Hello everyone, Julian here for DNews.

大家好，今天由Julia主持 DNews。

Nipples: everybody has them, but you probably don’t pay them much attention.

乳頭：人人都有乳頭，但是你可能並沒有太在意它們。

That is unless you’re cold, aroused, or talking about science

除非你感覺到冷、性慾被激起或者是談論科學的時候

and your little bosom buddies decide to stand at attention for all the world to see.

你的乳頭就會立起來引起全世界的注意。

How do nipples get hard, and what purpose does this serve?

乳頭是如何立起來的？乳頭立起來有什麼作用呢？

Answering the how is a bit easier than answering the why, especially thanks to a recent study published in Nature Neuroscience.

回答如何立起來這個問題，要比回答為什麼立起來更加容易些，尤其是多虧了最近發表在《自然神經科學》的一個研究

Researchers were interested in the sympathetic nervous system, which is

研究者們對交感神經系統的研究很感興趣

most known for its role in the fight-or-flight response.

其最廣為人知的就是它的戰鬥或逃跑反應功能 (譯註: fight-or-flight response為心理與生理學名詞，是表示機體經一系列神經與腺體反應刺激後引起壓力，使軀體做好防禦、掙扎或逃跑的準備)

If you’re not familiar with it, of course we’ve covered it, and

如果你對此不熟悉，沒關係我們會對它進行解釋，並且

you can check out that video to learn about it in-depth.

你還可以透過影片來進行深入瞭解。

But back to the researchers -- When they were examining the sympathetic nervous system in mice,

繼續之前關於研究者的談論－－當他們檢查老鼠的交感神經系統時，

the researchers found that it was more specialized to respond to specific stimuli than previously assumed.

與之前做的假設相比，他們發現特定刺激做出的反應更加特化。

The scientists followed nerves in the system from where they originated in the spinal cord

科學家們追蹤的神經從脊髓開始

to where they connect to other structures like the blood vessels, muscles, and yes,

到連結其他結構的構造，例如血管、肌肉，當然還有

nipples.

乳頭

They found there were 8 distinct types of neurons wired to specific areas, each expressing

他們發現有八種不同的神經元圍繞在不同的區域，每一種

different genes and responding to different stimuli.

都呈現不同的基因並且對不同的刺激做出反應。

So there is actually a type of neuron that exists just to make your nipples erect.

因此事實上真的有一種神經元，它的功能就是讓乳頭站立。

When these neurons are activated by the neurotransmitter norepinephrine, they cause erector muscles

當這些神經元被去甲基腎上腺素神經傳遞素活化之後，就會引起豎立肌

to contract, tightening your areola and causing your milk duds to harden.

收縮，讓你的乳暈變緊，並使奶頭變硬。

Titillating as this information is, it still doesn’t answer why nipples need to get hard

雖然這些資訊能「挑逗起」你對乳頭的興趣，但它始終沒有解答我們一開始問的「為什麼

in the first place.

乳頭會立起來」

What’s the point of the point?

這些點（指乳頭）的重點是什麼？

The most obvious reason is for breast feeding.

最顯而易見的理由是哺乳。

A baby’s suckling reflex is activated when something strokes the roof of their mouth,

當嬰兒的上顎觸碰到乳頭時才會讓他們開始吮吸

so a stiff nipple will help get the little sucker to latch on for a meal.

所以豎立起來的乳頭可以幫助寶寶們知道如何餵飽他們自己。

But what about when it’s time to make a baby, or when it’s cold, or when nipples

但如果是在做愛或是溫度太冷的時候，或者乳頭

go rogue and pitch a shirt-tent for no obvious reason?

毫無緣由地豎立起來呢？

Science is a little more perplexed about that.

目前的科學對此尚未能予以更進一步的解答

It’s possible that hard nipples are supposed to serve as a signal of arousal, but it’s

站立的乳頭可能被認為是性慾被激起的反應，但是

a pretty terrible signal if it also shows up just because it’s cold.

如果是因為天氣太冷，而乳頭立起來那就會有點難以解釋了。

That’s like having a thermometer where all the numbers are replaced with winking emojis,

就像是一個溫度計上面的數字都被調皮的眨眼表情所替代，

it tells you nothing!

因為它什麼都沒告訴你！

It’s possible we get nipply when it’s nippy because the muscles in our areolas and

我們的乳頭有反應有可能是因為冷而引起的，因為乳暈的肌肉和

under our hair follicles respond to the same stimuli. The scientists who discovered what

毛囊會對同樣的刺激做出反應。發現之前被我稱作「乳頭神經元」的科學家

I will heretofore call the “nipple neuron” found another kind of neuron that also responds

還發現了另一種神經元同樣可以對去甲基腎上腺素做出反應

to norepinephrine and causes your hair to stand on end.

也能使你的毛髮豎立起來。

This might be a vestigial trait from when we were more hirsute, and our hair puffed

這有可能是我們從過去毛髮很多很蓬鬆，甚至能利用毛髮將空氣包住來保暖

out to trap air and keep us warmer.

演化而來的痕跡性狀

It’s also frequently suggested our hair rises in stressful situations in an effort

還有另一個十分常見的解釋是，處於一個壓力十足的環境下，毛髮會自動豎起

to make us look bigger.

讓我們的體型看起來更大一些。

You can imagine how puffed out hair would be helpful when you’re being attacked by

你可以想像當你遭遇捕獵者攻擊時，全身豎立的毛髮會多麼有用

a predator, though it’s a little harder to see how stiff nips will intimidate a bear.

但是卻很難想像豎立的乳頭可以威嚇到一隻熊。

Maybe it’ll think you’re aroused and be kind of weirded out.

或許牠會以為你性慾被激起，然後表現得有些奇怪。

If the only surefire reason nipples get stiff is to help with breastfeeding, then why do

如果乳頭豎立起來的確切原因是幫助哺乳，那麼為什麼

men even have nipples?

男人也會有乳頭呢？

It’s a classic question, and it’s one that deserves a classic episode, so I’ll

這是個經典的問題，這個問題值得再做另一集節目來加以探討，所以有請

let Laci Green explain it here.

Laci Green 來為我們解釋。

The human body is totally fascinating and awesome and if there are any weird bodily

人體簡直是太神奇了，如果有任何關於身體有趣奇異的現象

phenomenons you’d like us to explain, tell us!

希望我們為你解釋的，請告訴我們！

You can let us know in the comments, subscribe for more and I'll see you guys next time on DNews.

你可以透過評論讓我們知道、訂閱我們頻道以瞭解更多，我們下期 DNews 再見。