You have entered an incorrect email address! Please enter your email address here By Christine Calder, Assistant Clinical Professor of Behavior, College of Veterinary Medicine, Mississippi State University and first published on theconversation.com.You know the feeling. It’s impossible to resist. You just need to yawn.A yawn consists of an extended gaping of the mouth followed by a more rapid closure. In mammals and birds, a long intake of breath and shorter exhale follows the gaping of the mouth, but in other species such as fish, amphibians, and snakes there is no intake of breath.But what’s behind a yawn, why does it occur?In the past, people have had many hypotheses. As far back as 400 B.C., Hippocrates thought yawning removed bad air from the lungs before a fever. In the 17th and 18th century, doctors believed yawning increased oxygen in the blood, blood pressure, heart rate and blood flow itself. More recently, consensus moved toward the idea that yawning cools down the brain, so when ambient conditions and temperature of the brain itself increase, yawning episodes increase.Despite all these theories, the truth is that scientists do not know the true biological function of a yawn.What we do know is that yawning occurs in just about every species. It happens when an animal is tired. It can be used as a threat display in some species. Yawning can occur during times of social conflict and stress, something researchers call a displacement behavior.And that wide-open mouth can be contagious, especially in social species such as humans, chimpanzees, bonobos, macaques, and wolves.Watching someone yawn – heck, even reading about yawns – can lead you to yawn yourself. Why?Research on humans tell us that people who are more empathetic tend to be more susceptible to contagious yawning. When you see someone else yawn, the networks in your brain responsible for empathy and social skills are activated.Yawning happens in many animal species – and seems to pass from one to another. Robert Gramner on Unsplash, CC BYIs yawning contagious for dogs, too? In 2011, U.K. biologists tested for contagious yawning between people and man’s best friend. Although 5 of the 19 dogs they studied did yawn in response to an unfamiliar person’s yawn, the researchers couldn’t prove the yawns were contagious.In 2013, cognitive and behavioral scientists at the University of Tokyo once again tested contagious yawning in canines while controlling for stress. This time the researchers found that dogs were more likely to yawn in response to a familiar person. They concluded that dogs can “catch” a yawn from humans and that yawning is a social rather than a stress-based behavior.In 2014, University of Nebraska psychologists looked at contagious yawning in shelter dogs. They found that some dogs that yawned when exposed to human yawning had elevated cortisol levels – a proxy for stress. Levels of the cortisol stress hormone did not rise in dogs that didn’t yawn in response to a human yawn. This finding suggests some dogs find human yawning stressful and others do not. More research is needed to evaluate this aspect of the human-dog relationship.So the jury’s still out on the true why of yawning. But when it comes to inter-species yawning, you can collect your own anecdotal data. Try an experiment at home: Yawn and see if your pet yawns back. TAGStheconversation.com Previous articleBare bones Apopka budget may need millage rate increase or red light camera revenue to balanceNext articleWhen caring hurts: Attrition among social workers, medicine’s unsung heroes Denise Connell RELATED ARTICLESMORE FROM AUTHOR Reply Looking at the baby and the dog yawning in the above photos, that is my reaction when I listen to campaign promises from politicians…… The Anatomy of Fear Support conservation and fish with NEW Florida specialty license plate Mama Mia Free webinar for job seekers on best interview answers, hosted by Goodwill June 11 LEAVE A REPLY Cancel reply July 7, 2018 at 5:17 am 1 COMMENT Please enter your name here Please enter your comment! Share on Facebook Tweet on Twitter Save my name, email, and website in this browser for the next time I comment.