"Why are yawns contagious? We asked a scientist" by Teresa Carey One theory argues that when humans are tired, we stop taking deep breaths, which causes a build-up of carbon dioxide in the body, said Douglas Parham, a speech scientist at Wichita State University. A yawn might be a special kind of respiration, Parham said. It builds up oxygen quickly, while expelling carbon dioxide, even more than a deep breath. Excess carbon dioxide and other chemical changes, such as a drop in oxygen or increase in a compound called adenosine, could also act as “yawn gates,” said James Giordano, a neuroethicist and neuroscientist at Georgetown University. These chemicals send out a signal that triggers a yawn. By yawning, we compress the muscles of the face, driving oxygen-enriched blood to the brain, Giordano said. Other proposals state the purpose of yawning is to cool the brain, or to stretch internal organs like tissues and lungs, helping the body to liven up. Despite being a fundamental part of our lives, information on yawning is thin, said Thomas Scammell, a neurologist at Harvard Medical School who studies sleep. But he added that yawning is a primitive reflex among many animals that originates in the brain stem. Because the brain stem of humans is similar to other mammals (and birds and reptiles too), it makes sense that most animals yawn, Scammell said. Indeed, birds, reptiles, mammals and some sharks can yawn — and animals with bigger brains tend to yawn longer. “That puts a little bit of support back in the theory that what yawning is really doing is changing the brain chemistry,” Giordano said, adding that scientists are still trying to investigate the reasons why. What is known is that the behavior is contagious. The likelihood of yawning increases sixfold, according to one study, after seeing someone else yawn. As for yawn contagion, Giordano said it may be related to a phenomenon called social mirroring, where organisms imitate the actions of others. Other b

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"Why are yawns contagious? We asked a scientist" by Teresa Carey  One theory argues that when humans are tired, we stop taking deep breaths, which causes a build-up of carbon dioxide in the body, said Douglas Parham, a speech scientist at Wichita State University. A yawn might be a special kind of respiration, Parham said. It builds up oxygen quickly, while expelling carbon dioxide, even more than a deep breath.  Excess carbon dioxide and other chemical changes, such as a drop in oxygen or increase in a compound called adenosine, could also act as “yawn gates,” said James Giordano, a neuroethicist and neuroscientist at Georgetown University. These chemicals send out a signal that triggers a yawn. By yawning, we compress the muscles of the face, driving oxygen-enriched blood to the brain, Giordano said.  Other proposals state the purpose of yawning is to cool the brain, or to stretch internal organs like tissues and lungs, helping the body to liven up.  Despite being a fundamental part of our lives, information on yawning is thin, said Thomas Scammell, a neurologist at Harvard Medical School who studies sleep. But he added that yawning is a primitive reflex among many animals that originates in the brain stem.  Because the brain stem of humans is similar to other mammals (and birds and reptiles too), it makes sense that most animals yawn, Scammell said. Indeed, birds, reptiles, mammals and some sharks can yawn — and animals with bigger brains tend to yawn longer.  “That puts a little bit of support back in the theory that what yawning is really doing is changing the brain chemistry,” Giordano said, adding that scientists are still trying to investigate the reasons why.  What is known is that the behavior is contagious. The likelihood of yawning increases sixfold, according to one study, after seeing someone else yawn.  As for yawn contagion, Giordano said it may be related to a phenomenon called social mirroring, where organisms imitate the actions of others. Other b

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ehaviors, such as laughing or crying, can also be contagious in this way. This social mirroring may have evolved as a means of building social bonds and fostering group cohesion. When one individual yawns, it could signal to others that it's time to rest or re-energize, promoting synchronization within a group.

Parham adds that yawning could serve an important communicative function; it's a way of signaling to others in our social group that we are tired or in need of a break. This could be especially relevant in social or group settings, where maintaining alertness and stamina is important for the group's activities.

Additionally, there might be a neurological basis for the contagious nature of yawning. Studies have shown that people who are more empathetic are more likely to yawn after witnessing someone else do so. This suggests a connection between emotional and physiological responses, indicating that yawning could be linked to our ability to bond with others and understand their emotional states.

In summary, yawning remains a complex behavior with various potential functions, including regulating brain chemistry, communicating fatigue, cooling the brain, and promoting social bonding. Scientists continue to explore the intricacies of this behavior, seeking to uncover the underlying mechanisms and evolutionary significance of why yawns are not only a common reflex but also remarkably contagious.