The Science of Why We Yawn

Yawning is a universal human behavior. We yawn when we are tired, when we wake up, and sometimes when we are simply bored. Surprisingly, we also yawn when we see someone else yawning. Despite how common it is, scientists have debated the exact purpose of yawning for centuries.

Historically, people believed that yawning was the body's way of taking in more oxygen and releasing excess carbon dioxide. However, recent scientific research suggests a different explanation: thermoregulation. The brain functions best within a specific temperature range. When we become sleepy or inactive, the brain's temperature rises slightly. Yawning acts like a cooling system. Deep inhalation brings cool air into the nasal passages and mouth, cooling the blood vessels that lead directly to the brain.

Another fascinating aspect of yawning is its contagious nature. When an adult sees, hears, or even thinks about yawning, there is a high probability they will yawn as well. Psychologists believe this social response is connected to empathy—the ability to understand and share the feelings of others. Studies show that contagious yawning is most common among close friends and family members, suggesting that social bonding plays a role in this involuntary physical action.

COMPREHENSION & VOCABULARY QUESTIONS:

1. What was the traditional theory about why humans yawn, and how does recent research contradict it?

2. What role does "thermoregulation" play in brain function?

3. Define the word "involuntary" as used in the text.

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