Although scientists still do not agree about the reasons that causes yawning, a new study make with mammals by the State University of New York (USA) concludes that the greater the durantion/legth (What is better?), the greater the size of the brain.

The scientists studied the behavior of 29 different kinds of yawn, including cats, mice, foxes, hedgehogs, walruses, elephants and humans. The pattern discovered led them to argue that animals whose brain is smaller and have fewer number of neurons have faster yawns than bigger animals and consequently have a bigger size brain, as recorded by the journal "Science".