Nobody Knows Why We Yawn
To yawn is to open the mouth wide involuntarily. Its purpose remains genuinely unexplained.
To yawn is to open the mouth wide and inhale deeply, usually from tiredness or boredom. Its function is still unresolved. The old explanation about low oxygen was tested and failed: breathing extra oxygen does not stop yawning. Current theories favour brain cooling or a shift in alertness, but none is settled. Contagious yawning is better understood as a social phenomenon, stronger between people who know each other well, and it occurs in chimpanzees and dogs too.
- To open the mouth. *Yawning widely.*
- A yawn. *A loud yawn.*
- A gaping space. *A yawning gap.*
- Contagious yawning. *Contagious yawning.*
- Old English — *ginian*. *The source.*
Word forms
| Form | Word | Example |
|---|---|---|
| Verb | yawn | Yawning. |
| Noun | yawn | A yawn. |
| Adjective | yawning | A yawning chasm. |
| Past | yawned | Yawned. |
| Old English | ginian | To gape. |
- She yawned in the meeting.Tiredness.
- A yawning gap opened.Figurative.
- The oxygen theory failed.Science.
What is known about yawning
- The oxygen theory was tested and does not hold
- Brain cooling is a leading current hypothesis
- It occurs before birth, in the womb
- Contagious yawning is stronger between close acquaintances
- Chimpanzees and dogs also catch yawns
Old English *ginian* and *geonian*, to gape, of Germanic origin.
Do we yawn because of low oxygen?
No. Experiments with extra oxygen showed no effect on yawning, and that explanation has been abandoned.
Why is yawning contagious?
It appears to be social rather than physiological, and is strongest between people who know each other well.