciences. 106 (46): 19262–19267. Bibcode:2009PNAS..10619262P. doi:10.1073/pnas.0910891106. hdl:11381/2292627. PMC 2780782. PMID 19889980.
^ Romero T.; Ito M.; Saito A.; Hasegawa T. (2014). "Social Modulation of Contagious Yawning in Wolves". PLOS ONE. 9 (8): e105963. Bibcode:2014PLoSO...9j5963R. doi:10.1371/journal.pone.0105963. PMC 4146576. PMID 25162677.
^ ^a ^b Gallup, A; Swartwood, L; Militello, J; Sackett, S (2015). "Experimental evidence of contagious yawning in budgerigars (Melopsittacus undulatus)". Animal Cognition. 18 (5): 1051–8. doi:10.1007/s10071-015-0873-1. PMID 26012708. S2CID 17105459.
^ Helt M. S.; Eigsti I. M.; Snyder P. J.; Fein D. A. (2010). "Contagious yawning in autistic and typical development". Child Development. 81 (5): 1620–1631. doi:10.1111/j.1467-8624.2010.01495.x. PMID 20840244.
^ Provine R. R. (2005). "Yawning: the yawn is primal, unstoppable and contagious, revealing the evolutionary and neural basis of empathy and unconscious behavior". American Scientist. 93: 532–539. doi:10.1511/2005.56.532.
^ ^a ^b Massen, J; Gallup, A (2017). "Why contagious yawning does not (yet) equate to empathy". Neuroscience & Biobehavioral Reviews. 80: 573–585. doi:10.1016/j.neubiorev.2017.07.006. hdl:1887/76849. PMID 28735879.
^ Palagi, Elisabetta; Celeghin, Alessia; Tamietto, Marco; Winkielman, Piotr; Norscia, Ivan (2020). "The neuroethology of spontaneous mimicry and emotional contagion in human and non-human animals". Neuroscience & Biobehavioral Reviews. 111: 149–165. doi:10.1016/j.neubiorev.2020.01.020. hdl:2318/1724362. PMID 31972204. S2CID 210836319. 0149-7634.
^ Smith, E. O. (1999-07-01). "Yawning: An evolutionary perspective". Human Evolution. 14 (3): 191–198. doi:10.1007/BF02440156. S2CID 14876709.
^ Chadwick-Jones, John K. (1998). Developing a social psychology of monkeys and apes. Taylor and Francis. p. 48. ISBN 978-0-86377-820-9. Archived from the original on 2021-09-21. Retrieved 2020-10-21.
^ Baenninger R (1987). "Some comparative aspects of yawning in Betta splendens, Homo sapiens, Pantera leo, and Papio sphinx". Journal of Comparative Psychology. 101 (4): 349–354. doi:10.1037/0735-7036.101.4.349.
^ "Why Do Cats Yawn". CatHealth. Archived from the original on 11 March 2016. Retrieved 10 March 2016.
^ Rugaas, Turid (2005). "Yawning". On Talking Terms With Dogs: Calming Signals. Wenatchee: Dogwise. pp. 25–7. ISBN 978-1-929242-36-8.
^ Romero, Teresa; Ito, Marie; Saito, Atsuko; Hasegawa, Toshikazu (2014). "Social Modulation of Contagious Yawning in Wolves". PLOS ONE. 9 (8): e105963. Bibcode:2014PLoSO...9j5963R. doi:10.1371/journal.pone.0105963. PMC 4146576. PMID 25162677.
^ Hasler, C; Suski, C; Hanson, K; Cooke, S; Tufts, B (2009). "The Influence of Dissolved Oxygen on Winter Habitat Selection by Largemouth Bass: An Integration of Field Biotelemetry Studies and Laboratory Experiments". Physiological and Biochemical Zoology. 82 (2): 143–52. doi:10.1086/591806. hdl:10680/1815. PMID 19199559. S2CID 23493633.
^ "Why Does My Parrot Yawn?". For Birds Only Blog. 2017-10-24. Archived from the original on 24 June 2021. Retrieved 17 June 2021.
^ ^a ^b Walusinski, O. (2004). "Yawning Comparative study of knowledge and beliefs". BMJ. 328 (7445): 328:963.2. doi:10.1136/bmj.328.7445.963-a. PMC 390270.
^ Cruz, Gilbert (16 Mar 2009). "The Story of a Modern-Day Exorcist". Time. Archived from the original on 7 March 2018. Retrieved 25 August 2015.
^ Iona Opie and Moira Tatem, A Dictionary of Superstitions (Oxford: Oxford University Press, 1992), 454.
^ Hawkins, Francis Youth's Behavior, or, Decency in Conversation amongst Men (1663) quoted in Mencken, H.L. A New Dictionary of Quotations on Historical Principles from Ancient and Modern Sources New York: Vintage, 1942^{[page needed]}
^ Washington, George; Conway, Moncure Daniel (1890). George Washington's Rules of civility: traced to their sources and restored. University of California. p. 59. ISBN 9781463506391. Archived from the original on 2021-11-01. Retrieved 2020-10-21.
^ Liu, Caitlin (April 20, 2005). "Sleepy Juror Gets Rude Awakening". Los Angeles Times. Archived from the original on October 21, 2010. Retrieved May 7, 2010.

External links

Yawn article in Scholarpedia.
A Real Yawner: Causes, Concerns and Communications of the Yawn, Mary Bridget Reilly, University of Cincinnati, 23 October 2003

[1] Underwood, Emily (4 October 2016). "The bigger your brain, the longer you yawn". Science. doi:10.1126/science.aah7379.

[2] Barbizet, J (1958). "Yawning". J Neurol Neurosurg Psychiatry. 21 (3): 203–209. doi:10.1136/jnnp.21.3.203. PMC 497319. PMID 13576171.

[3] Provine, RR (1986). "Yawning as a stereotyped action pattern and releasing stimulus". Ethology. 72 (2): 109–122. doi:10.1111/j.1439-0310.1986.tb00611.x.

[4] Baenninger, R (1987). "Some comparative aspects of yawning in Betta splendens, Homo sapiens, Panthera leo, and Papio sphinx". J Comp Psychol. 101 (4): 349. doi:10.1037/0735-7036.101.4.349.

[5] Seuntjens, Wolter (2010). "The Hidden Sexuality of the Yawn and the Future of Chasmology". The Mystery of Yawning in Physiology and Disease. Frontiers of Neurology and Neuroscience. Vol. 28. pp. 55–62. doi:10.1159/000307081. ISBN 978-3-8055-9404-2. PMID 20357463.

[6] Mikami, Akichika (January 2011). "Olivier Walusinski (Ed.): The Mystery of Yawning in Physiology and Disease: Karger, Basel, 2010, 160 pp". Primates. 52 (1): 97–99. doi:10.1007/s10329-010-0222-6. S2CID 16749981.

[7] Teive, Hélio A. G.; Munhoz, Renato P.; Camargo, Carlos Henrique F.; Walusinski, Olivier (July 2018). "Yawning in neurology: a review". Arquivos de Neuro-Psiquiatria. 76 (7): 473–480. doi:10.1590/0004-282X20180057. PMID 30066799. S2CID 51890021.

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[9] Camazine, Deneubourg, Franks, Sneyd, Theraulaz, Bonabeau, Self-Organization in Biological Systems, Princeton University Press, 2003. ISBN 0-691-11624-5, ISBN 0-691-01211-3 (pbk.) p. 18.

[Carpenter-10] Shepherd, Alex J.; Senju, Atsushi; Joly-Mascheroni, Ramiro M. (2008). "Dogs catch human yawns". Biology Letters. 4 (5): 446–8. doi:10.1098/rsbl.2008.0333. PMC 2610100. PMID 18682357.

[11] Madsen, Elanie E.; Persson, Tomas; Sayehli, Susan; Lenninger, Sara; Sonesson, Göran (October 16, 2013). "Chimpanzees Show a Developmental Increase in Susceptibility to Contagious Yawning: A Test of the Effect of Ontogeny and Emotional Closeness on Yawn Contagion". PLOS ONE. 8 (10): e76266. Bibcode:2013PLoSO...876266M. doi:10.1371/journal.pone.0076266. PMC 3797813. PMID 24146848.

[12] "Chimps find human yawn contagious, but is it monkey see, monkey do?". Los Angeles Times. October 16, 2013.

[:4-13] Doelman, Christiaan Jacob; Rijken, Johannes Adriaan (2022-02-05). "Yawning and airway physiology: a scoping review and novel hypothesis". Sleep & Breathing = Schlaf & Atmung. 26 (4): 1561–1572. doi:10.1007/s11325-022-02565-7. PMC 9663362. PMID 35122606. S2CID 246534682.

[14] Baenninger, R. (1997-06-01). "On yawning and its functions". Psychonomic Bulletin & Review. 4 (2): 198–207. doi:10.3758/BF03209394. PMID 21331826. S2CID 18001020.

[15] Barbizet, J. (1958-08-01). "Yawning". Journal of Neurology, Neurosurgery, and Psychiatry. 21 (3): 203–209. doi:10.1136/jnnp.21.3.203. PMC 497319. PMID 13576171.

[16] Pokorny (1959:419-422): "g̑hē- : ghə-, and g̑hēi- 'to gape, yawn'", Pokorny (1959:449): "g̑hēu- : g̑hō(u)- : g̑həu- 'to gape, yawn'"

[pandiculate-17] MedOnline.net Archived 2007-05-02 at the Wayback Machine, "pandiculate"

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[36] Schürmann, Martin; Hesse, Maike D.; Stephan, Klaas E.; Saarela, Miiamaaria; Zilles, Karl; Hari, Riitta; Fink, Gereon R. (2005). "Yearning to yawn: The neural basis of contagious yawning". NeuroImage. 24 (4): 1260–4. doi:10.1016/j.neuroimage.2004.10.022. PMID 15670705. S2CID 6269514. (see also Platek, Steven M.; Mohamed, Feroze B.; Gallup, Gordon G. (2005). "Contagious yawning and the brain". Cognitive Brain Research. 23 (2–3): 448–52. doi:10.1016/j.cogbrainres.2004.11.011. PMID 15820652.)

[37] Seward, Liz (2007-09-10). "Sign of empathy". BBC News. Archived from the original on 2014-03-01. Retrieved 2013-07-20.

[38] Erasmus Adagio Chil. III, cent. iv, No 95 (1508) quoted in Stevenson, Burton ed. (1948) The Macmillan Book of Proverbs, Maxims, and Famous Phrases. New York: Macmillan.

[39] Stevenson, Burton ed. (1948) The Macmillan Book of Proverbs, Maxims, and Famous Phrases. New York: Macmillan.

[40] Provine, Robert R. (2010). "Yawning as a Stereotyped Action Pattern and Releasing Stimulus". Ethology. 72 (2): 109–22. doi:10.1111/j.1439-0310.1986.tb00611.x.

[NPR-41] Krulwich, Robert (September 24, 2007). "The Quest to Design the Perfect Yawn: NPR". NPR. Archived from the original on 2010-01-22. Retrieved 2009-09-01.

[42] Ramachandran, V. S. (2000). "Mirror Neurons and Imitation Learning as the Driving Force Behind 'the Great Leap Forward' in Human Evolution". Edge. Vol. 69. Archived from the original on 2019-03-08. Retrieved 2012-05-15.

[43] Senju, A.; Maeda, M.; Kikuchi, Y.; Hasegawa, T.; Tojo, Y.; Osanai, H. (2007). "Absence of contagious yawning in children with autism spectrum disorder". Biology Letters. 3 (6): 706–8. doi:10.1098/rsbl.2007.0337. PMC 2391210. PMID 17698452.

[norsciapalagi-44] Norscia, Ivan; Palagi, Elisabetta (2011). Rogers, Lesley Joy (ed.). "Yawn Contagion and Empathy in Homo sapiens". PLOS ONE. 6 (12): e28472. Bibcode:2011PLoSO...628472N. doi:10.1371/journal.pone.0028472. PMC 3233580. PMID 22163307.

[45] Norscia, Ivan; Zanoli, Anna; Gamba, Marco; Palagi, Elisabetta (2020). "Auditory Contagious Yawning Is Highest Between Friends and Family Members: Support to the Emotional Bias Hypothesis". Frontiers in Psychology. 11: 442. doi:10.3389/fpsyg.2020.00442. PMC 7147458. PMID 32317997. 1664-1078.

[46] Deputte, Bertrand L. (26 April 2010). "Ethological Study of Yawning in Primates. I. Quantitative Analysis and Study of Causation in Two Species of Old World Monkeys (Cercocebus albigena and Macaca fascicularis)". Ethology. 98 (3–4): 221–245. doi:10.1111/j.1439-0310.1994.tb01073.x.

[social_yawn-47] Laura, Poppick (February 18, 2014). "Baboons Use Yawns to Convey Social Messages". Scientific American.

[48] Anderson, J. R.; Myowa-Yamakoshi, M.; Matsuzawa, T. (2004). "Contagious yawning in chimpanzees". Proceedings of the Royal Society B: Biological Sciences. 271 (Suppl 6): S468–S470. doi:10.1098/rsbl.2004.0224. PMC 1810104. PMID 15801606.

[49] Paukner, A.; Anderson, J. R (2006). "Video-induced yawning in stumptail macaques (Macaca arctoides)". Biology Letters. 2 (1): 36–8. doi:10.1098/rsbl.2005.0411. PMC 1617183. PMID 17148320.

[:2-50] "DSC.discovery.com". Archived from the original on 2010-07-23. Retrieved 2010-06-22.

[51] "Busting the Mythbusters with Statistics: Are Yawns Contagious?". Minitab blog. Minitab. Archived from the original on 3 October 2015. Retrieved 25 August 2015.

[Helt-52] Helt, Molly; Eigsti, Inge-Marie (2010). "Contagious Yawning in Autistic and Typical Development". Child Development. 81 (5): 1620–1631. doi:10.1111/j.1467-8624.2010.01495.x. PMID 20840244.

[Madsen-53] Madsen, Elainie Alenkær; Perssson, Tomas (2012). "Contagious yawning in domestic dog puppies (Canis lupus familiaris): the effect of ontogeny and emotional closeness on low-level imitation in dogs". Animal Cognition. 16 (2): 233–40. doi:10.1007/s10071-012-0568-9. PMID 23076724. S2CID 18440582.

[54] Palagi E.; Leone A.; Mancini G.; Ferrari P. F. (2009). "Contagious yawning in gelada baboons as a possible expression of empathy". Proceedings of the National Academy of Sciences. 106 (46): 19262–19267. Bibcode:2009PNAS..10619262P. doi:10.1073/pnas.0910891106. hdl:11381/2292627. PMC 2780782. PMID 19889980.

[55] Romero T.; Ito M.; Saito A.; Hasegawa T. (2014). "Social Modulation of Contagious Yawning in Wolves". PLOS ONE. 9 (8): e105963. Bibcode:2014PLoSO...9j5963R. doi:10.1371/journal.pone.0105963. PMC 4146576. PMID 25162677.

[j1-56] Gallup, A; Swartwood, L; Militello, J; Sackett, S (2015). "Experimental evidence of contagious yawning in budgerigars (Melopsittacus undulatus)". Animal Cognition. 18 (5): 1051–8. doi:10.1007/s10071-015-0873-1. PMID 26012708. S2CID 17105459.

[57] Helt M. S.; Eigsti I. M.; Snyder P. J.; Fein D. A. (2010). "Contagious yawning in autistic and typical development". Child Development. 81 (5): 1620–1631. doi:10.1111/j.1467-8624.2010.01495.x. PMID 20840244.

[58] Provine R. R. (2005). "Yawning: the yawn is primal, unstoppable and contagious, revealing the evolutionary and neural basis of empathy and unconscious behavior". American Scientist. 93: 532–539. doi:10.1511/2005.56.532.

[Massen-59] Massen, J; Gallup, A (2017). "Why contagious yawning does not (yet) equate to empathy". Neuroscience & Biobehavioral Reviews. 80: 573–585. doi:10.1016/j.neubiorev.2017.07.006. hdl:1887/76849. PMID 28735879.

[60] Palagi, Elisabetta; Celeghin, Alessia; Tamietto, Marco; Winkielman, Piotr; Norscia, Ivan (2020). "The neuroethology of spontaneous mimicry and emotional contagion in human and non-human animals". Neuroscience & Biobehavioral Reviews. 111: 149–165. doi:10.1016/j.neubiorev.2020.01.020. hdl:2318/1724362. PMID 31972204. S2CID 210836319. 0149-7634.

[61] Smith, E. O. (1999-07-01). "Yawning: An evolutionary perspective". Human Evolution. 14 (3): 191–198. doi:10.1007/BF02440156. S2CID 14876709.

[62] Chadwick-Jones, John K. (1998). Developing a social psychology of monkeys and apes. Taylor and Francis. p. 48. ISBN 978-0-86377-820-9. Archived from the original on 2021-09-21. Retrieved 2020-10-21.

[63] Baenninger R (1987). "Some comparative aspects of yawning in Betta splendens, Homo sapiens, Pantera leo, and Papio sphinx". Journal of Comparative Psychology. 101 (4): 349–354. doi:10.1037/0735-7036.101.4.349.

[64] "Why Do Cats Yawn". CatHealth. Archived from the original on 11 March 2016. Retrieved 10 March 2016.

[65] Rugaas, Turid (2005). "Yawning". On Talking Terms With Dogs: Calming Signals. Wenatchee: Dogwise. pp. 25–7. ISBN 978-1-929242-36-8.

[66] Romero, Teresa; Ito, Marie; Saito, Atsuko; Hasegawa, Toshikazu (2014). "Social Modulation of Contagious Yawning in Wolves". PLOS ONE. 9 (8): e105963. Bibcode:2014PLoSO...9j5963R. doi:10.1371/journal.pone.0105963. PMC 4146576. PMID 25162677.

[67] Hasler, C; Suski, C; Hanson, K; Cooke, S; Tufts, B (2009). "The Influence of Dissolved Oxygen on Winter Habitat Selection by Largemouth Bass: An Integration of Field Biotelemetry Studies and Laboratory Experiments". Physiological and Biochemical Zoology. 82 (2): 143–52. doi:10.1086/591806. hdl:10680/1815. PMID 19199559. S2CID 23493633.

[68] "Why Does My Parrot Yawn?". For Birds Only Blog. 2017-10-24. Archived from the original on 24 June 2021. Retrieved 17 June 2021.

[bmj.com-69] Walusinski, O. (2004). "Yawning Comparative study of knowledge and beliefs". BMJ. 328 (7445): 328:963.2. doi:10.1136/bmj.328.7445.963-a. PMC 390270.

[70] Cruz, Gilbert (16 Mar 2009). "The Story of a Modern-Day Exorcist". Time. Archived from the original on 7 March 2018. Retrieved 25 August 2015.

[:3-71] Iona Opie and Moira Tatem, A Dictionary of Superstitions (Oxford: Oxford University Press, 1992), 454.

[72] Hawkins, Francis Youth's Behavior, or, Decency in Conversation amongst Men (1663) quoted in Mencken, H.L. A New Dictionary of Quotations on Historical Principles from Ancient and Modern Sources New York: Vintage, 1942^{[page needed]}

[73] Washington, George; Conway, Moncure Daniel (1890). George Washington's Rules of civility: traced to their sources and restored. University of California. p. 59. ISBN 9781463506391. Archived from the original on 2021-11-01. Retrieved 2020-10-21.

[74] Liu, Caitlin (April 20, 2005). "Sleepy Juror Gets Rude Awakening". Los Angeles Times. Archived from the original on October 21, 2010. Retrieved May 7, 2010.

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@@ Line 1: / Line 1: @@
+{{Short description|Natural reflex}}
-[[Image:DogYawn sm wb.jpg|thumb|right|140px|A [[dog]] yawning]]
+{{for|the album by Bill Ryder-Jones|Yawn (album)}}
+{{Redirect|Yawning|the fish species|Yawning (fish)}}
+{{pp|reason=Persistent [[WP:Disruptive editing|disruptive editing]]|small=yes}}
+{{pp-sock|small=yes}}
+{{Infobox body process
+|name              = Yawn
+|image             = Yawning koala bear (3589381656) (cropped).jpg
+|caption           = A yawning [[koala]]
+|organisms         = [[Vertebrate]]s
+|biological system = [[Nervous system]]
+|health            = Unaffected or beneficial
+|action            = Involuntary
+|stimuli           = {{ubl|[[fatigue (medical)|Fatigue]]|[[Boredom]]|[[stress (biological)|Stress]]|[[Sleepiness]]|Others mirror neuron reflex}}
+|method            = Complete extension of [[jaw]], [[inhalation]], [[Eyelid|eyes close]], stretching of the [[eardrum]], [[exhalation]]
+|outcome           =
+|frequency         =
+|duration          = Usually 6 seconds<ref>{{cite journal |last1=Underwood |first1=Emily |title=The bigger your brain, the longer you yawn |journal=Science |date=4 October 2016 |doi=10.1126/science.aah7379}}</ref>
+|footnote          =
+}}
+A '''yawn''' is a [[reflex]] in [[vertebrate]] animals characterized by a long inspiratory phase with gradual mouth gaping, followed by a brief climax (or acme) with muscle stretching, and a rapid expiratory phase with muscle relaxation, which typically lasts a few seconds.<ref>{{cite journal |last1=Barbizet |first1=J |title=Yawning |journal=J Neurol Neurosurg Psychiatry |date=1958 |volume=21 |issue=3 |pages=203–209|doi=10.1136/jnnp.21.3.203 |pmid=13576171 |pmc=497319 }}</ref><ref>{{cite journal |last1=Provine |first1=RR |title=Yawning as a stereotyped action pattern and releasing stimulus |journal=Ethology |date=1986 |volume=72 |issue=2 |pages=109–122|doi=10.1111/j.1439-0310.1986.tb00611.x }}</ref> For fish and birds, this is described as gradual mouth gaping, staying open for at least 3 seconds and subsequently a rapid closure of the mouth.<ref>{{cite journal |last1=Baenninger |first1=R |title=Some comparative aspects of yawning in Betta splendens, Homo sapiens, Panthera leo, and Papio sphinx |journal=J Comp Psychol |date=1987 |volume=101 |issue=4 |page=349|doi=10.1037/0735-7036.101.4.349 }}</ref> Almost all vertebrate animals, including mammals, birds, reptiles, amphibians, and even fish, experience yawning. The study of yawning is called chasmology.<ref>{{cite book |doi=10.1159/000307081 |chapter=The Hidden Sexuality of the Yawn and the Future of Chasmology |title=The Mystery of Yawning in Physiology and Disease |series=Frontiers of Neurology and Neuroscience |year=2010 |last1=Seuntjens |first1=Wolter |volume=28 |pages=55–62 |pmid=20357463 |isbn=978-3-8055-9404-2 }}</ref><ref>{{cite journal |last1=Mikami |first1=Akichika |title=Olivier Walusinski (Ed.): The Mystery of Yawning in Physiology and Disease: Karger, Basel, 2010, 160 pp |journal=Primates |date=January 2011 |volume=52 |issue=1 |pages=97–99 |doi=10.1007/s10329-010-0222-6 |s2cid=16749981 }}</ref><ref>{{cite journal |last1=Teive |first1=Hélio A. G. |last2=Munhoz |first2=Renato P. |last3=Camargo |first3=Carlos Henrique F. |last4=Walusinski |first4=Olivier |title=Yawning in neurology: a review |journal=Arquivos de Neuro-Psiquiatria |date=July 2018 |volume=76 |issue=7 |pages=473–480 |doi=10.1590/0004-282X20180057 |pmid=30066799 |s2cid=51890021 |doi-access=free }}</ref>
+Yawning ('''oscitation''') most often occurs in adults immediately before and after sleep, during tedious activities and as a result of its contagious quality.<ref name=Anderson>{{cite journal |first1=James R. |last1=Anderson |first2=Pauline |last2=Meno |year=2003 |title=Psychological Influences on Yawning in Children |url=http://cpl.revues.org/index390.html |journal=Current Psychology Letters |volume=2 |issue=11 |access-date=2012-05-15 |archive-date=2013-05-29 |archive-url=https://web.archive.org/web/20130529054530/http://cpl.revues.org/index390.html |url-status=live }}</ref> It is commonly associated with [[fatigue (medical)|tiredness]], [[stress (biology)|stress]], [[somnolence|sleepiness]], [[boredom]], or even hunger. In humans, yawning is often triggered by the perception that others are yawning (for example, seeing a person yawning, or talking to someone on the phone who is yawning). This is a typical example of [[positive feedback]].<ref>Camazine, Deneubourg, Franks, Sneyd, Theraulaz, Bonabeau, ''Self-Organization in Biological Systems'', [[Princeton University Press]], 2003. {{ISBN|0-691-11624-5}}, {{ISBN|0-691-01211-3}} (pbk.) p. 18.</ref> This "contagious" yawning has also been observed in [[Common chimpanzee|chimpanzee]]s, dogs, cats, birds, and reptiles and can occur between members of different species.<ref name="Carpenter">{{cite journal |doi=10.1098/rsbl.2008.0333 |year=2008|last1=Shepherd |first1=Alex J. |last2=Senju |first2=Atsushi |last3=Joly-Mascheroni |first3=Ramiro M. |title=Dogs catch human yawns |journal=Biology Letters |volume=4 |issue=5 |pages=446–8 |pmid=18682357 |pmc=2610100}}</ref><ref>{{cite journal |doi=10.1371/journal.pone.0076266|pmid=24146848 |url= |date=October 16, 2013 |title=Chimpanzees Show a Developmental Increase in Susceptibility to Contagious Yawning: A Test of the Effect of Ontogeny and Emotional Closeness on Yawn Contagion |last1= Madsen |first1=Elanie E. |last2=Persson |first2=Tomas |last3=Sayehli |first3=Susan |last4=Lenninger |first4=Sara |last5=Sonesson |first5=Göran |journal=PLOS ONE|volume=8|issue=10 |pages=e76266 |pmc=3797813|bibcode=2013PLoSO...876266M |doi-access=free }}</ref><ref>{{Cite web|url=https://www.latimes.com/science/sciencenow/la-xpm-2013-oct-16-la-sci-sn-chimp-yawn-humans-20131016-story.html|title=Chimps find human yawn contagious, but is it monkey see, monkey do?|date=October 16, 2013|website=Los Angeles Times}}</ref> Approximately twenty psychological reasons for yawning have been proposed by scholars but there is little agreement on the primacy of any one.<ref name=Anderson/>
-There is a fish called '[[Yawning (fish)| Yawning]]' ([[Melamphaes microps]]).
+During a yawn, muscles around the airway are fully stretched, including chewing and swallowing muscles.<ref name=":4" /> Due to these strong repositioning muscle movements, the airway (lungs and throat) dilates to three or four times its original size.<ref>{{Cite journal |last=Baenninger |first=R. |date=1997-06-01 |title=On yawning and its functions |journal=Psychonomic Bulletin & Review |volume=4 |issue=2 |pages=198–207 |doi=10.3758/BF03209394 |pmid=21331826 |s2cid=18001020 |doi-access=free }}</ref><ref>{{Cite journal |last=Barbizet |first=J. |date=1958-08-01 |title=Yawning |journal=Journal of Neurology, Neurosurgery, and Psychiatry |volume=21 |issue=3 |pages=203–209 |doi=10.1136/jnnp.21.3.203 |pmid=13576171 |pmc=497319 }}</ref> The [[tensor tympani muscle]] in the middle ear contracts, which creates a rumbling noise perceived as coming from within the head; however, the noise is due to mechanical disturbance of the hearing apparatus and is not generated by the motion of air. Yawning is sometimes accompanied, in humans and other animals, by an instinctive act of stretching several parts of the body including the arms, neck, shoulders and back.
-A '''yawn''' is a reflex of deep inhalation and exhalation associated with being tired, with a need to [[sleep]], or from [[boredom]]. The word "yawn" has evolved from the [[Middle English]] word <i>yanen</i>, an alteration of <i>yonen</i>, or <i>yenen</i>, which in turn comes from the [[Old English language|Old English]] <i>geonian</i>. ''Pandiculation'' is the term for the act of stretching and yawning. Yawning is a powerful non-verbal message with several possible meanings, depending on the circumstances:
+==Etymology==
-==Causes of yawning==
+The English ''yawn'' continues a number of [[Middle English]] forms: {{lang|enm|yanen}} from Old English {{lang|ang|ġānian}}, and {{lang|enm|yenen, yonen}} from Old English frequentatives {{lang|ang|ġinian, ġionian}}, from a Germanic root ''*gīn-''. The Germanic root has [[PIE root|Proto-Indo-European]] cognates, from a root ''{{PIE|*g̑hēi-}}''<ref>[[IEW|Pokorny]] (1959:419-422): "g̑hē- : ghə-, and g̑hēi- 'to gape, yawn'", Pokorny (1959:449): "g̑hēu- : g̑hō(u)- : g̑həu- 'to gape, yawn'"</ref> found also with ''-n-'' suffix in Greek {{lang|grc|χαίνω}} ('to yawn'), and without the ''-n-'' in English ''[[:wikt:gap|gap]]'' (compare the ''figura etymologica'' in Norse {{lang|non|[[ginnungagap|ginnunga-gap]]}}), ''[[:wikt:gum|gum]]'' ('palate') and ''[[:wikt:gasp|gasp]]'' (via Old Norse), Latin {{lang|la|hiō, hiatus}}, and Greek {{transliteration|grc|[[chasm]], [[chaos (mythology)|chaos]]}}.
+The Latin term used in medicine is {{lang|la|oscitatio}} (anglicized as ''[[:wikt:oscitation|oscitation]]''), from the verb ''oscito'' ('to open the mouth').
-# An indication of [[tiredness]], [[stress (psychology)|stress]], over-work or [[boredom]].
+''[[wikt:pandiculation#English|Pandiculation]]'' is the act of yawning and stretching simultaneously.<ref name=pandiculate>[http://www.medterms.com/script/main/art.asp?articlekey=4752 MedOnline.net] {{Webarchive|url=https://web.archive.org/web/20070502002255/http://www.medterms.com/script/main/art.asp?articlekey=4752 |date=2007-05-02 }}, "pandiculate"</ref>
-# An action indicating psychological decompression after a state of high alert.
-# A means of expressing powerful [[emotion]]s like [[anger]], rejection or apathy.
-# A sign that one is not breathing deeply, and not receiving enough oxygen through the body.
-A yawn can express strong anti-social messages, and so in some cultures people try to mute or mask them by placing a concealing hand over the yawning mouth.
+==Proposed causes==
-[[Image:Ducreuxyawn.jpg|thumb|left|A [[man]] yawning]]
+[[File:Fetal yawning 4D ultrasound ecografia 4D Dr. Wolfgang Moroder.theora.ogv|thumb|Video of a yawning fetus at 30 weeks of pregnancy<ref>{{cite news|doi=10.1371/journal.pone.0050569.g001 |title=Study on fetal yawning |publisher=Plosone.org |doi-access=free }}</ref>]]
-[[Image:catyawn.jpg|thumb|right|A [[cat]] yawning]]
+There are a number of theories that attempt to explain why humans and other animals yawn.<ref name="MSNBC">{{cite web|url=http://www.nbcnews.com/id/3076713/t/little-mystery-why-do-we-yawn/|archive-url=https://web.archive.org/web/20130417063112/http://www.nbcnews.com/id/3076713/t/little-mystery-why-do-we-yawn|url-status=dead|archive-date=17 April 2013|title=Little mystery: Why do we yawn?|year=2013|publisher=MSNBC Interactive|access-date=16 September 2013}}</ref><ref>{{cite web |last=Chudler |first=Eric H |title=Yawning...and Why Yawns are Contagious |url=http://faculty.washington.edu/chudler/yawning.html |date=July 31, 2007 |publisher=University of Washington |access-date=2009-10-03 |archive-url=https://web.archive.org/web/20060112122510/http://faculty.washington.edu/chudler/yawning.html |archive-date=January 12, 2006}}</ref><ref>{{cite journal|last1=Gupta|first1=S|last2=Mittal|first2=S|title=Yawning and its physiological significance.|journal=International Journal of Applied & Basic Medical Research|date=January 2013|volume=3|issue=1|pages=11–5|pmid=23776833|doi=10.4103/2229-516x.112230|pmc=3678674|doi-access=free}}</ref>
-A long-standing hypothesis is that yawning is caused by an excess of [[carbon dioxide]] and lack of [[oxygen]] in the [[blood]]. The [[brain stem]] detects this and triggers the yawn reflex. The [[mouth]] stretches wide and the [[lungs]] inhale deeply, bringing oxygen into the lungs and hence to the bloodstream. It is almost certain however, that this hypothesis is not correct. One study documented that this effect does not exist ("Yawning" by Robert R. Provine, pages 532-539, American Scientist, November-December 2005, Vol 93, No. 6). http://www.americanscientist.org/template/AssetDetail/assetid/47361. A more recent hypothesis is that yawning is used for [[thermoregulation|regulation of body temperature]]. Another hypothesis is that yawns are caused by the same chemicals (neurotransmitters) in the [[brain]] that affect [[emotion]]s, [[mood]], [[appetite]] and other phenomena.  These chemicals include [[serotonin]], [[dopamine]], [[glutamic acid]] and [[nitric oxide]]. As more of these compounds are activated in the [[brain]], the frequency of yawning increases. Conversely, a greater presence in the brain of [[opiate]] [[neurotransmitter]]s such as [[endorphin]]s, reduces the frequency of yawning. Patients taking the serotonin reuptake inhibitor [[Paroxetine|Paxil]] (Paroxetine HCl) have been observed yawning abnormally often.
+One study states that yawning occurs when one's blood contains increased amounts of carbon dioxide and therefore becomes in need of the influx of oxygen (or expulsion of carbon dioxide) that a yawn can provide.<ref name="MSNBC"/> Yawning may reduce oxygen intake compared to normal respiration;<ref name=Provine2005/> however, the frequency of yawning is not decreased by providing more oxygen or reducing carbon dioxide in the air.<ref>{{cite web |url=http://faculty.washington.edu/chudler/yawning.html |title=Yawning.. and why yawning is contagious |date=31 July 2007 |publisher=University of Washington |access-date=2012-11-16 |archive-date=2006-01-12 |archive-url=https://web.archive.org/web/20060112122510/http://faculty.washington.edu/chudler/yawning.html |url-status=live }}</ref>
-Another theory is that yawning is similar to [[stretching]].  Yawning, like stretching, increases blood pressure and heart rate while also flexing many muscles and joints.  Some have observed that if you try to stifle or prevent a yawn by clenching your jaws shut, the yawn is unsatisfying.  As such, the stretching of jaw and face muscles seems to be necessary for a good yawn.
+Animals subject to predation or other dangers must be ready to physically exert themselves at any given moment. At least one study suggests that yawning, especially psychological "contagious" yawning, may have developed as a way of keeping a group of animals alert.<ref>{{cite web |url=http://www.albany.edu/campusnews/releases_368.htm |title=UAlbany News Release - What's in a Yawn ask UAlbany Researchers |publisher=University at Albany |date=29 June 2007 |access-date=7 December 2013 |archive-date=4 April 2014 |archive-url=https://web.archive.org/web/20140404231613/http://www.albany.edu/campusnews/releases_368.htm |url-status=live }}</ref> If an animal is drowsy or bored, it will be less alert than when fully awake and less prepared to spring into action. "Contagious" yawning could be an instinctual signal between group members to stay alert.
-[[Image:Cockatiel yawning.jpg|thumb|right|A [[cockatiel]] yawning]]
+[[File:Yawning Infant, August 2018.jpg|thumb|left|Research data strongly suggest that neither contagious nor story-induced yawning is reliable in children below the age of six years.<ref name=Anderson/>]]
-The yawn reflex is often described as contagious: if one person yawns, this will cause another person to "sympathetically" yawn.{{ref|emilie}}  The reasons for this are unclear; however, recent research suggests that yawning might be a [[herd instinct]].{{ref|neuroimage}}  Other theories suggest that the yawn serves to synchronize mood behavior among gregarious animals, similar to the howling of the [[wolf]] pack during a [[full moon]]. It signals tiredness to other members of the group in order to synchronize sleeping patterns and periods of activity. It can serve as a warning in displaying large, [[canine teeth]], thus proclaiming, "don't attack while I am sleeping..."  The contagion of yawning is interspecific (i.e., try yawning in front of your dog). Ironically, yawning in public is generally regarded as impolite in the West, but came into fashion in polite French society for a brief period in the late 18th century. Oddly, sometimes sympathetic yawning may be caused by simply looking at a picture of a person or animal yawning, or even seeing the word "yawn".
+Nervousness, which often indicates the perception of an impending need for action, has also been suggested as a cause. Anecdotal evidence suggests that yawning helps increase a person's alertness. Paratroopers have been noted to yawn during the moments before they exit their aircraft<ref name="newscientist">{{cite magazine |url=https://www.newscientist.com/article/mg19426104.400-yawning-may-boost-brains-alertness.html |title=Yawning may boost brain's alertness |last=Hooper |first=Rowan |date=2 July 2007 |magazine=New Scientist |access-date=2009-09-01 |archive-date=2009-04-27 |archive-url=https://web.archive.org/web/20090427221054/http://www.newscientist.com/article/mg19426104.400-yawning-may-boost-brains-alertness.html |url-status=live }}</ref> and athletes often yawn just before intense exertions.{{Citation needed|date=December 2020}}
+Another notion states that yawning is the body's way of controlling brain temperature.<ref name=Gallup2007>{{cite journal |first1=Andrew C. |last1=Gallup |last2=Gallup |title=Yawning as a brain cooling mechanism: Nasal breathing and forehead cooling diminish the incidence of contagious yawning |journal=Evolutionary Psychology |volume=5 |issue=1 |pages=92–101 |date=June 21, 2007 |doi=10.1177/147470490700500109 |doi-access=free }}</ref><ref>{{cite web |url=http://dsc.discovery.com/news/2008/12/15/yawn-brain-head.html |title=Discovery News |access-date=2008-12-15 |archive-date=2008-12-16 |archive-url=https://web.archive.org/web/20081216015403/http://dsc.discovery.com/news/2008/12/15/yawn-brain-head.html |url-status=live }}</ref> In 2007, researchers, including a professor of psychology from the [[SUNY Albany]] (US), proposed yawning may be a means to keep the brain cool. Mammalian brains operate best within a narrow temperature range. In two experiments, subjects with cold packs attached to their foreheads and subjects asked to breathe strictly nasally exhibited reduced contagious yawning when watching videos of people yawning.<ref name=Gallup2007/><ref name=GMA>{{cite video |people=[[Gordon G. Gallup]] |title=Good Morning America&nbsp;– The Science of Yawning (July 30, 2007) |url=https://abcnews.go.com/GMA/Story?id=3425960&page=1 |medium=TV-Series |publisher=ABC |location=USA |date=2007}}</ref>
-[[Adelie Penguin]]s employ yawning as part of their [[courtship]] ritual. Penguin couples face off and the males engage in what is described as an "ecstatic display," their [[beak]]s open wide and their faces pointed skyward.
+A similar hypothesis suggests yawning is used for [[thermoregulation|regulation of body temperature]]. Similarly, Guttmann and Dopart (2011) found that when a subject wearing earplugs yawns, the air moving between the subject's ear and the environment causes a breeze to be heard.<ref>{{cite web |url=http://www.enn.com/health/article/43278/print |title=Global Health and Wellness News: Yawn! |publisher=Enn.com |date=2011-09-20 |access-date=2014-03-02 |archive-date=2014-02-02 |archive-url=https://web.archive.org/web/20140202112349/http://www.enn.com/health/article/43278/print |url-status=live }}</ref> Guttmann and Dopart determined that a yawn causes one of three possible situations to occur: the brain cools down due to an influx or outflux of oxygen; pressure in the brain is reduced by an outflux of oxygen; or the pressure of the brain is increased by an influx of air caused by increased cranial space.
+One review hypothesized that yawning's goal is to periodically stretch the muscles of the throat, which may be important for efficient vocalization, swallowing, chewing, and also keeping the airway wide.<ref name=":4">{{Cite journal |last1=Doelman |first1=Christiaan Jacob |last2=Rijken |first2=Johannes Adriaan |date=2022-02-05 |title=Yawning and airway physiology: a scoping review and novel hypothesis |journal=Sleep & Breathing = Schlaf & Atmung |volume=26 |issue=4 |pages=1561–1572 |doi=10.1007/s11325-022-02565-7 |pmid=35122606 |pmc=9663362 |s2cid=246534682 }}</ref>
-== Yawning in Popular Culture ==
+Yawning behavior may be altered as a result of medical issues such as [[diabetes]],<ref>{{cite journal |doi=10.1152/ajpregu.00429.2006 |title=Lack of central nitric oxide triggers erectile dysfunction in diabetes |year=2006 |last1=Zheng |first1=Hong |last2=Bidasee |first2=Keshore R. |last3=Mayhan |first3=William G. |last4=Patel |first4=Kaushik P. |journal=AJP: Regulatory, Integrative and Comparative Physiology |volume=292 |issue=3 |pmid=17095652 |pages=R1158–64}}</ref> stroke,<ref name=":0">{{cite web|author=Steve Jones |url=https://www.telegraph.co.uk/science/steve-jones/6583820/Yawning-is-part-of-what-makes-us-human.html |archive-url=https://web.archive.org/web/20091120065150/http://www.telegraph.co.uk/science/steve-jones/6583820/Yawning-is-part-of-what-makes-us-human.html |url-status=dead |archive-date=2009-11-20 |title=Telegraph.co.uk |publisher=Telegraph.co.uk |access-date=2013-07-20}}</ref> or [[adrenal gland|adrenal conditions]].<ref>{{cite journal |doi=10.1016/j.bbr.2004.02.013 |title=Adrenalectomy and dexamethasone replacement on yawning behavior |year=2004 |last1=Anías-Calderón |first1=José |last2=Verdugo-Díaz |first2=Leticia |last3=Drucker-Colín |first3=René |journal=Behavioural Brain Research |volume=154 |pages=255–9 |pmid=15302132 |issue=1|s2cid=37006215 }}</ref> Excessive yawning is seen in immunosuppressed patients such as those with multiple sclerosis.<ref>{{cite journal |doi=10.1016/j.msard.2018.04.019 |title=Yawning and cortisol levels in multiple sclerosis: potential new diagnostic tool |year=2018 |last1=Thompson |first1=S.B.N. |last2=Coleman |first2=A. |last3=Williams |first3=N. |journal=Multiple Sclerosis & Related Disorders |volume=23 |pages=51–5 |pmid=29772467 |s2cid=21715886 |url=http://eprints.bournemouth.ac.uk/31829/7/Manuscript.pdf }}</ref> A professor of clinical and forensic neuropsychology at Bournemouth University has demonstrated that cortisol levels rise during yawning.<ref>{{cite journal |doi=10.2196/ijmr.2241 |title=Born to yawn? Understanding yawning as a warning of the rise in cortisol levels: randomized trial |year=2012 |last1=Thompson |first1=S.B.N. |last2=Bishop |first2=P. |journal=Interactive Journal of Medical Research |volume=1 |number=2 |pages=1–9|pmid=23611879 |doi-access=free |pmc=3626133 }}</ref><ref name=":1">{{cite journal|url=http://eprints.bournemouth.ac.uk/22534/1/Cortisol-Frankham-Bishop.pdf |title=The art of capturing a yawn using the science of nerve impulses and cortisol levels in a randomized controlled trial. Thompson Cortisol Hypothesis as a potential predictor of neurological impairment |year=2014 |last1=Thompson |first1=S.B.N. |last2=Frankham |first2=C. |last3=Bishop |first3=P. |journal=Interactive Journal of Arts & Sciences |volume=7 |number=3 |pages=543–57}}</ref>
-Certain [[superstition|superstitions]] surround the act of yawning.  The most common of these is the belief that it is necessary to cover one's mouth when one is yawning in order to prevent one's [[soul]] from escaping the body.  The [[Ancient Greeks]] believed that yawning was not a sign of [[boredom]], but that a person's [[soul]] was trying to escape from its body, so that it may rest with the [[gods]] in the skies.
+==Social function==
-A similar belief holds that yawning is caused by the [[Devil]], who sends evil spirits to enter a person's body when his or her mouth is open.  Thus, covering one's mouth prevents the evil spirits from entering.  It is also why some people close a baby's mouth when it yawns.
+[[File:Edgar Germain Hilaire Degas 084.jpg|thumb|left|''Two women ironing'', one with a yawn, by [[Edgar Degas]]]]
+With respect to a possible evolutionary advantage, yawning might be a [[herd instinct]].<ref>{{cite journal |doi=10.1016/j.neuroimage.2004.10.022 |title=Yearning to yawn: The neural basis of contagious yawning |year=2005 |last1=Schürmann |first1=Martin |last2=Hesse |first2=Maike D. |last3=Stephan |first3=Klaas E. |last4=Saarela |first4=Miiamaaria |last5=Zilles |first5=Karl |last6=Hari |first6=Riitta |last7=Fink |first7=Gereon R. |journal=NeuroImage |volume=24 |issue=4 |pages=1260–4 |pmid=15670705|s2cid=6269514 }} (see also {{cite journal |doi=10.1016/j.cogbrainres.2004.11.011 |title=Contagious yawning and the brain |year=2005 |last1=Platek |first1=Steven M. |last2=Mohamed |first2=Feroze B. |last3=Gallup |first3=Gordon G. |journal=Cognitive Brain Research |volume=23 |issue=2–3 |pages=448–52 |pmid=15820652}})</ref> Theories suggest that the yawn serves to synchronize mood in [[social relation|gregarious]] animals, similar to howling in a [[wolf]] pack. It signals fatigue among members of a group in order to synchronize sleeping patterns and periods.
-Other superstitions include:
+Research by Garrett Norris (2013) involving monitoring the behaviour of students kept waiting in a reception area indicates a connection (supported by neuro-imaging research) between empathic ability and yawning. "We believe that contagious yawning indicates empathy. It indicates an appreciation of other peoples' behavioral and physiological state," says Norris.<ref>{{cite news |last=Seward |first=Liz |url=http://news.bbc.co.uk/2/hi/science/nature/6988155.stm |title=Sign of empathy |work=BBC News |date=2007-09-10 |access-date=2013-07-20 |archive-date=2014-03-01 |archive-url=https://web.archive.org/web/20140301065827/http://news.bbc.co.uk/2/hi/science/nature/6988155.stm |url-status=live }}</ref>
-*A yawn is a sign that danger is near.
-*Counting a person's teeth robs them of one year of life for every tooth counted.  This is why some people cover their mouths when they [[laugh]], smile, or yawn.
-*If two persons are seen to yawn one after the other, it is said that the one who yawned last bears no malice towards the one who yawned first.
+The yawn reflex has long been observed to be contagious. In 1508, [[Erasmus]] wrote, "One man's yawning makes another yawn",<ref>[[Erasmus]] ''Adagio'' Chil. III, cent. iv, No 95 (1508) quoted in Stevenson, Burton ed. (1948) ''The Macmillan Book of Proverbs, Maxims, and Famous Phrases''. New York: Macmillan.</ref> and the French proverbialized the idea to {{lang|fr|"Un bon bâilleur en fait bâiller sept"}} ('One good gaper makes seven others gape').<ref>Stevenson, Burton ed. (1948) ''The Macmillan Book of Proverbs, Maxims, and Famous Phrases''. New York: Macmillan.</ref> Often, if one person yawns, this may cause another person to "empathetically" yawn.<ref name=Provine2005>{{cite journal |doi=10.1511/2005.6.532 |title=Yawning |year=2005 |last1=Provine |first1=Robert |journal=American Scientist |volume=93 |issue=6 |page=532}}</ref> Observing another person's yawning face (especially their eyes), reading or thinking about yawning, or looking at a yawning picture can cause a person to yawn.<ref name="Provine2005" /><ref>{{cite journal |doi=10.1111/j.1439-0310.1986.tb00611.x |title=Yawning as a Stereotyped Action Pattern and Releasing Stimulus |year=2010 |last1=Provine |first1=Robert R. |journal=Ethology |volume=72 |issue=2 |pages=109–22}}</ref><ref name="NPR">{{cite web |url=https://www.npr.org/templates/story/story.php?storyId=14654608 |title=The Quest to Design the Perfect Yawn: NPR |last=Krulwich |first=Robert |date=September 24, 2007 |publisher=NPR |access-date=2009-09-01 |archive-date=2010-01-22 |archive-url=https://web.archive.org/web/20100122151932/http://www.npr.org/templates/story/story.php?storyId=14654608 |url-status=live }}</ref> The [[proximate cause]] for contagious yawning may lie with [[mirror neuron]]s in the [[frontal lobe|frontal cortex]] of certain vertebrates, which, upon being exposed to a stimulus from [[conspecific]] (same species) and occasionally interspecific organisms, activates the same regions in the brain.<ref>{{cite magazine |first1=V. S. |last1=Ramachandran |year=2000 |title=Mirror Neurons and Imitation Learning as the Driving Force Behind 'the Great Leap Forward' in Human Evolution |magazine=Edge |volume=69 |url=http://www.edge.org/3rd_culture/ramachandran/ramachandran_index.html |access-date=2012-05-15 |archive-date=2019-03-08 |archive-url=https://web.archive.org/web/20190308010928/https://www.edge.org/3rd_culture/ramachandran/ramachandran_index.html |url-status=live }}</ref> Mirror neurons have been proposed as a driving force for [[imitation]], which lies at the root of much human learning, such as [[language acquisition]]. Yawning may be an offshoot of the same imitative impulse.
-These superstitions may not only have arisen to prevent people from committing the [[faux pas]] of yawning loudly in another's presence -one of [[Mason Cooley|Mason Cooley's]] [[aphorism|aphorisms]] is "A yawn is more disconcerting than a contradiction"- but may also have arisen from concerns over [[public health]].  [[Polydore Vergil]] (c. 1470-1555), in his ''De Rerum Inventoribus'', writes that it was customary to make the sign of the cross over one's mouth, since "alike deadly [[bubonic plague|plague]] was sometime in yawning, wherefore men used to fence themselves with the sign of the cross...which custom we retain at this day."{{ref|opie}}
+A 2007 study found that young children with [[autism spectrum disorder]]s do not increase their yawning frequency after seeing videos of other people yawning, in contrast to neurotypical children. In fact, the autistic children actually yawned less during the videos of yawning than during the control videos.<ref>{{cite journal |doi=10.1098/rsbl.2007.0337 |title=Absence of contagious yawning in children with autism spectrum disorder |year=2007 |last1=Senju |first1=A. |last2=Maeda |first2=M. |last3=Kikuchi |first3=Y. |last4=Hasegawa |first4=T. |last5=Tojo |first5=Y. |last6=Osanai |first6=H. |journal=Biology Letters |volume=3 |issue=6 |pages=706–8 |pmid=17698452 |pmc=2391210}}</ref>
-Some people hold the superstition that when you yawn, someone just walked over your future grave site or the future grave site of your [[children]].
+[[File:Joseph Ducreux (French - Self-Portrait, Yawning - Google Art Project.jpg|thumb|[[Joseph Ducreux]] pandiculating (both yawning and stretching); self-portrait c. 1783]]
+The relationship between yawn contagion and empathy is strongly supported by a 2011 behavioural study, conducted by Ivan Norscia and Elisabetta Palagi ([[University of Pisa]], Italy). The study revealed that—among other variables such as nationality, gender, and sensory modality—only social bonding predicted the occurrence, frequency, and latency of yawn contagion.<ref name=norsciapalagi>{{cite journal |doi=10.1371/journal.pone.0028472 |title=Yawn Contagion and Empathy in ''Homo sapiens'' |year=2011 |editor1-last=Rogers |editor1-first=Lesley Joy |last1=Norscia |first1=Ivan |last2=Palagi |first2=Elisabetta |journal=PLOS ONE |volume=6 |issue=12 |pages=e28472 |pmid=22163307 |pmc=3233580|bibcode=2011PLoSO...628472N |doi-access=free }}</ref> As with other measures of empathy, the rate of contagion was found to be greatest in response to kin, then friends, then acquaintances, and lastly strangers.<ref name=norsciapalagi/> Related individuals (r≥0.25) showed the greatest contagion, in terms of both occurrence of yawning and frequency of yawns.<ref name=norsciapalagi/> Strangers and acquaintances showed a longer delay in the yawn response (latency) compared to friends and kin.<ref name=norsciapalagi/> Hence, yawn contagion appears to be primarily driven by the emotional closeness between individuals.<ref name=norsciapalagi/> The social asymmetry in contagious yawning (with contagious yawning being more frequent between familiar subjects than between strangers) remains when only yawns that are heard, but not seen, are considered. This finding makes it unlikely that visual attentional biases are at the basis of the social asymmetry observed in contagious yawning.<ref>{{cite journal |doi=10.3389/fpsyg.2020.00442 |title=Auditory Contagious Yawning Is Highest Between Friends and Family Members: Support to the Emotional Bias Hypothesis |year=2020 |last1=Norscia |first1=Ivan |last2=Zanoli |first2=Anna|last3=Gamba |first3=Marco |last4=Palagi |first4=Elisabetta |journal= Frontiers in Psychology |volume=11 |page=442 |pmid=32317997 |pmc=7147458 | id=1664-1078 |doi-access=free }}</ref>
+Two classes of yawning have been observed among [[primate]]s.<ref>{{cite journal |last1=Deputte |first1=Bertrand L. |title=Ethological Study of Yawning in Primates. I. Quantitative Analysis and Study of Causation in Two Species of Old World Monkeys (Cercocebus albigena and Macaca fascicularis) |journal=Ethology |date=26 April 2010 |volume=98 |issue=3–4 |pages=221–245 |doi=10.1111/j.1439-0310.1994.tb01073.x }}</ref> In some cases, the yawn is used as a threat gesture as a way of maintaining order in the primates' social structure.<ref name="social yawn">{{cite web |last1=Laura |first1=Poppick |title=Baboons Use Yawns to Convey Social Messages|date=February 18, 2014 |url=https://www.scientificamerican.com/article/baboons-use-yawns-to-convey-social-messages/ |website=Scientific American}}</ref> Specific studies were conducted on chimpanzees<ref>{{cite journal |doi=10.1098/rsbl.2004.0224 |pmid=15801606 |title=Contagious yawning in chimpanzees |year=2004 |last1=Anderson |first1=J. R. |last2=Myowa-Yamakoshi |first2=M. |last3=Matsuzawa |first3=T. |journal=Proceedings of the Royal Society B: Biological Sciences |volume=271 |issue=Suppl 6 |pages=S468–S470|pmc=1810104 }}</ref> and [[Stump-tailed macaque|stumptail macaques]].<ref>{{cite journal |doi=10.1098/rsbl.2005.0411 |title=Video-induced yawning in stumptail macaques (''Macaca arctoides'') |year=2006 |last1=Paukner |first1=A. |last2=Anderson |first2=J. R |journal=Biology Letters |volume=2 |pages=36–8 |pmid=17148320 |issue=1 |pmc=1617183}}</ref> A group of these animals was shown a video of other members of their own species yawning; both species yawned as well. This helps to partly confirm a yawn's "contagiousness".
-== Notes ==
-# {{note|emilie}}     The website by [http://www.dontyawngame.com/ Émilie] attempts to prove this.
+The [[Discovery Channel]]'s show ''[[MythBusters]]'' also tested this concept. In their small-scale, informal study they concluded that yawning is contagious,<ref name=":2">{{Cite web|url=http://dsc.discovery.com/fansites/mythbusters/episode/episode-tab-06.html|title=DSC.discovery.com|access-date=2010-06-22|archive-date=2010-07-23|archive-url=https://web.archive.org/web/20100723110724/http://dsc.discovery.com/fansites/mythbusters/episode/episode-tab-06.html|url-status=live}}</ref> although elsewhere the statistical significance of this finding has been disputed.<ref>{{cite web|title=Busting the Mythbusters with Statistics: Are Yawns Contagious?|url=http://blog.minitab.com/blog/adventures-in-statistics/busting-the-mythbusters-are-yawns-contagious|website=Minitab blog|publisher=Minitab|access-date=25 August 2015|archive-date=3 October 2015|archive-url=https://web.archive.org/web/20151003025203/http://blog.minitab.com/blog/adventures-in-statistics/busting-the-mythbusters-are-yawns-contagious|url-status=live}}</ref>
-# {{note|neuroimage}} Schürmann et al. Yearning to yawn: the neural basis of contagious yawning. ''NeuroImage'' '''24''' (4), 1260&ndash;1264 (2005). PMID 15670705. (see also Platek et al. (2005). Contagious Yawning and The Brain. Cognitive Brain Research, 23(2-3):448-52. PMID: 15820652)
-# {{note|opie}} Iona Opie and Moira Tatem, ''A Dictionary of Superstitions'' (Oxford: Oxford University Press, 1992), 454.
+Gordon Gallup, who hypothesizes that yawning may be a means of keeping the brain cool, also hypothesizes that "contagious" yawning may be a survival instinct inherited from our evolutionary past. "During human evolutionary history, when we were subject to predation and attacks by other groups, if everybody yawns in response to seeing someone yawn the whole group becomes much more vigilant and much better at being able to detect danger."<ref name=GMA/>
+A study by the [[University of London]] has suggested that the "contagiousness" of yawns by a human will pass to dogs. The study observed that 21 of 29 dogs yawned when a stranger yawned in front of them but did not yawn when the stranger only opened his mouth.<ref name="Carpenter"/>
+Helt and Eigsti (2010) showed that dogs, like humans,<ref name=Helt>{{cite journal |doi=10.1111/j.1467-8624.2010.01495.x|title=Contagious Yawning in Autistic and Typical Development |year=2010 |last1=Helt |first1=Molly |last2=Eigsti |first2=Inge-Marie |journal=Child Development |volume=81 |issue=5 |pages=1620–1631 |pmid=20840244 }}</ref> develop a susceptibility to contagious yawning gradually, and that while dogs above seven months 'catch' yawns from humans, younger dogs are immune to contagion.<ref name=Madsen>{{cite journal |doi=10.1007/s10071-012-0568-9|pmid=23076724|title=Contagious yawning in domestic dog puppies (''Canis lupus familiaris''): the effect of ontogeny and emotional closeness on low-level imitation in dogs|year=2012 |last1=Madsen |first1=Elainie Alenkær |last2=Perssson |first2=Tomas |journal=Animal Cognition |volume=16|issue=2|pages=233–40|s2cid=18440582}}</ref> The study also indicated that nearly half of the dogs responded to the human's yawn by becoming relaxed and sleepy, suggesting that the dogs copied not just the yawn, but also the physical state that yawns typically reflect.
+===Relation to empathy===
+In a study involving [[Gelada|gelada baboons]], yawning was contagious between individuals, especially those that were socially close. This suggests that emotional proximity rather than spatial proximity is an indicator of yawn contagion.<ref>{{cite journal |author1=Palagi E. |author2=Leone A. |author3=Mancini G. |author4=Ferrari P. F. | year = 2009 | title = Contagious yawning in gelada baboons as a possible expression of empathy | journal = Proceedings of the National Academy of Sciences | volume = 106 | issue = 46| pages = 19262–19267 | doi=10.1073/pnas.0910891106 |bibcode=2009PNAS..10619262P | pmid=19889980 | pmc=2780782|hdl=11381/2292627 |doi-access=free }}</ref>
+Evidence for the occurrence of contagious yawning linked to empathy is rare outside of primates. It has been studied in [[Canidae]] species, such as the domestic dog and wolf. Domestic dogs have shown the ability to yawn contagiously in response to human yawns. Domestic dogs have demonstrated they are skilled at reading human communication behaviours. This ability makes it difficult to ascertain whether yawn contagion among domestic dogs is deeply rooted in their evolutionary history or is a result of domestication.
+In a 2014 study, wolves were observed in an effort to answer this question. The results of the study showed that wolves are capable of yawn contagion.<ref>{{cite journal |author1=Romero T. |author2=Ito M. |author3=Saito A. |author4=Hasegawa T. | year = 2014 | title = Social Modulation of Contagious Yawning in Wolves | journal = PLOS ONE | volume = 9 | issue = 8| page = e105963 | doi=10.1371/journal.pone.0105963|pmid=25162677 |pmc=4146576 |bibcode=2014PLoSO...9j5963R |doi-access=free }}</ref> This study also found that the social bond strength between individuals affected the frequency of contagious yawning in wolves, supporting previous research which ties contagious yawning to emotional proximity.
+Some evidence for contagious yawning has also been found in budgerigars (''Melopsittacus undulatus''), a species of social parrots.<ref name=j1>{{cite journal |last1=Gallup |first1=A |last2=Swartwood |first2=L |last3=Militello |first3=J |last4=Sackett |first4=S |title=Experimental evidence of contagious yawning in budgerigars (''Melopsittacus undulatus'') |journal=Animal Cognition |date=2015 |volume=18|issue=5 |pages=1051–8 |doi=10.1007/s10071-015-0873-1 |pmid=26012708 |s2cid=17105459 }}</ref> This indicates that contagious yawning may have evolved several times in different lineages. In budgerigars, contagious yawning does not seem to be related to social closeness.
+In certain neurological and psychiatric disorders, such as schizophrenia and autism, the patient has an impaired ability to infer the mental states of others. In such cases, yawn contagion can be used to evaluate their ability to infer or empathize with others. Autism spectrum disorder (ASD) is a developmental disorder which severely affects social and communicative development, including empathy.{{Citation needed|date=August 2023}} The results of various studies have showed a diminished susceptibility to contagious yawn compared to the control group of typically developing children.<ref>{{cite journal |author1=Helt M. S. |author2=Eigsti I. M. |author3=Snyder P. J. |author4=Fein D. A. | year = 2010 | title = Contagious yawning in autistic and typical development | journal = Child Development | volume = 81 | issue = 5| pages = 1620–1631 | doi=10.1111/j.1467-8624.2010.01495.x | pmid=20840244}}</ref> Since atypical development of empathy is reported in autism spectrum disorder, results support the claim that contagious yawning and the capacity of empathy share common neural and cognitive mechanisms.{{Citation needed|reason=which results?|date=August 2023}} Similarly, patients with neurological and psychiatric conditions, such as schizophrenia, have shown an impaired ability to empathize with others. Contagious yawning is one means of evaluating such disorders.{{Citation needed|date=August 2023}} The Canadian psychiatrist Heinz Lehmann claimed that increases in yawning could predict recovery in schizophrenia.<ref>{{cite journal | author = Provine R. R. | year = 2005 | title = Yawning: the yawn is primal, unstoppable and contagious, revealing the evolutionary and neural basis of empathy and unconscious behavior | journal = American Scientist | volume = 93| pages = 532–539 | doi = 10.1511/2005.56.532 }}</ref> The impairment of contagious yawning can provide greater insight into its connection to the underlying causes of empathy.
+There is still substantial disagreement in the existing literature about whether or not yawn contagion is related to empathy at all.<ref name="Massen">{{cite journal |last1=Massen |first1=J |last2=Gallup |first2=A |title=Why contagious yawning does not (yet) equate to empathy. |journal=Neuroscience & Biobehavioral Reviews |date=2017 |volume=80 |pages=573–585 |doi=10.1016/j.neubiorev.2017.07.006|pmid=28735879 |doi-access=free |hdl=1887/76849 |hdl-access=free }}</ref> Empathy is a notoriously difficult trait to measure, and the literature on the subject is confused, with the same species sometimes displaying a connection between contagious yawning and social closeness, and sometimes apparently not. Different experimenters typically use slightly different measures of empathy, making comparisons between studies difficult, and there may be a publication bias, where studies which find a significant correlation between the two tested variables are more likely to be published than studies which do not.<ref name="Massen"/> By revising in critical way the literature for and against yawn contagion as an empathy-related phenomenon, a 2020 review has shown that the social and emotional relevance of the stimulus (based on who the yawner is) can be related to the levels of yawn contagion, as suggested by neurobiological, ethological and psychological findings.<ref>{{cite journal |doi=10.1016/j.neubiorev.2020.01.020 |title= The neuroethology of spontaneous mimicry and emotional contagion in human and non-human animals |year=2020 |last1=Palagi |first1=Elisabetta |last2=Celeghin |first2=Alessia|last3= Tamietto |first3=Marco |last4=Winkielman |first4=Piotr |last5=Norscia |first5=Ivan|journal= Neuroscience & Biobehavioral Reviews |volume=111 |pages= 149–165 |pmid= 31972204 |hdl= 2318/1724362 |s2cid= 210836319 |url= https://research.tilburguniversity.edu/en/publications/6df2bd63-9c07-4070-96de-fdc039324355 | id=0149-7634 |hdl-access=free }}</ref> Therefore, the discussion over the issue remains open.
+==Non-human==
+{{Quote box
+ |quote   = Seeing a dog & horse & man yawn, makes me<br>feel how much all animals are built on one structure.
+ |align   = right
+ |qalign  = left
+ |author  = [[Charles Darwin]]
+ |source  = ''Notebook M'' (1838), [http://darwin-online.org.uk/content/frameset?pageseq=79&itemID=CUL-DAR125.-&viewtype=side 65]
+ |salign  = right}}
+[[File:Close-up view of the head of a white tiger, yawning with the tongue out.jpg|thumb|A white tiger yawning]]
+Mammals, birds, and other vertebrates yawn.<ref>{{cite journal |last=Smith |first=E. O. |date=1999-07-01 |title=Yawning: An evolutionary perspective |journal=Human Evolution |volume=14 |issue=3 |pages=191–198 |doi=10.1007/BF02440156 |s2cid=14876709 }}</ref>
+In animals, yawning can serve as a warning signal. [[Charles Darwin]]'s book, ''[[The Expression of the Emotions in Man and Animals]]'', mentions that baboons yawn to threaten their enemies, possibly by displaying large [[canine teeth]].<ref>{{Cite book |url=https://books.google.com/books?id=SDiB_dDG8vYC&q=baboon+yawn&pg=PA48 |title=Developing a social psychology of monkeys and apes |first=John K. |last=Chadwick-Jones |publisher=Taylor and Francis |year=1998 |page=48 |isbn=978-0-86377-820-9 |access-date=2020-10-21 |archive-date=2021-09-21 |archive-url=https://web.archive.org/web/20210921091408/https://books.google.com/books?id=SDiB_dDG8vYC&q=baboon+yawn&pg=PA48 |url-status=live }}</ref> Similarly, [[Siamese fighting fish]] yawn only when they see a [[conspecific]] (same species) or their own mirror-image, and their yawn often accompanies aggressive attack.<ref>{{cite journal |title=Some comparative aspects of yawning in ''Betta splendens'', ''Homo sapiens'', ''Pantera leo'', and ''Papio sphinx'' |author=Baenninger R |journal=Journal of Comparative Psychology |year=1987 |volume=101 |issue=4 |pages=349–354 |doi=10.1037/0735-7036.101.4.349}}</ref> [[Guinea pig]]s also yawn in a display of dominance or anger, displaying their impressive incisor teeth. This is often accompanied by teeth chattering, purring and scent marking.
+[[Adelie penguin]]s employ yawning as part of their [[courtship]] ritual. Penguin couples face off and the males engage in what is described as an "ecstatic display", opening their [[beak]]s and pointing their faces skyward. This trait has also been seen among [[emperor penguin]]s. Researchers have been attempting to discover why these two different [[species]] share this trait, despite not sharing a [[habitat]]. Snakes yawn, both to realign their jaws after a meal and for respiratory reasons, as their [[vertebrate trachea|trachea]] can be seen to expand when they do this. Dogs, and occasionally cats, often yawn after seeing people yawn<ref name="Carpenter" /><ref>{{cite web|title=Why Do Cats Yawn|url=http://www.cathealth.com/how-and-why/why-do-cats-yawn|publisher=CatHealth|access-date=10 March 2016|archive-date=11 March 2016|archive-url=https://web.archive.org/web/20160311014322/http://www.cathealth.com/how-and-why/why-do-cats-yawn|url-status=live}}</ref> and when they [[Calming signals|feel uncertain]].<ref>{{cite book |first=Turid |last=Rugaas |year=2005 |chapter=Yawning |chapter-url=https://books.google.com/books?id=tB7tONlHCVQC&pg=PA25 |pages=[https://archive.org/details/ontalkingtermswi0000ruga/page/25 25–7] |title=On Talking Terms With Dogs: Calming Signals |publisher=Dogwise |location=Wenatchee |isbn=978-1-929242-36-8 |url=https://archive.org/details/ontalkingtermswi0000ruga/page/25 }}</ref> Dogs demonstrate contagious yawning when exposed to human yawning. Dogs are very adept at reading human communication actions, so it is unclear if this phenomenon is rooted in evolutionary history or a result of domestication.<ref>{{Cite journal | doi=10.1371/journal.pone.0105963| pmid=25162677| pmc=4146576|title = Social Modulation of Contagious Yawning in Wolves| journal=PLOS ONE| volume=9| issue=8| pages=e105963|year = 2014|last1 = Romero|first1 = Teresa| last2=Ito| first2=Marie| last3=Saito| first3=Atsuko| last4=Hasegawa| first4=Toshikazu| bibcode=2014PLoSO...9j5963R| doi-access=free}}</ref> Fish can also yawn, and they will increase this behavior when experiencing a lack of oxygen.<ref>{{cite journal |last1=Hasler |first1=C |last2=Suski |first2=C |last3=Hanson |first3=K |last4=Cooke |first4=S |last5=Tufts |first5=B |title=The Influence of Dissolved Oxygen on Winter Habitat Selection by Largemouth Bass: An Integration of Field Biotelemetry Studies and Laboratory Experiments |journal=Physiological and Biochemical Zoology|pmid=19199559 |doi=10.1086/591806 |volume=82 |year=2009 |issue=2 |pages=143–52 |hdl=10680/1815 |s2cid=23493633 |hdl-access=free }}</ref> Socially contagious yawning has been observed in budgerigars,<ref name=j1/> and anecdotally when tired in other parrot species.<ref>{{cite web |title=Why Does My Parrot Yawn? |url=https://www.forbirdsonlyny.com/blog/2017/10/24/why-does-my-parrot-yawn |website=For Birds Only Blog |access-date=17 June 2021 |archive-date=24 June 2021 |archive-url=https://web.archive.org/web/20210624200634/https://www.forbirdsonlyny.com/blog/2017/10/24/why-does-my-parrot-yawn |url-status=live|date=2017-10-24 }}</ref>
+==Culture==
+[[File:Oscar Bluhm Ermüdende Konversation crop.jpg|thumb|right|A soldier hides his yawn from his lady companion in this detail from a painting by [[Oscar Bluhm]] titled ''Ermüdende Konversation'', or "Wearisome conversation".]]
+Some cultures lend yawning moral or spiritual significance. An open mouth has been associated with letting good immaterial things (such as the [[soul]]) escape or letting bad ones ([[demon|evil spirits]]) enter, and yawning may have been thought to increase these risks.<ref name="bmj.com">{{cite journal |last= Walusinski |first=O. |title= Yawning Comparative study of knowledge and beliefs |journal= BMJ |volume= 328 |issue= 7445 |year= 2004 |page=328:963.2|doi= 10.1136/bmj.328.7445.963-a |pmc= 390270 }}</ref> Covering the mouth when yawning may have been a way to prevent such transmission.<ref name="bmj.com"/> Exorcists believe yawning can indicate that a demon or possessive spirit is leaving its human host during the course of an exorcism.<ref>{{cite magazine|last1=Cruz|first1=Gilbert|title=The Story of a Modern-Day Exorcist|url=http://content.time.com/time/nation/article/0,8599,1885372,00.html|magazine=Time|access-date=25 August 2015|date=16 Mar 2009|archive-date=7 March 2018|archive-url=https://web.archive.org/web/20180307104155/http://content.time.com/time/nation/article/0,8599,1885372,00.html|url-status=live}}</ref> Thus, covering one's mouth has been conceived as a protective measure against this.
+Yawning has also been described as disrespectful (when done before others) or improper (when done alone). For example, in [[Fath Al-Bari|his commentary]] on [[Al-Bukhari]]'s hadith collection, [[Ibn Hajar al-Asqalani|Ibn Hajar]], an Islamic theologian, mentions that yawning, in addition to its risks of letting demons enter or take hold of one's body, is unbefitting for humans as it makes them look and sound like dogs by crooking men's upright posture and making them howl:
+{{Blockquote|He [Prophet [[Muhammad]]] likened excessive yawning to the howling of dogs to deter people from it and to make it seem repulsive, for when a dog howls, it raises its head and opens its mouth widely, and the yawner resembles it when he yawns too much. This is why the Devil laughs at those who yawn, for he succeeds in playing with them and deforming them.}}
+Superstitions regarding the act of yawning may have arisen from concerns over [[public health]]. [[Polydore Vergil]] ({{circa|1470}}–1555), in his ''De Rerum Inventoribus'', writes that it was customary to make the [[Sign of the Cross]] over one's mouth, since "alike deadly [[bubonic plague|plague]] was sometime in yawning, wherefore men used to fence themselves with the sign of the cross{{nbsp}}... which custom we retain at this day."<ref name=":3">[[Iona and Peter Opie|Iona Opie]] and Moira Tatem, ''A Dictionary of Superstitions'' (Oxford: Oxford University Press, 1992), 454.</ref>
+Yawning is often perceived as implying boredom, and yawning conspicuously in another's presence has historically been a faux pas. In 1663 [[Francis Hawkins]] advised, "In yawning howl not, and thou shouldst abstain as much as thou can to yawn, especially when thou speakest."<ref>[[Francis Hawkins|Hawkins, Francis]] ''Youth's Behavior, or, Decency in Conversation amongst Men'' (1663) quoted in [[H.L. Mencken|Mencken, H.L.]] ''A New Dictionary of Quotations on Historical Principles from Ancient and Modern Sources'' New York: Vintage, 1942{{page needed|date=May 2012}}</ref> [[George Washington]] said, "If You Cough, Sneeze, Sigh, or Yawn, do it not Loud but Privately; and Speak not in your Yawning, but put Your handkerchief or Hand before your face and turn aside."<ref>{{cite book|last1=Washington|first1=George|last2=Conway|first2=Moncure Daniel|title=George Washington's Rules of civility: traced to their sources and restored|page=59|year=1890|publisher=University of California|isbn=9781463506391 |url=https://books.google.com/books?id=_bZEAAAAIAAJ&q=If+You+Cough,+Sneeze,+Sigh,+or+Yawn,+do+it+not+Loud+but+Privately;+and+Speak+not+in+your+Yawning,+but+put+Your+handkercheif+or+Hand+before+your+face+and+turn+aside&pg=PA59|access-date=2020-10-21|archive-date=2021-11-01|archive-url=https://web.archive.org/web/20211101023417/https://books.google.com/books?id=_bZEAAAAIAAJ&q=If+You+Cough%2C+Sneeze%2C+Sigh%2C+or+Yawn%2C+do+it+not+Loud+but+Privately&+and+Speak+not+in+your+Yawning%2C+but+put+Your+handkercheif+or+Hand+before+your+face+and+turn+aside=&pg=PA59|url-status=live}}</ref> These customary beliefs persist in the modern age. One of [[Mason Cooley]]'s [[aphorism]]s is "A yawn is more disconcerting than a contradiction." A loud yawn may even lead to penalties for [[contempt of court]].<ref>{{Cite news |url=http://articles.latimes.com/2005/apr/20/local/me-yawn20 |title=Sleepy Juror Gets Rude Awakening |last=Liu |first=Caitlin |date=April 20, 2005 |work=Los Angeles Times |access-date=May 7, 2010 |archive-date=October 21, 2010 |archive-url=https://web.archive.org/web/20101021020348/http://articles.latimes.com/2005/apr/20/local/me-yawn20 |url-status=live }}</ref>
+{{clear}}
+==References==
+{{Reflist|30em}}
+==Further reading==
+* Provine, Robert R. ''Curious Behavior: Yawning, Laughing, Hiccupping, and Beyond'' (Harvard University Press; 2012) 246 pages; examines the evolutionary context for humans.
 ==External links==
+{{wiktionary|yawn}}
-*[http://www.uc.edu/news/ebriefs/yawn.htm Causes, Concerns and Communications of the Yawn]
+{{Commons category|Yawning}}
-*[http://www.howstuffworks.com/question572.htm "What makes us yawn?"]
-*[http://psychology.drexel.edu/ECNL/ Dr. Steven Platek - Yawn Researcher at Drexel University]
+* [http://www.scholarpedia.org/article/Yawn Yawn] article in [[Scholarpedia]].
+* [http://www.uc.edu/news/ebriefs/yawn.htm A Real Yawner: Causes, Concerns and Communications of the Yawn], Mary Bridget Reilly, [[University of Cincinnati]], 23 October 2003
-*[http://www.animalyawns.com/ Archive of animal yawn pictures]
-*[http://education.guardian.co.uk/higher/research/improbable/story/0,11109,1438356,00.html The hidden sexuality of the human yawn]
-*[http://faculty.washington.edu/chudler/yawning.html Yawns, and why do we yawn?]
-*[http://www.world-science.net/exclusives/050309_yawnfrm.htm From a February issue of the research journal Neuroimage]
-*[http://www.oldsuperstitions.com/general.html Old Superstitions.com]
-*[http://www.straightdope.com/classics/a2_309.html Why are yawns contagious?]
+{{Authority control}}
 [[Category:Sleep]]
+[[Category:Sleep physiology]]
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