Yawning is considered a pretty good indication of being tired or having a case of the doldrums, but there’s really so much more to it. Even fetuses do it, the ability to yawn shows up within 20 weeks after conception. Some have been known to do it as early on as 11 weeks.
Yawning helps keep the brain cool when internal temperatures rise. The body’s impulse is to yawn as the air it brings in offers a bit of relief from the heat number. Too much isn’t always a good thing, excessive yawning can be a sign of much larger physical problems those include the presence of a brain tumor and the possibility that one is having a heart attack.
Yawning can be a sign of empathy, one theory for the contagious aspect of yawns is that people are identifying with one another. It’s believed that the more empathetic a person is the more likely they are to yawn when they see someone else doing it.
It can spread from humans to dogs, studies show that if there’s human yawns a dog is likely to soon after do the same. It turns out dogs like humans gradually become susceptible to yawning triggered by others as they get older because they begin to develop empathy.
Yawning isn’t contagious for all people, those affected by autism or schizophrenia are less likely to yawn when they see someone else doing it. The cause is believed to be confusion about social cues.