The act of yawning to increase oxygenation probably evolved across thousands of years *and especially during eras of poor housing ventilation and overpopulation. Those who were not genetically programmed to compete for air became victims to Darwin.
Thats why you yawn when you notice someone else yawn.
Submitted November 02, 2018 at 12:08PM by banniemd2b https://ift.tt/2QdZ36d