The biology of gender, from DNA to the brain | Karissa Sanbonmatsu

譯者: Lilian Chiu 審譯者: SF Huang

So what does it mean to be a woman?

身為女性是什麼意思？

We all have XX chromosomes, right?

我們都有 XX 染色體，對吧？

Actually, that's not true.

其實，並不是如此。

Some women are mosaics.

有些女性像是鑲嵌畫。

They have a mix of chromosome types with X, with XY or with XXX.

她們的染色體類型是有 X、 XY 或 XXX 的混合型態。

If it's not just about our chromosomes,

如果身為女性的重點 並不只在染色體，

then what is being a woman about?

那是什麼？

Being feminine?

女性化？

Getting married?

結婚？

Having kids?

生子？

You don't have to look far to find fantastic exceptions

這些規則都有例外，

to these rules,

且並不難找，

but we all share something that makes us women.

但某些共通性形塑我們成為女人。

Maybe that something is in our brains.

也許那種共通性存在我們的大腦中。

You might have heard theories from last century

你可能有聽過上個世紀所提的

about how men are better at math than women

男性比女性更擅長數學的理論，

because they have bigger brains.

因為男性的大腦比較大。

These theories have been debunked.

這些理論已經被推翻。

The average man has a brain about three times smaller

男人的腦袋比大象的腦袋

than the average elephant,

小約三倍，

but that doesn't mean

但那並不表示

the average man is three times dumber than an elephant ...

一般男人比大象笨三倍……

or does it?

或確實是如此呢？

(Laughter)

（笑聲）

There's a new wave of female neuroscientists

新一波的女性神經科學家

that are finding important differences between female and male brains

正研究出女性和男性的大腦間

in neuron connectivity,

在神經元的連接上、

in brain structure, in brain activity.

大腦結構上和大腦活動上的重大差異。

They're finding that the brain is like a patchwork mosaic --

她們發現，大腦就像 拼布鑲嵌圖一樣——

a mixture.

是種混合體。

Women have mostly female patches and a few male patches.

女性具有大部分的女性拼布 和一些的男性拼布。

With all this new data, what does it mean to be a woman?

有了這些新資料， 身為女性的意義是什麼？

This is something that I've been thinking about almost my entire life.

我幾乎一生都在想這個問題。

When people learn that I'm a woman who happens to be transgender,

人們發現我正好是跨性別的女性時，

they always ask,

他們總是會問：

"How do you know you're a woman?"

「妳怎麼知道妳是女性？」

As a scientist, I'm searching for a biological basis of gender.

身為科學家，我在尋找的是 性別的生物基礎。

I want to understand what makes me me.

我想要知道是什麼形塑了如今的我。

New discoveries at the front edge of science

科學前端的新發現，

are shedding light on the biomarkers that define gender.

為性別生物標記的領域開啟了曙光。

My colleagues and I in genetics, neuroscience, physiology and psychology,

我同事和我研究遺傳學、

神經科學、生理學和心理學，

we're trying to figure out exactly how gender works.

我們試圖了解性別是如何運作的 。

These vastly different fields share a common connection --

這些迥異的領域有一個共同的連結—

epigenetics.

表觀遺傳學。

In epigenetics, we're studying how DNA activity

在表觀遺傳學中，我們研究的是

DNA 的活動如何產生 徹底、永久的改變，

can actually radically and permanently change,

even though the sequence stays the same.

即使它的序列維持不變。

DNA is the long, string-like molecule that winds up inside our cells.

DNA 是纏繞在我們 細胞裡面的長型線狀分子。

There's so much DNA

DNA 的數量如此眾多， 以致像打結似地纏繞著——

that it actually gets tangled into these knot-like things --

we'll just call them knots.

我們就直接稱為「結」。

So external factors change how those DNA knots are formed.

外部因子會改變 這些 DNA 結的形成方式。

You can think of it like this:

你可以這樣想：

inside our cells, there's different contraptions building things,

在我們的細胞中，有不同的新奇裝置

在建構東西、連結線路、

connecting circuits,

doing all the things they need to make life happen.

執行維持生命運作所需的工作。

Here's one that's sort of reading the DNA and making RNA.

這個是在讀取 DNA 並製造 RNA。

And then this one is carrying a huge sac of neurotransmitters

而這個是將一個大型的神經傳遞質，

from one end of the brain cell

從大腦細胞的一端帶到另一端。

to the other.

Don't they get hazard pay for this kind of work?

它們做這種工作沒領安全津貼嗎？

(Laughter)

（笑聲）

This one is an entire molecular factory --

這個是完整的分子工廠——

some say it's the secret to life.

有些人說，它是生命的秘密。 它叫做核醣體。

It's call the ribosome.

I've been studying this since 2001.

我從 2001 年起就在研究這些。

One of the stunning things about our cells

我們的細胞其中一項 讓人吃驚的特性就是

is that the components inside them are actually biodegradable.

它們內部的組件是可行生物分解的。

They dissolve,

它們會溶解，

and then they're rebuilt each day,

每天又會再重建，

kind of like a traveling carnival

有一點像巡迴的遊樂場，

where the rides are taken down and then rebuilt every single day.

遊樂設施每天都會拆下來、 又重新搭建起來。

A big difference between our cells and the traveling carnival

我們的細胞和遊樂場最大的差別

is that in the carnival,

是在遊樂場中，

there are skilled craftsmen that rebuild the rides each day.

有技術精良的工匠 負責每天的重建工作。

In our cells, there are no such skilled craftsmen,

在我們的細胞中，沒有這種工匠，

only dumb builder machines

只有傻呼呼的建造機器，

that build whatever's written in the plans,

計畫寫什麼，它們就建什麼，

no matter what those plans say.

不管那些計畫說的是什麼。

Those plans are the DNA.

那些計畫就是 DNA。

The instructions for every nook and cranny inside our cells.

在細胞內部有著鉅細靡遺的指示。

If everything in, say, our brain cells

以我們的腦細胞為例， 如果裡面的一切

dissolves almost every day,

幾乎每天都會溶解，

then how can the brain remember anything past one day?

那大腦怎麼可能記得 前一天的任何事？

That's where DNA comes in.

那就是 DNA 上場的時候了。

DNA is one of the those things that does not dissolve.

DNA 是不會溶解的東西之一。

But for DNA to remember that something happened,

但若要 DNA 記住發生過什麼事，

it has to change somehow.

它就得做某種改變。

We know the change can't be in the sequence;

我們知道改變並不在序列中；

if it changed sequence all the time,

如果它隨時在改變序列，

then we might be growing like, a new ear or a new eyeball every single day.

那我們每天可能會長出 一個新耳朵或一顆新眼球。

(Laughter)

（笑聲）

So, instead it changes shape,

所以，它就改變自己的形狀，

and that's where those DNA knots come in.

這就是 DNA 結發揮作用的時候了。

You can think of them like DNA memory.

你可以把它們想成是 DNA 記憶。

When something big in our life happens,

當我們的人生中發生重大的事，

like a traumatic childhood event,

比如創傷性的兒時事件，

stress hormones flood our brain.

壓力荷爾蒙就會湧入我們的大腦。

The stress hormones don't affect the sequence of DNA,

壓力荷爾蒙不會影響 DNA 序列，

but they do change the shape.

但會改變它們的形狀。

They affect that part of DNA

它們透過指示減壓分子機器的啟動，

with the instructions for molecular machines that reduce stress.

影響那個部分的DNA。

That piece of DNA gets wound up into a knot,

那一段的 DNA 會繞成一個結，

and now the dumb builder machines can't read the plans they need

所以，傻呼呼的建造機器就無法讀到

它們需要建立減壓機器的計畫了。

to build the machines that reduce stress.

That's a mouthful, but it's what's happening on the microscale.

聽起來很冗長，但在 微觀世界的狀況就是這樣。

On the macroscale, you practically lose the ability to deal with stress,

宏觀上，你可能就會 失去處理壓力的能力，

and that's bad.

那不是好事。

And that's how DNA can remember what happens in the past.

那就是 DNA 記住過去 發生了什麼事的方式。

This is what I think was happening to me

我認為這就是我剛開始

when I first started my gender transition.

做性別轉變時發生的情況。

I knew I was a woman on the inside,

我知道我內在是位女性，

and I wore women's clothes on the outside,

外在會穿著女性的服飾，

but everyone saw me as a man in a dress.

但大家看到的都是 一位穿著女裝的男人。

I felt like no matter how many things I try,

我覺得，

不論我做多少嘗試，

no one would ever really see me as a woman.

都不會有人把我當作女性來看待。

In science, your credibility is everything,

在科學界，可信度凌駕一切，

and people were snickering in the hallways,

而大家會在走廊上竊笑，

giving me stares,

盯著我看，

looks of disgust --

做出嫌惡的表情——

afraid to be near me.

害怕靠近我。

I remember my first big talk after transition.

我記得我變性之後的 第一場大型演講。

It was in Italy.

地點在義大利。

I'd given prestigious talks before,

我之前做過不少頗具盛譽的演講，

but this one, I was terrified.

但這次，我害怕極了。

I looked out into the audience,

我看向觀眾，

and the whispers started --

開始有人耳語——

the stares,

還有人盯著看，

the smirks, the chuckles.

有假笑、有竊笑。

To this day, I still have social anxiety around my experience eight years ago.

至今，我仍因八年前的 這段經驗而患有社交恐懼症。

I lost hope.

我失去了希望。

Don't worry, I've had therapy so I'm OK --

別擔心，我有接受治療， 所以我沒事——

I'm OK now.

我現在沒事了。

(Laughter)

（笑聲）

(Cheers)

（歡呼）

(Applause)

（掌聲）

But I felt enough is enough:

但我受夠了，該適可而止了：

I'm a scientist,

我是科學家，

I have a doctorate in astrophysics,

我有天體物理學博士學位， 在頂尖期刊中發表過文章，

I've published in the top journals,

in wave-particle interactions, space physics,

研究領域包括波粒子交互作用、

nucleic acid biochemistry.

太空物理、核酸生物化學。

I've actually been trained to get to the bottom of things, so --

我受的專業訓練是要追根究柢，

(Laughter)

所以——

（笑聲）我上了網路——

I went online --

(Applause)

（掌聲）

So I went online, and I found fascinating research papers.

我上網，找到了很棒的研究論文。

I learned that these DNA knot things are not always bad.

我發現這些 DNA 結 並不一定都是不好的。

Actually, the knotting and unknotting --

其實，形成結和解開結——

it's like a complicated computer language.

就像是一種複雜的電腦語言。

It programs our bodies with exquisite precision.

它以細緻的精確度在我們體內運作。

So when we get pregnant,

所以，當我們懷孕時，

our fertilized eggs grow into newborn babies.

受精的卵子會長成新生兒。

This process requires thousands of DNA decisions to happen.

這個過程需要數千個 DNA 決策才能完成。

Should an embryo cell become a blood cell?

這個胚胎細胞應該變成血液細胞嗎？

A heart cell? A brain cell?

或是心臟細胞？腦細胞？

And the decisions happen at different times during pregnancy.

這些決策發生在懷孕的不同時期。

Some in the first trimester, some in the second trimester

有些是在前三個月， 有些是在四到六個月，

and some in the third trimester.

有些則在七到九個月。

To truly understand DNA decision-making,

若要真正了解 DNA 的決策方式，

we need to see the process of knot formation in atomic detail.

我們需要從原子細節 去了解結形成的過程。

Even the most powerful microscopes can't see this.

就連最強大的顯微鏡也看不到。

What if we tried to simulate these on a computer?

如果我們嘗試用電腦來做模擬呢？

For that we'd need a million computers to do that.

我們需要一百萬台電腦才辦得到。

That's exactly what we have at Los Alamos Labs --

我們在洛斯阿拉莫斯 國家實驗室正好就有——

a million computers connected in a giant warehouse.

在一間巨型的倉庫中， 有一百萬台電腦連結在一起。

So here we're showing the DNA making up an entire gene

這裡，我們展示的是 構成完整基因的 DNA

folded into very specific shapes of knots.

所形成特定形狀的結。

For the first time,

這是第一次，

my team has simulated an entire gene of DNA --

我的團隊模擬出了 整個基因的 DNA ——

the largest biomolecular simulation performed to date.

這是至今進行過 最大的生物分子模擬。

For the first time, we're beginning to understand the unsolved problem

這是第一次，我們解開了

of how hormones trigger the formation of these knots.

荷爾蒙如何觸發形成這些結的謎團。

DNA knot formation can be seen beautifully in calico cats.

DNA 結的形態在花斑貓的 身上完美展現出表徵。

The decision between orange and black

初期在子宮內，橘色和黑色的選擇

happens early on in the womb,

已然定調，

so that orange-and-black patchy pattern,

所以那橘黑相間的花樣，

it's an exact readout of what happened

正是精確地演繹出

when that cat was just a tiny little kitten embryo

小貓在母貓子宮的 胚胎時所定調的事而已。

inside her mom's womb.

And the patchy pattern actually happens in our brains and in cancer.

在我們的大腦以及癌症上，

也會看到花樣模式的情況。

It's directly related to intellectual disability and breast cancer.

它和智能障礙及乳癌有直接的關係。

These DNA decisions also happen in other parts of the body.

這些 DNA 決策也發生在 身體的其他部分。

It turns out that the precursor genitals transform into either female or male

結果發現，在懷孕的前三個月，

前驅生殖器會轉變成女性或男性。

during the first trimester of pregnancy.

The precursor brains, on the other hand,

另一方面，前驅大腦

transform into female or male during the second trimester of pregnancy.

是在懷孕的四到六個月 才會轉變成女性或男性。

So the current working model

所以，目前的工作模型是：

is that a unique mix in my mom's womb

在我母親子宮中的獨特組合機制，

caused the precursor genitals to transform one way,

造成前驅生殖器 以一種方式轉變性別，

but the precursor brain to transform the other way.

但前驅大腦 則以另一種方式轉變性別。

Most of epigenetic research

大部分的表觀遺傳學研究

has really focused on stress, anxiety, depression --

都把焦點放在壓力、焦慮、憂鬱——

kind of a downer,

蠻掃興的，都是壞事。

kind of bad things.

(Laughter)

（笑聲）

But nowadays --

但，現今，最新的東西——

the latest stuff --

大家在思考的是放鬆。

people are looking at relaxation.

Can that have a positive effect on your DNA?

放鬆對於你的 DNA 會有正面的影響嗎？

Right now we're missing key data from mice models.

現在，我們的老鼠模型 還缺少了關鍵性的資料。

We know that mice relax,

我們知道老鼠會放鬆，

but could they meditate like the Dalai Lama?

但，牠們能像達賴喇嘛那樣冥想嗎？

Achieve enlightenment?

得到啟發？

Could they move stones with their mind like Jedi Master Yoda?

牠們能像絕地武士尤達那樣 用念力移動石頭嗎？

(Yoda voice): Hm, a Jedi mouse must feel the force flow, hm.

（尤達的聲音）：嗯，絕地老鼠 必須要感受到原力的流動，嗯。

(Laughter)

（笑聲）

(Applause)

（掌聲）

I wonder if the support I've had since that talk back in Italy

我很納悶，從義大利的 那次演說之後，

我所得到的支持是否 在試著解開我的 DNA。

has tried to unwind my DNA.

Having a great circle of friends, supportive parents

很棒的朋友圈、很支持的雙親，

and being in a loving relationship

且沉浸在愛情之中，

has actually given me strength and hope to help others.

已經給了我力量與希望去幫助他人。

At work I wear a rainbow bracelet.

工作時我會戴著彩虹手環。

Sometimes it raises eyebrows, but it also raises awareness.

有時它會引人注目， 但它也會揚起意識。

There's so many transgender people --

有好多變性人——

especially women of color --

特別是有色人種的女性——

that are just one demeaning comment away from taking their own lives.

僅再一次貶低的詆毀， 就可能讓她們自殺。

Forty percent of us attempt suicide.

我們當中有四成的人嘗試過自殺。

If you're listening and you feel like you have no other option,

如果你在聽，

且你覺得別無選擇，

try to call a friend,

試著打電話給一個朋友，

go online or try to get in a support group.

上網或是去尋求支持團體。

If you're a woman who's not transgender but you know pain of isolation,

如果你是女性，不是變性人

但知道孤立的痛苦，

of sexual assault --

知道性侵的痛苦——

reach out.

請向外求援。

So what does it mean to be a woman?

所以，身為女性是什麼意思？

The latest research is showing

最新的研究顯示，

that female and male brains do develop differently in the womb,

女性和男性的大腦 在子宮內發展的方式確實不同，

possibly giving us females this innate sense of being a woman.

可能會給予我們女性這種 從內心就覺得自己是女人的感受。

On the other hand,

另一方面，

maybe it's our shared sense of commonality that makes us women.

也許是我們共有的 共通感讓我們成為女性。

We come in so many different shapes and sizes

我們有各種體型、尺寸，

that asking what it means to be a woman may not be the right question.

「身為女性是什麼意思」 可能不是個正確的問題。

It's like asking a calico cat what it means to be a calico cat.

這就像是問花斑貓， 身為花斑貓是什麼意思。

Maybe becoming a woman means accepting ourselves

也許，變成女性就表示

接受我們真實的自己，

for who we really are

and acknowledging the same in each other.

並認可彼此的共同性。

I see you.

我看見你們。

And you've just seen me.

你們也看見了我。

(Applause and cheers)

（掌聲及歡呼）