我們為什麼會打哈欠？：英語精讀講義

Almost all animals with a spine yawn. 文法

幾乎所有有脊椎的動物都會打哈欠。

Penguins do it as a mating ritual,

企鵝把打哈欠當作求偶儀式，

snakes do it to realign their jaws after a meal

蛇在進食後靠打哈欠讓下顎重新對齊，

and guinea pigs do it to display anger.

而天竺鼠則用打哈欠來表達憤怒。

So why exactly do humans yawn? 語氣意圖

那麼，人類究竟為什麼會打哈欠呢？

And is yawning actually contagious? 用詞

而且，打哈欠真的會傳染嗎？

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

如果你還沒看過我們的「哈欠計時器」影片，

click here or use the link in the description

請點這裡，或使用說明欄中的連結，

to see how long you can last before yawning. 文法

看看你能撐多久不打哈欠。

If you're anything like us, 片語搭配

如果你和我們差不多，

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

你可能光看這部影片的標題就已經打哈欠了。

The truth is,

事實上，

the first time you yawned was likely as a fetus.

你第一次打哈欠，很可能還是在胎兒時期。

Babies begin to yawn during the second trimester

寶寶從懷孕中期就開始打哈欠，

and though the reason why is still unknown, 文法

雖然原因仍不清楚，

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

但這可能與大腦的正常發育有關。

In adults,

對成年人來說，

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

過去人們普遍認為，打哈欠能讓肺部吸入更多氧氣，

making you feel less tired, 文法

從而讓人沒那麼疲倦，

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

但新研究指出，事實可能並非如此。

Scientists now believe that yawning has developed

如今科學家認為，打哈欠這種行為之所以演化出來，

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

是為了透過生理機制幫大腦降溫。

Much like a computer, 表達脈絡

就像電腦一樣，

your brain works best at a certain temperature

大腦在特定溫度下運作得最好，

and tries to avoid overheating.

並會設法避免過熱。

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

事實證明，打哈欠會提高心率，

blood flow,

加快血液流動，

and the use of muscles in your face,

並帶動臉部肌肉，

which are all essential to cooling the brain. 文法

而這些對大腦降溫都至關重要。

On top of that, 表達脈絡

除此之外，

deeply inhaling cold air can alter the temperature

深深吸入冷空氣還能改變

of the blood in our head.

我們頭部血液的溫度。

But why is your brain hot in the first place? 慣用語

可是，大腦一開始為什麼會發熱呢？

Well,

其實，

both exhaustion and sleep deprivation are known 用詞

眾所周知，精疲力竭和睡眠不足都會

to increase overall brain temperature,

提高大腦的整體溫度，

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

這就解釋了為什麼人在這些狀態下更容易打哈欠。

Researchers have even found participants

研究人員甚至發現，參與者

who place warm packs on their head

把熱敷袋放在頭上時，

yawn 41% of the time 片語搭配

有41%的時間會打哈欠，

while watching others yawn 文法

當時他們正在看別人打哈欠；

as opposed to 9% of the time 表達脈絡

相較之下，這個比例只有9%，

with a cold pack on their head.

如果他們頭上放的是冷敷袋。

So if your head is already cold,

所以，如果你的頭本來就很涼，

you'll yawn less.

你打哈欠的次數就會比較少。

But what about contagious or social yawning? 表達脈絡

那麼，傳染性或社交性打哈欠又是怎麼回事？

Humans, primates, and even dogs

人類、靈長類動物，甚至狗

find yawning contagious 文法

都會被哈欠傳染，

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

而這很可能與同理心有關。

Contagious yawning begins in children

兒童開始出現傳染性打哈欠，

around the age of 4 to 5

大約是在四到五歲時，

and this is when empathetic behavior,

而這個階段也正是同理行為

along with the ability to identify emotions, 片語搭配

以及辨識情緒的能力

begins to develop.

開始發展的時候。

In fact,

事實上，

children with empathy-related disorders such as autism

患有自閉症等同理心相關障礙的兒童

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

看到別人打哈欠的影片時，打哈欠的次數

compared to other children.

比其他兒童更少。

Research also suggests that you're more likely 文法

研究也顯示，你更有可能

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

跟著在社交關係或血緣關係上與你親近的人打哈欠。

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

就連狗也更容易跟著主人打哈欠，

as opposed to the yawn of a stranger.

而不是跟著陌生人打哈欠。

Finally,

最後，

mirror neurons also play a role. 片語搭配

鏡像神經元也在其中發揮作用。

In our brain,

在我們的大腦中，

mirror neurons fire when we perform a specific action, 用詞

當我們做出某個特定動作時，鏡像神經元會被活化；

view someone else doing the action,

當我們看到別人做這個動作時，

or even just hear someone talk about the action.

甚至只是聽別人談到這個動作時，也會如此。

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

它們是重要的腦細胞，可用於學習、

self-awareness,

自我認知

and relating to others. 用詞

以及與他人建立連結。

When we view someone else yawn,

當我們看到別人打哈欠時，

the mirror neurons in our brain become activated

大腦中的鏡像神經元會被活化，

in a similar way

活化方式也很類似，

and as a result, 表達脈絡

因此，

we copy the yawn.

我們也會跟著打哈欠。

So although yawning may occur in people

所以，儘管打哈欠可能會發生在

who are literally hot-headed, 慣用語

真正「腦袋發熱」的人身上，

contagious yawning allows us to be cool

傳染性打哈欠卻能讓我們

with the people around us.

與身邊的人更「合拍」。

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

如果你還沒試過我們的「哈欠計時器」，

go try it out

快去試試看，

and let us know in the comments

然後在留言區告訴我們，

how long you were able to last

你撐了多久，

and subscribe for more weekly science videos.

並訂閱頻道，收看我們每週更新的科學影片。