HOW COME? Yawn and the world yawns with you

How come yawns are so contagious? asks Danielle Sinacori, a student from Wantagh.

Monkey see, monkey do? Just watch as someone's head tilts back, mouth drops open, eyes squint, and forehead furrows. Now add that familiar, drawn-out YAAAWNING sound.

Chances are, you'll yawn in response, even if you felt wide-awake a second before. In fact, just reading about yawning - or thinking about it - can trigger a yawn. Thankfully, just thinking about the flu won't cause you to come down with a case. But when it comes to behaviors, yawning is about as contagious as they come.

In the past several years, studies of yawning have come to the conclusion that this familiar (uncontrollable) response is actually a sign of empathy, our capacity to identify with the feelings and actions of others. And we humans aren't the only contagious yawners on the block.

In a study of gelada baboons, researchers found that the monkeys yawned when they saw other individuals yawn, especially if the monkeys were socially close. So if a baboon being groomed by a fellow baboon yawned, the groomer often yawned, too.

And a 2009 study of chimpanzees found that cartoon yawning worked as well as real-life yawns. Researchers showed computer animations of yawning chimps to a group of 24 chimpanzees. While watching the animated yawning, most of the real-life chimps yawned right along with their cartoon counterparts. The chimps seemed to know the animated chimps weren't real, since they didn't react in either a friendly or aggressive way. But the yawning part proved irresistible.

Many dogs apparently yawn when they see a human yawn, too. In a British study published in 2008, researchers visited with 29 dogs in the pets' familiar surroundings. After making eye contact with the dogs and calling them by name, the experimenters yawned realistically. In another part of the test, the experimenters simply opened their mouths wide.

None of the dogs responded to the open-mouth test by yawning. But an astonishing 72 percent of the dogs yawned after watching the testers' realistic yawns. This indicates, the researchers said, that dogs may feel a kind of empathetic connection with human beings, even those they've never met before.

In fact, scientists think that contagious yawning may be one of the earliest examples of empathy and social awareness in some species. While our primitive ancestors may have started with yawning in concert, we humans soon evolved higher levels of empathy - such as identifying with others who are hurt or sad, and feeling distressed ourselves.

But whether you catch a contagious yawn may depend on what part of the yawner's face you happen to see. Studies with people and animals show that making eye contact or at least glancing at a yawner's eyes seems crucial to feeling the urge to yawn yourself. And if you find it impossible to stifle a yawn when thinking about yawning or watching other yawners, pat yourself on the back. Studies indicate that people who find "yawning along" the most irresistible scored highest on other tests of empathy, too.