If you've ever visited a zoo, you've probably seenanimals yawn. You might have thought those yawnswere a result of boredom, but research hassuggested that most animals do not yawn forprecisely the same reasons as humans.

如果你曾参观过动物园，那你可能看见过动物们打哈欠。你可能会想，这是因为动物们也感到无聊，但研究表明大多数动物打哈欠是出于与人类不同的原因。

Both humans and animals yawn to become morealert, but humans tend to yawn when they arebored or sleepy. And animals yawn in anticipationof a stimulating situation. When a human feels bored or sleepy, their blood flow becomes a bitsluggish and the brain gets less oxygen. As a result, they yawn in order to supply the brainwith extra oxygen which helps them become more alert.

人类和动物打哈欠都能使自身变得更警惕，但是人类倾向于在无聊或者困乏的时候打哈欠。而动物打哈欠则是因为预期的刺激。当人们感到无聊或者困乏的时候，人体内的血液流动速度稍微减慢，于是造成大脑缺氧。因此人们打哈欠是为了给大脑补充氧气，这样人才能变得更警觉。

Most research has suggested that, contrary to common belief, we don't yawn because ourbrains need extra oxygen, but because we need to become more alert. Instead of yawning inorder to help raise alertness levels during boring situations, animals yawn in anticipation ofexciting situations. One scientist has spent hundreds of hours observing the yawning patterns ofseveral animal species, including lions, monkeys and humans.

与普遍观念相反的是，大多数研究表明我们并不是因为大脑缺氧才打哈欠，而是因为我们需要变得更警觉。与人类在无聊的情况下为了保持警觉性而打哈欠相反，动物会因令其兴奋的事情即将发生而打哈欠。一位科学家花了几百个小时观察几种动物的打哈欠模式，包括狮子、猴子和人类。

He found that human beings yawned most often in situations with minimal stimulation, butin which alertness was important, such as driving late at night; they yawned least often duringphysically stimulating situations such as an aerobics class.

他发现人类打哈欠多数处在刺激最小的情况下，同时也是警觉性很重要的情况下，例如在深夜驾车;当他们身理上受到刺激时打哈欠最少，例如上有氧运动课。

Captive lions and monkeys, on the other hand, yawned most often just before feeding time, oneof the most stimulating times of the day. Other scientists have also observed laboratory ratsyawning just prior to eating. These studies suggest that animals yawn in anticipation ofstimulation rather than as a result of boredom.

另一方面，圈养的狮子和猴子在喂食时间前总是打哈欠。喂食是一天中刺激最大的时刻。其他科学家们也观察过实验室的老鼠，发现它们总是在吃饭之前打哈欠。这些研究表明动物打哈欠不是因为无聊，而是因为预期的刺激。