Like "Why are barns red?" and “What's up with gluten?”We here at SciShow are all about fostering curiosity.

像「穀倉為什麼是紅色的？」、「為什麼麩質吃多了不好？」SciShow 的宗旨正是激發你的好奇心

That's why we've worked with Google and YouTube to answer ten of the most popular questions searched on the internet.

所以我們與 Google 及 YouTube 合作，替你解答十大網路熱搜

This is The World's Most Asked Questions.

新單元「全世界都在問的問題」

Today's question: What is love?

今日主題：愛是什麼？

It's the kind of thing that keeps poets and philosophers up at night,

這問題讓詩人和哲學家想破了頭

but science actually has a pretty good explanation for it, too.

但其實很容易用科學解釋

Actually, several explanations.

事實上，解釋還真多

And the answer might change depending on what kind of scientist you ask.

答案可能因不同領域的科學家而異

A biologist would say it's all about reproduction, and the evolution and survival of a species.

生物學家說愛是傳宗接代，關乎物種的進化與生存

A psychologist may go on about our need for togetherness and acceptance.

心理學家可能會說，愛是渴求陪伴與接納

But possibly the best way to understand love is through chemistry. Brain chemistry.

不過，說愛是大腦的化學反應，也許最爲合理，大腦化學

Although the heart is our symbol of love for some reason,

雖然心形一直被視為愛的記號

when it comes down to it, love is all about the brain.

但追根究底大腦才是關鍵

We know this because we can actually see love in action in brain scans.

透過掃描，我們確實看見「愛」在大腦中運作

And you know what? It looks awful like a brain on cocaine.

你知道嗎？愛的大腦反應超像喀藥

As a person first falls in love, at least a dozen different brain parts light up to release powerful chemicals --hormones and neurotransmitters

一旦陷入愛河，大腦多處受刺激而釋放強大的化學物，荷爾蒙與神經介質

that trigger feelings of excitement, euphoria, bonding, and butterflies.

引發興奮、愉悅、親密感，還讓你小鹿亂撞

Research also shows that the kind of unconditional love between a mother and child activates slightly different regions of the brain.

研究也顯示，母親對孩子無條件的愛啟動的腦部中不同的區域

Early romantic love and attraction, what you might call passion, is all about flooding the brain's reward systems

戀愛初期的激情，以海嘯之姿沖刷大腦的「獎酬系統」

in a tsunami of feel-good chemicals like adrenaline, norepinephrine, and dopamine.

產生感覺良好物質，如腎上腺素、正腎上腺素和多巴胺

This is why a brain on intense new love looks a whole lot like a brain on coke

所以墜入情網時，大腦就像喀了古柯鹼一樣

adrenaline and norepinephrine amp up your heart rate and get you all restless,

腎上腺素和正腎上腺素提高心跳速率，使你心神不寧

while those dopamine drips leave you feeling euphoric.

而多巴胺讓你快樂似神仙

These chemicals light up your brain's pleasure centers, lowering your pleasure thresholds,

這些物質刺激「愉悅中樞」，降低你的快樂門檻

and making it easier to feel good about...everything.

所以你能輕易對任何事感到開心

Interestingly, this kind of passionate new love is also marked by lowered serotonin levels,

有趣的是，為愛痴狂的特徵是血清素濃度降低

similar to those found in people with obsessive-compulsive disorders

與強迫症患者相似，

which may help explain those 30 texts your infatuated new lover sent while you were in the shower.

這也許可以解釋為何只是洗個澡，情人卻瘋傳 30 封簡訊給你

Eventually, most of these more intense, obsessive components of new love settle down

這種令人窒息的愛終將逐漸緩和，

into a deeper, calmer form of love associated with attachment and bonding.

取而代之的是深切平靜的愛，親密地相互依賴

Here your brain chemistry starts changing again, and hormones like oxytocin and vasopressin take over.

這時大腦再次起變化，由催產素和升壓素接管

Their mission, like Al Green's, is to get you to stay together.

它們的使命是讓你們緊緊相依，就像那首艾爾格林的歌

You may have heard of oxytocin, the so-called the "cuddle hormone."

你也許聽過催產素，所謂的「擁抱荷爾蒙」

It gets released during orgasms, and for women during childbirth, and it helps cement bonds between people.

它在高潮或分娩時釋放，有助鞏固兩人情感

And you can think of vasopressin as the monogamy hormone.

而升壓素有點像「忠誠荷爾蒙」

And you know who's taught us more about how it works than anything else?

誰把「忠誠荷爾蒙」發揮得最淋漓盡致呢？

Prairie voles, one of the very few mammals that mate for life.

草園田鼠，牠們是少數一夫一妻的哺乳類動物

After mating, a male vole's brain gets flooded with vasopressin, and essentially gets hooked on his mate forever.

公田鼠在交配後腦部充滿升壓素，從此對母田鼠死心踏地

The two then have lots of sex, and all that tiny boot-knocking keeps the vasopressin flowing.

兩隻小傢伙瘋狂的嘿咻，愛的撞擊使升壓素源源不絕

When researchers gave voles a compound that suppressed the effects of vasopressin,

當研究人員對其施打抗升壓素的藥物後

the pairs quicklyfell apart, losing their devotion to each other.

這對愛侶便很快分開，不再對彼此忠貞

So, while in the poetic sense, love may always be something of a mystery,

以詩的角度來看，愛情可能永遠是個難解的謎

from the scientific view, it is within the realm of comprehension.

但從科學的角度來看，它其實是個可以理解的領域

But what about you? How are the love lives of the SciShow viewers?

你呢？SciShow 觀眾們的感情世界又是如何？

Well, of our survey takers, people within the ages of 51 and 60 are the most likely to have been in love.

據我們調查，51-60 歲的人最有可能墜入情網

People who got their energy most from exercise were also more likely to have been in love.

因運動而活力充沛的人也比較容易戀愛

On the other hand, people who said they got their energy from food were less likely to have been in love.

另一方面，說自己靠吃東西補充能量的人則感情空洞

Of all the fascinating questions in the world, what question do you want answered most?

世界上千奇百怪的問題這麼多，你最想知道什麼？

Let us know on Facebook or Twitter or in the comments down below, and we will answer the best questions in a new video at the end of the month.

請上 Facebook 或 Twitter 告訴我們，或在下方留言，月底將選出最酷的問題來回答

And don't forget to use the hashtag #WMAQ and stay tuned for other videos this week.

別忘加上關鍵字 #WMAQ，並持續鎖定本週最新影片