How does your brain fall in love?

當你墜入愛河時，你的大腦發生什麼事？

Is it something magical that happens to your brain,

是有神奇的魔法發生在你的大腦裡嗎？

or is there something biological that happens to your brain

還是生物學上的反應

that causes us to fall in love?

導致我們墜入愛河？

That was my question.

這是我的疑問

This is what we know about love:

這個圖是我們所知的愛

we know some neurotransmitters increase and some drop.

我們知道有些神經遞質會增加和減少

Your cortisol level, the stress hormone, increases causing you to feel nervous,

你的皮質醇，也就是壓力賀爾蒙增加時，會導致你感到緊張

while your oxytocin level increases causing you to feel amorous.

當你的催產素增加時，會讓你有戀愛的感覺

A woman's testosterone goes up causing her to be more aggressive,

女人的睪酮增加時，會使她較有衝勁、好鬥的

while a man's drops causing him to be more passive.

但男生的減少時，會使他變得較消極

And in both, their serotonin level drops causing them to be a little more obsessed.

而且不論男女，當他們的血清素下降時，他們會比較心神不寧

And, although we know what happens, we don't know how you get there.

雖然我們知道發生了什麼事，但我們不知道如何發生的

There are certain chemical processes happen,

這其中有化學反應的過程發生

including the tipping point, where you have an increase;

包括臨界點，就是使你的激素開始上升的地方

and also an enzymatic reaction, where you have a subsequent decrease.

還有酶促反應，就是你隨後下降的地方

Either of these would fit nicely into that missing section.

任何一個都可以將缺少的部分搭配得很好

So I was pondering this, and I just happened to be on vacation.

所以我深思這個變化，然後有一次我去度假

I was visiting my family,

拜訪我的親戚

and I have a cousin who is a PhD in biochemistry,

我有一個表哥，他是生物化學的博士

so I decided to use the opportunity to pick his brain.

所以我覺得藉由這個機會去請教他

I told him what I knew about love.

我告訴他據我所知的愛

I said, "Certain neurotransmitters go up, certain ones go down.

我說：「某些神經遞質上升，而某些神經遞質會下降

I think it may be biochemical."

我想這可能是生化反應。」

I looked at him, and he gave this expression of, "Plausible."

我看著他，然後他給我的回應是「似乎滿有道理的。」

I said, "Some may have a tipping point reaction."

我說：「有些人可能會有臨界點反應。」

He said, "Plausible," or looked plausible.

他說：「滿有道理的。」或是聽起來似乎有理

And then, I said, "Others may be enzymatic with a subsequent decrease."

然後我說：「其他有可能會有酶促反應隨後下降。」

Again, he gave me the facial expression of plausible.

他再次給我認同的表情

He's not a big talker, so I thought this was going really well.

他不是吹牛大王，所以我覺得事情進展得很順利

(Laughter)

(笑聲)

But before I could formulate my next question,

但在我說出下個問題前

my then 95-year-old grandmother spoke up, and she said,

我 95 歲的外婆說話了，她說：

"You, youngsters, don't know anything about love."

你們這些年輕人根本不懂什麼是愛

I was shocked, and I said, "Yeah, I know. That's why we're talking about this."

我很震驚，然後我說：「沒錯！這就是為什麼我們在討論這個問題。」

She said, "Your problem is you, young girls, jump into bed too quick.

她說：「問題在於你們這些小女孩，太快就發生性行為了。」

(Laughter)

(笑聲)

You fall in love, but a boy doesn't fall in love that way."

你戀愛了，但男生卻不會因此而墜入愛河

And I kind of looked at her, and I said,

我看著她，然後我說

"OK, let's talk a little bit more. How does a boy fall in love?"

「好，那我們再多說一點，要怎樣才能讓男生墜入愛河呢？」

And she said, "Back in my day, a girl knew

然後她說：「在我那個年代

if she wanted a boy to fall in love with her,

如果女生想要讓男生與她戀愛

she couldn't sleep with him right away."

她絕對不可以很快地和他發生性行為

Now, I had heard that stuff before: there was things like the three-date rule,

我曾聽過有個「三次約會的規定」

there's the 90-day rule from Steve Harvey's book,

還有「九十天的規定」，這些規定來自 Steve Harvey 的書

"Act like a lady, think like a man,"

「行為要像個女人，思想要像個男人。」

but I always thought those were anecdotal.

但我總是覺得那些都是傳聞

I didn't think there was any science behind it,

我不認為有任何科學根據

so I looked over at my cousin.

所以我看向我的表哥

His face no longer said plausible.

他的臉不再表示認同了

I decided to continue with my grandmother

我決定繼續跟我的外婆討論

because of the date; the question was the date.

因為約會，問題是約會

I said, "How long do you need to wait before you have sex?"

我說：「那要等多久才可以發生性行為？」

She says, "Ah, you wait to have sex until he falls in love."

她說：「啊！你必須等他有墜入愛河時才可以。」

"OK. Well, Granny, how do I know when he falls in love?"

「嗯…外婆，那我要怎麼知道他墜入愛河了呢？」

She says, "Oh, that's easy, you know he's in love when he commits."

她說：「那很簡單，當他給予承諾時就是戀愛了。」

I looked over at my cousin, and I was like, "What do you think?"

我看向我的表哥，暗示著：「你覺得呢？」

and he hung his head, and he just shook it.

他低頭了，然後只搖搖頭

(Laughter)

(笑聲)

He said, "OK, Granny, it's time to go home."

他說：「外婆，該回家了。」

I realized he was not buying any of this,

我明白他不認同外婆說的話

and my research had to continue on another day.

然後我的研究持續進行

I returned home, and I hit the research library.

我回到家，去研究圖書館查資料

The problem

問題是

is there's not a lot of research out on how humans fall in love,

沒有很多有關人類如何戀愛的研究

primarily, because of the way we do research.

主要是因為我們研究的方式

Imagine a guy saying, "Oh, I love you."

想像一個男人說：「喔！我愛你。」

He falls in love, and a researcher walks up saying,

他戀愛了，然後一個研究者向前說：

"Congratulations! Can I inject this into your brain to see if it has an effect?"

「恭喜你！可以讓我解析你的腦袋，看是否有任何影響嗎？」

You're not going to get many volunteers.

你不會找到很多自願的實驗者

So we had to rely on the next best thing: animal studies.

所以我們必須依賴其他方式：動物實驗

But what animals fall in love?

但是什麼動物會戀愛？

Well, we know when humans fall in love, they show exclusiveness to one person,

嗯 ... 我們知道人類會戀愛，他們會表現出對一個人的專情

so they started looking at other creatures that mated exclusively.

所以他們開始找其他是會完全交配的動物

And they ended up settling on these guys: the monogamous prairie vole.

最後他們設定實驗對象：一夫一妻的橙腹田鼠

When a prairie vole finds a mate that they're interested in,

當橙腹田鼠找到牠有興趣的伴侶時

they will, basically, mate for life.

基本上他們會終身相伴

So they started looking at the neurotransmitters

所以他們開始研究牠們的神經遞質

to see what was going on,

看看會發生什麼事

and what they discovered

然後他們發現

was one of the first things that increases is dopamine.

其中第一件事就是多巴胺會增加

And if they block the dopamine, they would lose the loving feeling.

如果他們阻斷多巴胺，牠們就會失去愛的感覺

So they thought, "Oh, dopamine," but they knew there was a problem.

所以他們認為「原來是多巴胺！」，但是他們發現有一個問題

Dopamine couldn't be it with human romantic love

多巴胺不能成為人類戀愛的原因

because dopamine goes up with a lot of things.

因為許多事情都會造成多巴胺增加

It goes up with gambling, chocolate, playing Candy Crush

像是賭博、巧克力或是玩《糖果傳奇》(線上遊戲)

(Laughter)

(笑聲)

so it couldn't possibly be dopamine.

所以不可能是多巴胺

So they said, "Well, we know there's another one

他們說：「我們知道有另一個

that's involved in bonding; it's called oxytocin."

也有相關，叫做催產素

And oxytocin goes up with mothers and children, that causes them to bond.

當媽媽和小孩之間的催產素增加，會讓他們連結在一起

So they said, "Let's take a look at that," so they looked at that.

所以他們說：「我們來研究這個看看。」，於是就開始觀察

They found that when a female finds a man she's interested in,

他們發現當女人對某個男人感到興趣時

her oxytocin goes up by 51%,

她的催產素高達 51%

and then if they block it, she loses that loving feeling.

然後如果他們阻斷催產素，她會失去愛的感覺

So they said, "Ah, it must be dopamine and oxytocin,"

所以他們說：「啊！一定是多巴胺和催產素造成的。」

but there was a problem.

但還是有個問題

It can't be oxytocin for a man, because of testosterone.

由於男人含有睪酮，催產素對男人不會造成影響

Testosterone blocks the effects of oxytocin.

睪酮會阻擋催產素的影響

So they said, "It's got to be something different."

所以他們說：「男女應該有些不同。」

They looked at another one that had a similar formula to oxytocin,

他們研究其他類似催產素配方的東西

and that is vasopressin.

那就是抗利尿激素

So they did the study again.

因此他們再次研究

The voles would meet. They'd have the vasopressin.

他們用田鼠實驗，牠們都有抗利尿激素

They'd inject an antagonist, a chemical block to the vasopressin;

他們注射了一種拮抗劑，那是一種化學成分阻止抗利尿激素增加

he would lose that loving feeling.

然後他失去愛的感覺

So they said, "Oh, then it's got to be dopamine and vasopressin for males,

他們認為：「多巴胺和抗利尿激素是影響男性戀愛的因素

and possibly some testosterone because we know that it goes up."

睪酮也可能有所影響，因為它也增加了。」

So they said, "Ah, perfect."

他們說：「沒錯，完美的解釋。」

What does that mean for us? Is this applicable?

這對我們來說意味著什麼？這是適用的嗎？

To find that out,

為了找出答案

I wrote to one of the Head of Studies at Florida State University, and I asked,

我寫了一封信詢問在佛羅里達州立大學的研究主任，我問他

"Is the vole study applicable to humans?"

「田鼠研究是否適用於人類呢？」

His response is a little embarrassing; he wrote back, "Of course, Dawn!"

他的回答有些尷尬，他回信：「當然可以！」

The exclamation point is his.

他堅決認為是可以的

I didn't want to write back for further clarification.

我不想再回信詢求更多的澄清

That was a little embarrassing, so I didn't have to.

這有點尷尬，所以我不需要這麼做

Fortunately for me, Tiffany Love, from the the University of Michigan,

幸運地，來自密歇根大學 Tiffany Love

came out publicly, and she said that she believed

公開說到她相信

that the vole studies and human romantic love were similar.

田鼠的戀愛研究和人類的戀愛是很相似的

So, great. Now what does that mean?

太棒了，這是什麼意思呢？

Well, if we look back at the mechanism, we can see that for females

如果我們回頭再看這個機制，我們可以看到女人戀愛時

that would mean dopamine increases and oxytocin increases.

多巴胺和催產素會增加

Dopamine increases when we're dating, when we're going to win;

當我們約會時、要贏的時候

we are excited: we're going to win the grand prize of love.

我們會很興奮：我們會贏得愛的大獎

As long as you're dating and you're happy, your dopamine is going up.

一旦你在約會和開心時，你的多巴胺就會增加

Oxytocin goes up; it's called the cuddle hormone, or the trust hormone,

催產素增加，被稱為擁抱賀爾蒙或信任賀爾蒙

so when you're kissing, cuddling, having a good time, oxytocin increases.

所以當你在親吻、擁抱或享受美好時光時，催產素會增加

And as you're dating a man and you're learning to trust him,

當你與一個男人約會，然後學著相信他時

your oxytocin increases.

你的催產素會增加

But there's a catch.

但有一個問題

Oxytocin slowly builds up that way, but it skyrockets at orgasm.

利用那種方式，催產素會增加得很慢，但它在高潮時會飆升

In other words, my grandmother might have been on to something.

換句話說，我的外婆可能已經知道了些什麼

Remember what she said?

還記得她說的嗎？

"You girls, jump into bed too quick; you fall in love."

「你們這些女孩太快發生性行為，就會墜入愛河。」

It was starting to look like

現在看來

the science was panning out from what my grandmother said.

科學研究的結果驗證了我外婆說的話

So I looked at the other part: how does a man fall in love?

所以我研究另一個部分：男人是怎麼戀愛的？

If we look at it, dopamine...

如果我們研究多巴胺 ...

If he is having a good time, his dopamine is going up,

如果他享受美好的時光，他的多巴胺會增加

but how does his vasopressin go up?

但他的睪酮是如何增加的呢？

Vasopressin goes up when a man is sexually stimulated.

當男人受到性刺激時，睪酮會增加

So if he's dating a woman he's sexually interested in,

所以如果他與他想發生性行為的女人約會時

the vasopressin increases.

睪酮會增加

But here's the catch:

但有一個問題

unlike oxytocin, vasopressin drops when he has sex.

當他發生性行為時，不像催產素，睪酮會開始下降

So how important is that?

所以這有多重要？

Well, I looked into it further; Florida State University ran a study,

我更進一步去研究，佛羅里達州立大學執行一項研究

and they said it's not just the neurotransmitters that are important.

他們認為不只是遞質神經很重要

You have to have the receptors. And how do you get the receptors?

你必須有受體，然後你如何有受體？

You get the receptors with the presence of the neurotransmitters.

你得到神經遞質存在的受體

Neurotransmitters tell your body to build the receptors,

神經遞質傳達訊息使你的身體建立受體

so you have to have the neurotransmitters high enough

所以你必須要有足夠的神經遞質

to build the receptors to, then, get them filled.

建立受體，然後讓它們充滿

So that means it takes some time.

也就是說這需要花一點時間

But there was one other thing my grandmother said, you remember?

但是有另一件事是我外婆說過的，你還記得嗎？

"You know a man's in love with you when he commits."

「當男人給予承諾時代表他深深愛上你了。」

Could commitment have anything to do with this?

承諾對我們有任何影響嗎？

To find that out, I found a study from the United States Air Force.

為了找出答案，我找到來自美國空軍的一個研究

The Air Force followed over 2,000 servicemen for more than a decade

十多年來，空軍追蹤了 2000 多名軍人

taking various tests.

給予他們多種測試

One of test that they took was for testosterone.

其中一個測試是關於睪酮

What they found is, when a guy comes in, and he is single,

他們發現當一個男人是單身時

his testosterone is relatively high, but as soon as he gets married, it drops.

他的睪酮相對高，但一旦他結婚了，它就會下降

Remember what I told you about testosterone?

還記得我說過關於睪酮的影響嗎？

It blocks the effects of oxytocin.

它會阻擋催產素的影響

Oxytocin is a bonding hormone,

催產素是一種結合賀爾蒙

so it was kind of looking like it could have something to do with it,

所以看起來它們都有相關

but it needed further clarification.

但還需要更多證明

Was it marriage? Was it actually commitment?

是婚姻造成的？還是承諾呢？

They did a study at Harvard University.

他們在哈佛大學做了個研究

They took married men, single men, and men in committed relationships.

他們找了已婚男人、單身男人和承諾關係的男人

They tested their testosterone.

他們測試他們的睪酮

This is what they discovered:

他們發現

like the Air Force study,

就像空軍研究

the single men had high testosterone,

單身男人有較高的睪酮

where the men that were married had lower testosterone.

而已婚男人則較低

And here's the catch: in the men that were married,

但這有個問題：已婚男人

and in the men that were in committed relationships,

和承諾關係的男人

the testosterone level did not differ.

睪酮含量並沒有不同

That means that the testosterone didn't drop when he got married,

也就是說當他結婚時，睪酮並沒有下降

it dropped prior, when he committed.

在他承諾時就已經下降了

So that means my grandmother looks like she was right.

所以也就證明我外婆說的似乎是正確的

Women take a bigger risk and tend to fall in love when she has sex,

女人在發生性行為時會冒更大的風險，往往會墜入愛河

and men tend to fall in love when he has commitment.

男人則是在承諾時才會墜入愛河

So that confirmed something for me that I'd always suspected,

所以這證實了一件我總是抱有懷疑的事情

not just that women tend to fall in love with sex

不只是女人性行為時墜入愛河

and men with commitment,

和男人承諾時墜入愛河

something even more important,

有件事比這些更重要

and that is: my grandmother is brilliant.

那就是：我的外婆太聰明了

(Laughter)

(笑聲)

(Applause)

(掌聲)