“contagious” yawning in NYC
Definition The involuntary en masse opening of mouths in response to slowed breathing, as occurs with boredom, exhaustion or sedentary activity. By opening the mouth wide and inhaling deeply, yawns suck in O2 and expel CO2, bringing the gases back to normal.
Arterial blood gases Increased CO2, reduced O2 in the circulation.
Theories on contagious yawning
• Physiology Yawning reflex is triggered by a need for more oxygen. When others watch a yawner, the need for O2 becomes nearly conscious, triggering a chorus of yawns in response
• Boredom Yawning is a social display that signals to others that the yawner finds X, Y, or Z tedious or dull. Odds are good he’s not alone and others may join the impromptu club
• Evolutionary Yawning is holdover from cave-dwelling, in which the yawner is in fact displaying teeth-baring dominance, which triggers some primordial message
The above, per researchers at Columbia…but they’re just guessing