Did you just yawn? Do not worry; We already know that it is a very contagious behavior. However, scientists disagree about why we yawn or where this gesture comes from. Charles Darwin himself said in 1838 that “ Seeing the yawn of the dog, the horse and the man, makes me feel that all animals are built on the same structure.”
Well, a team of scientists from the State University of New York in Oneonta (USA) decided to observe the yawns of 29 different mammals through YouTube videos : mice, cats, hedgehogs, walruses, elephants, foxes, as well as human beings and found a pattern. Small-brained animals, with fewer neurons in the cerebral cortex, yawned shorter than large-brained animals and more neurons in the wrinkled outer layer of the brain. Thus, animals with larger and more complex brains had convoluted yawns.
In order of yawning, from highest to lowest, human beings (with about 12,000 million neurons in the cerebral cortex) had the longest average yawn , just over 6 seconds; primates are the mammals that yawn the highest number of times; the elephants – which have a similar number of cortical neurons as humans – also yawned for an average of 6 seconds.
What about mammals with tiny brains? In the case of the mice, the yawns lasted only 1.5 seconds. In conclusion, the researchers point out that yawning has a key physiological effect and that it favors the cooling of our thinking organ , supporting the hypothesis that we yawn, in short, to “refresh” the brain.
The study has been published in the journal Science.
