It's something you probably do every day, but oddly, scientists are still not sure why.
Recently, the scientific community is moving towards the idea that yawning is a thermoregulatory behavior that cools the brain, but its true biological function is still unclear. Moreover, scientists are not entirely sure why it is contagious among social animals like humans. A 2005 study published in the Cognitive Brain Research found that networks in your brain responsible for empathy and social skills are activated when you see someone yawning. Researchers have also noticed that chimpanzees can "catch" yawns from humans.
"Copying the expression on the face of others helps us to understand and understand their present state," said Dr. Matthew Campbell of the National Research Center for Primers at Jerseys at Emory University. Therefore, according to one study, the psychopaths are less prone to contagious yawning.
Read more: The trap of someone's yawn is associated with empathy and the psychopaths are often immune