While yawning doesn’t necessarily hint at being tired, it can also be linked to a sign of boredom and regulate brain temperature.
Humans experience the “contagious yawning” phenomenon, but its also been noted in baboons, wolves and even dogs.
But it turns out there is no scientific evidence to prove why we do it, it unconsciously happens. The yawning stops once you notice you are actually yawning! Another study has even linked it to human empathy, determining that higher empathy links to contagious yawning.
The common chain yawn theory was although disproved by journal, Adaptive Human Behavior and Physiology but science is yet to fully discredit if it does actually exist.