Contagious yawning remains a mystery

The mouth-agape gesture is so quotidian and universal that it seems like it should already have one of those prosaic sidebars in a high school biology textbook. However, scientists have still not fully cracked the relative mystery behind the yawn (notably, some have argued it’s a tool for regulating brain temperature) or figured out why a single occurrence of the phenomenon can ricochet across a crowded room so easily.









