Is Yawning Contagious?

I noticed a headline at the BBC today, “Why is yawning contagious?” While most of us would agree that yawning is contagious, I’ve never seen any research on this front. So the headline got me to wondering, is yawning contagious? Or is this just a myth?

After doing a bit of research, I couldn’t find the hard evidence I was looking for, but a couple of (seemingly legitimate) sources strongly implied that this was the case.

First, in the above mentioned BBC piece, they note that, “about half of adult humans are prone to contagious yawning.” Second, I stumbled upon a reference page by University of Washington neuroscientist Eric Chudler where he explains, “yawns become contagious to people between the first and second years of life.” Also, the Discovery Channel show, “Mythbusters,” confirmed this myth.

One reason I thought yawning might be contagious is environmental factors, like a lack of oxygen in the air. But Chudler cites a study which shows changes in the air do not affect frequency or durations of yawns.

So why do we yawn and why is it contagious? According to the BBC piece, a new theory suggests, “the purpose of yawning is to cool the brain so it operates more efficiently and keeps you awake.”

But that still doesn’t solve this matter of contagiousness. The explanation there may be an evolutionary adaptation developed to keep prehistoric human groups in synch. “When we contagiously yawn we are participating in an ancient, hardwired ritual that evolved to help groups stay alert and detect danger,” explained the BBC.

Another possibility, according to the BBC piece: “contagious yawning might have helped early humans communicate their alertness levels and co-ordinate sleeping times.”

A couple of interesting yawn facts:

• The average yawn is six seconds (Chudler)
  
• Humans begin yawning three months after conception (yes, that means you start
• yawning in the womb) (Chudler)
  
• Chimpanzees are the only other species thought to experience contagious yawning (BBC)