Yawning may be less a response to boredom than a natural mechanism for cooling off overheated brains, new research says. The human brain operates optimally when cool, much like a computer, and conditions like fatigue actually cause the organ to heat up, ABC News reports. A quick gulp of air can offer relief to sweltering skulls.
The University of Albany professor who led the study offers an explanation for the phenomenon of contagious yawning: survival. Early humans keeping watch against attacks would have risked death if they nodded off. "If everyone yawns in response to seeing someone yawn, it reinstates an optimal level of vigilance on the part of people in the group," he says.