The Yawn of the Wild

When someone yawns publicly, people may think he is impolite—or at least extremely bored. Rules of etiquette notwithstanding, yawning actually serves quite a useful purpose. A yawn is an involuntary inhalation. We usually yawn in the evening when we are fatigued by the day’s activities or in the morning after we wake up. A deep yawn serves to increase our supply of oxygen and may refresh us momentarily; it is often part of the awakening process.

But did you know that animals also yawn, although not always for better ventilation? The reason they do so is often quite fascinating. Monkeys, for example, sometimes yawn in order to communicate a message. The wide open mouth and fierce display of teeth is a way of flashing a warning to a rival male monkey or a would-be predator. The message: ‘I have a fearsome bite. Keep your distance!’

It has also been observed that predatory cats of the African plains will often stretch and yawn before setting out to hunt. As with humans, the cats’ yawn serves a physiological function—that of taking extra air into the lungs. This increases the oxygen in the blood. The heart then rushes it to other parts of the body, providing instant energy for short high-speed chases.

Why, even fish have been observed yawning! The book Inside the Animal World tells of fish that sometimes “yawn as a prelude to moving quickly. . . . A fish may yawn also when it is excited or when it sees an enemy or sees food, all occasions when rapid action is needed.”

Probably the most impressive yawn of all is that of the hippopotamus, or Behemoth. This bulky creature can stretch open its huge cavern of a mouth an incredible 150 degrees! The yawn enables an old bull hippo to show everyone else in the hippo pool who is boss. It also serves as a toothy warning to any intruders who would dare trespass into his river domain.

So while it may not evoke the drama of a lion’s roar, a yawn—whether a sleepy yawn, a threatening yawn, or simply an energizing yawn—does serve a beneficial purpose. It is just one more example of the astonishing creativity of the Designer of the animal kingdom!