Almost all the animals that have the backbone yawn. Penguins use this as a call for mating snakes for them to relax their jaws while to digest food, and guinea pigs when they are nervous. So why exactly we the people yawn? And is it really contagious?
You’ve probably started to yawn even as a fetus. Babies begin to yawn in the first 3 months, and although not confirmed, it probably has to do with the normal development of the brain.
Scientists now believe that yawning is a way that “cools” the brain when we are too tired, just as the housing of the computer are cooled by cooler. The brain works best at a certain temperature, and tries to avoid overheating. And why the brain is heated? Fatigue and lack of sleep! That explains why many more yawn when we are asleep.
People, dogs and almost all other animals accept yawning as infection. But not as a physiological reaction, but as empathic. In this great role-playing and mirror neurons.