科学美国人60秒:Yawns Help the Brain Keep Its Cool

Not many scientific studies begin like this: "Many hours of watching YouTube clips. Trying to find as many yawns as possible." But for Andrew Gallup, an evolutionary psychologist who studies yawning at the State University of New York, it was all in a day's work.
很多科学研究都不是这样开始：“花费数小时观看YouTube视频，试图找到更多的打哈欠片段。”但是，对于安德鲁·盖洛普，纽约大学研究哈欠的进化心理学家，这每天的工作。

Gallup says yawns have traditionally been known as a sign of sleepiness, or boredom. "But recent evidence suggests that yawning may function to promote brain cooling." The idea being, when you breathe in deeply, the incoming air slightly cools the brain. And stretching the jaw increases blood flow to the brain too--another cooling factor. Reason we do it at night? "At night time when we're about to go to sleep our brain and body temperatures are at their highest point throughout the day."
盖洛普表示，传统意义上而言，人们将打哈欠视为疲倦、厌烦的象征。“但是，最近的研究结果表明，打哈欠可以帮助大脑降温。”理论就是，当你深呼吸的时候，吸入的空气会使大脑降温。伸展下巴也会增加血液流入大脑——这是导致大脑降温的另一个因素。为什么我们经常在晚上打哈欠呢?“在晚上我们要入睡的时，我们的大脑温度和体温为一天当中最高。

And so Gallup and his colleagues found themselves hunting for cat videos on the internet--<>--but also clips of dogs, foxes, elephants, gorillas, hedgehogs, squirrels, rats, and walruses yawning. They timed all those yawns--then compared them to each species' average brain weight, and the number of neurons in the cerebral cortex.
盖洛普和同事们在网上寻找猫咪打哈欠视频——同时还有狗、狐狸、大象、大猩猩、刺猬、松鼠、老鼠以及海象打哈欠的视频。他们将所有的哈欠计时——然后将其与物种的平均大脑重量以及大脑皮层神经元的数量相比。

Their conclusion, published in Biology Letters, was that the length of a yawn was a remarkably good predictor of an animal's brain weight, and cortical neuron number--regardless of the size of its skull, or jawbone.
该研究结果发表在《生物学报》上：哈欠的长度可以预测动物大脑的重量以及皮质神经元的数量——忽略动物的骨骼以及头骨大小。

"What that really represents is that yawning likely serves this very basic, and fundamental neurophysiological function." In other words--it helps the brain keep its cool.
研究结果真正想表明的是，打哈欠具有基础的神经生理功能。换而言之，它可以帮助大脑降温。