Nothing to yawn about?
This involuntary reaction, seemingly unique to humans and chimps, is caused by cues ranging from watching someone yawn to thinking about yawning.(1) In fact, up to 50 percent of adult humans, plus 33 percent of adult chimpanzees, emit contagious yawns.(2)
Contagious yawns versus spontaneous yawns
Contagious yawns are not to be confused with spontaneous yawns. Contagious yawns stem from a type of mindfulness and develop over time. Spontaneous yawns derive from biology and start in the womb. Hypotheses accounting for spontaneous yawns include supplying lungs with air that oxygenates the blood; stretching the lungs via inhalation and exhalation to increase feeling awake; and bringing in fresh air to cool the brain. Spontaneous yawns also express aggression, or the threat of it, by the baring of teeth, a vestigial reflex in humans and a vital tool in chimps.(3)
Contagious yawning in humans happens because of the inherent trait of empathy. Scientists discovered in experiments that the prefrontal cortex, the part of the brain associated with personality and social behavior, activates when a person watches another yawn.(4) And numerous studies prove that contagious yawning in humans occurs immediately after people see, hear, or read about someone yawning.(5) What's more, 60 percent of the time witnesses will yawn after another has done so or talked about having done so.(6)
Inversely, subjects in experiments suppress yawns if participants know they are being watched.(7) Empathy only goes so far when self-consciousness is thrown into the mix, I suppose.
Those who don't experience contagious yawns
Someone with an injured prefrontal cortex often cannot empathize with others and, consequently, doesn't tend to yawn contagiously.(8) Autistic people are another subset rarely emitting contagious yawns, in this case because they may have delays in (or lack) language, communication, or socialization skills, therefore inhibiting empathy.(9)
Further, an experiment of more than 100 autistic children ages 1-6 posited that a) humans unconsciously match mechanics and emotions of others, leading to the ability to empathize, but that b) autistic children struggle to mimic others and pick up on social cues and, thus, are unlikely to have contagious yawning. Results of this study confirmed the latter claim. Plus, the more severe the form of autism, the less likely the child is to yawn contagiously.(10)
The importance of contagious yawns
E. 0. Smith, professor emeritus of anthropology at Emory University, argues that the contagious yawn is "poorly understood (in) evolutionary history."(11) And Simon B. N. Thompson, specializing in clinical psychology and neuropsychology at Bournemouth University in the United Kingdom, concludes in a recent review of the literature on contagious yawning that more research is needed to understand the origin, process and effect of this "scientific conundrum."(12)
Perhaps future investigations will uncover more about the relationship between empathy and contagious yawning and the brain. For now, the next time someone tells you to stop yawning, just respond that you can't help it; you're simply built to empathize. And I hope I made you yawn.
For footnotes, go online to www.phikappaphi.org/forum/spring2011.
Catherine C. Shoults (Missouri State University) is pursuing a master's degree in public health, with a concentration in the epidemiology of infectious disease, from Yale University's School of Public Health. She graduated magna cum laude in biology from Missouri State University's Honors College and was one of six students to earn the school's highest award, the Citizen Scholar. Shoults also won a 2009 Award of Excellence from Phi Kappa Phi to help finance her graduate studies. Email her at firstname.lastname@example.org.
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|Title Annotation:||Science and Technology|
|Author:||Shoults, Catherine C.|
|Publication:||Phi Kappa Phi Forum|
|Date:||Mar 22, 2011|
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