我们为什么会打哈欠？：英语精读讲义

Almost all animals with a spine yawn. 語法

几乎所有有脊椎的动物都会打哈欠。

Penguins do it as a mating ritual,

企鹅把打哈欠当作求偶仪式，

snakes do it to realign their jaws after a meal

蛇在进食后靠打哈欠让下颌重新对齐，

and guinea pigs do it to display anger.

而豚鼠则用打哈欠来表达愤怒。

So why exactly do humans yawn? 語氣意圖

那么，人类究竟为什么会打哈欠呢？

And is yawning actually contagious? 用詞

而且，打哈欠真的会传染吗？

If you haven't already checked out our yawn-o-meter video, 短語動詞

如果你还没看过我们的“哈欠计时器”视频，

click here or use the link in the description

请点击这里，或使用简介中的链接，

to see how long you can last before yawning. 語法

看看你能坚持多久不打哈欠。

If you're anything like us, 短語搭配

如果你和我们差不多，

you may have even yawned at the title of this video. 語法

你可能光看这个视频的标题就已经打哈欠了。

The truth is,

事实上，

the first time you yawned was likely as a fetus.

你第一次打哈欠，很可能还是胎儿的时候。

Babies begin to yawn during the second trimester

宝宝从孕中期就开始打哈欠，

and though the reason why is still unknown, 語法

虽然原因仍不清楚，

it may have to do with proper brain development. 短語搭配

但这可能与大脑的正常发育有关。

In adults,

对成年人来说，

yawns were commonly thought to draw more oxygen into the lungs, 語法

人们过去普遍认为，打哈欠能让肺部吸入更多氧气，

making you feel less tired, 語法

从而让人不那么疲倦，

but new research states that this may not be the case. 短語搭配

但新研究表明，事实可能并非如此。

Scientists now believe that yawning has developed

科学家如今认为，打哈欠这种行为之所以演化出来，

as a way of physiologically cooling your brain. 短語搭配

是为了通过生理机制给大脑降温。

Much like a computer, 表達脈絡

就像电脑一样，

your brain works best at a certain temperature

大脑在特定温度下运转得最好，

and tries to avoid overheating.

并会设法避免过热。

And it turns out yawning increases your heart rate, 表達脈絡

事实证明，打哈欠会提高心率，

blood flow,

加快血液流动，

and the use of muscles in your face,

并调动面部肌肉，

which are all essential to cooling the brain. 語法

而这些对大脑降温都至关重要。

On top of that, 表達脈絡

除此之外，

deeply inhaling cold air can alter the temperature

深深吸入冷空气还能改变

of the blood in our head.

我们头部血液的温度。

But why is your brain hot in the first place? 習語

可是，大脑一开始为什么会发热呢？

Well,

其实，

both exhaustion and sleep deprivation are known 用詞

众所周知，精疲力竭和睡眠不足都会

to increase overall brain temperature,

提高大脑的整体温度，

which explains why yawning occurs more in these states. 表達脈絡

这就解释了为什么人在这些状态下更容易打哈欠。

Researchers have even found participants

研究人员甚至发现，参与者

who place warm packs on their head

把热敷袋放在头上时，

yawn 41% of the time 短語搭配

有41%的时间会打哈欠，

while watching others yawn 語法

当时他们正在观看别人打哈欠；

as opposed to 9% of the time 表達脈絡

相比之下，这一比例只有9%，

with a cold pack on their head.

如果他们头上放的是冷敷袋。

So if your head is already cold,

所以，如果你的头本来就很凉，

you'll yawn less.

你打哈欠的次数就会更少。

But what about contagious or social yawning? 表達脈絡

那么，传染性或社交性打哈欠又是怎么回事？

Humans, primates, and even dogs

人类、灵长类动物，甚至狗

find yawning contagious 語法

都会被哈欠传染，

and it's most likely linked to empathy. 短語搭配

而这很可能与同理心有关。

Contagious yawning begins in children

儿童开始出现传染性打哈欠，

around the age of 4 to 5

大约是在四到五岁时，

and this is when empathetic behavior,

而这个阶段也正是同理行为

along with the ability to identify emotions, 短語搭配

以及识别情绪的能力

begins to develop.

开始发展的时候。

In fact,

事实上，

children with empathy-related disorders such as autism

患有自闭症等同理心相关障碍的儿童

yawn less in response to videos of people yawning 短語搭配

看到别人打哈欠的视频时，打哈欠的次数

compared to other children.

比其他儿童更少。

Research also suggests that you're more likely 語法

研究还表明，你更有可能

to copy the yawn of someone socially or genetically close to you. 用詞

跟着在社交关系或血缘关系上与你亲近的人打哈欠。

Even dogs are more likely to copy the yawns of their owner

就连狗也更容易跟着主人打哈欠，

as opposed to the yawn of a stranger.

而不是跟着陌生人打哈欠。

Finally,

最后，

mirror neurons also play a role. 短語搭配

镜像神经元也在其中发挥作用。

In our brain,

在我们的大脑中，

mirror neurons fire when we perform a specific action, 用詞

当我们做出某个特定动作时，镜像神经元会被激活；

view someone else doing the action,

当我们看到别人做这个动作时，

or even just hear someone talk about the action.

甚至只是听别人谈起这个动作时，也会如此。

They're important brain cells that are used for learning,

它们是重要的脑细胞，可用于学习、

self-awareness,

自我认知

and relating to others. 用詞

以及与他人建立联系。

When we view someone else yawn,

当我们看到别人打哈欠时，

the mirror neurons in our brain become activated

大脑中的镜像神经元会被激活，

in a similar way

激活方式也很相似，

and as a result, 表達脈絡

因此，

we copy the yawn.

我们也会跟着打哈欠。

So although yawning may occur in people

所以，尽管打哈欠可能会发生在

who are literally hot-headed, 習語

真正“脑袋发热”的人身上，

contagious yawning allows us to be cool

传染性打哈欠却能让我们

with the people around us.

与身边的人更“合拍”。

If you haven't already checked out our yawn-o-meter,

如果你还没试过我们的“哈欠计时器”，

go try it out

快去试试看，

and let us know in the comments

然后在评论区告诉我们，

how long you were able to last

你坚持了多久，

and subscribe for more weekly science videos.

并订阅频道，收看我们每周更新的科学视频。