a flock of birds.

很多動物都喜歡集結成群

Many animals gather in large groups

這是自然界中最美妙的一件事

that are among the most wonderful spectacles

但是為什麼要成群結隊呢?

in the natural world.

最常見的說法是

But why do these groups form?

為了安全或方便狩獵, 又或者交配與繁殖,

The common answers include things like

以上的這些解釋,

seeking safety in numbers or hunting in packs

通常都是正確的,

or gathering to mate or breed,

這些都是人類對於 動物們在行為上的假設

and all of these explanations,

這些動物們可以控制牠們的行為

while often true,

並對自己的身體負責

make a huge assumption about animal behavior,

但是通常卻不是這麼一回事

that the animals are in control of their own actions,

這是豐年蝦 (鹵蟲), 一種鹽水蝦

that they are in charge of their bodies.

又常被稱之為 ”海猴子“

And that is often not the case.

牠非常的小, 通常習慣獨居

This is Artemia, a brine shrimp.

但是牠也可以集結成 像這一大片的紅色群體

You probably know it better as a sea monkey.

大到足以用公尺(米)為單位來計算

It's small, and it typically lives alone,

這些豐年蝦之所以聚集,是因為寄生蟲

but it can gather in these large red swarms

這些蝦子都被 “絛蟲” 給感染了

that span for meters,

絛蟲 (寄生蟲) 實際上就像是 一條既長又活生生的腸子

and these form because of a parasite.

一端是生殖器, 另一端是帶鉤的口腔

These shrimp are infected with a tapeworm.

身為一個自由的撰稿人, 我很同情牠

A tapeworm is effectively a long, living gut

(群眾笑聲)

with genitals at one end and a hooked mouth at the other.

絛蟲吸附在豐年蝦的身上 並吸取牠的養分,

As a freelance journalist, I sympathize.

不止這樣, 絛蟲還做了另外一件事

(Laughter)

絛蟲閹割了這些豐年蝦

The tapeworm drains nutrients from Artemia's body,

絛蟲把這些豐年蝦從本身的 透明色轉變成了亮紅色,

but it also does other things.

絛蟲讓這些豐年蝦活得更久,

It castrates them,

生物學家尼可拉斯.羅得發現

it changes their color from transparent to bright red,

寄生的絛蟲讓這些 原本獨居的蝦集結在一起

it makes them live longer,

為什麼呢? 因為這些絛蟲 就像是其他的寄生物種一樣,

and as biologist Nicolas Rode has found,

有著複雜的生活形態

it makes them swim in groups.

擁有很多不同的宿主

Why? Because the tapeworm, like many other parasites,

寄生在這些蝦身上只是 這些絛蟲旅程的第一步

has a complicated life cycle

牠們的最終目的是這個,

involving many different hosts.

大紅鶴

The shrimp are just one step on its journey.

只有在紅鶴身上, 這些絛蟲才得以繁衍

Its ultimate destination is this,

所以為了要達到目的, 絛蟲只能先行操縱蝦子宿主

the greater flamingo.

進而形成這些顯眼的紅色蝦群

Only in a flamingo can the tapeworm reproduce,

這樣才能更輕易地吸引紅鶴的注意

so to get there, it manipulates its shrimp hosts

並獵捕吞食,

into forming these conspicuous colored swarms

而這就是豐年蝦群集的秘密.

that are easier for a flamingo to spot

豐年蝦並不是依 自身意志組成的群居動物

and to devour,

而是因為豐年蝦被控制了

and that is the secret of the Artemia swarm.

群體生活看似無法提供安全感

They aren't sociable through their own volition,

實際上卻剛好相反

but because they are being controlled.

絛蟲入侵了這些 豐年蝦的大腦與身體,

It's not safety in numbers.

並把這些豐年蝦當作

It's actually the exact opposite.

進入紅鶴體內的一項交通工具

The tapeworm hijacks their brains and their bodies,

這裡還有另外一個

turning them into vehicles

寄生蟲操縱宿主的案例

for getting itself into a flamingo.

這是一隻具自殺傾向的蟋蟀

And here is another example

這隻蟋蟀吞食了鐵線蟲的幼蟲,

of a parasitic manipulation.

鐵線蟲又名馬鬃蟲

This is a suicidal cricket.

蟲子會在蟋蟀身體裡長到成蟲,

This cricket swallowed the larvae of a Gordian worm,

但是牠(鐵線蟲)必須在水裡交配,

or horsehair worm.

當鐵線蟲需要交配時 就會分泌特殊蛋白質

The worm grew to adult size within it,

腐蝕蟋蟀的大腦,

but it needs to get into water in order to mate,

造成蟋蟀行為失常.

and it does that by releasing proteins

當蟋蟀靠近水邊的時候,

that addle the cricket's brain,

例如這個游泳池邊,

causing it to behave erratically.

牠就會跳入水裡並淹死自己,

When the cricket nears a body of water,

這時鐵線蟲就會

such as this swimming pool,

從死屍裡蠕動而出.

it jumps in and drowns,

蟋蟀體內很寬敞. 但是誰知道呢?

and the worm wriggles out

絛蟲和鐵線蟲並不孤單

of its suicidal corpse.

牠們是控制大腦的

Crickets are really roomy. Who knew?

寄生蟲軍團的一份子

The tapeworm and the Gordian worm are not alone.

像是真菌, 病毒, 蠕蟲, 昆蟲等等

They are part of an entire cavalcade

這些都是擅長攪亂及重寫

of mind-controlling parasites,

宿主們本身意願的寄生體

of fungi, viruses, and worms and insects and more

當我約20年前第一次

that all specialize in subverting and overriding

從大衛·阿滕伯勒的書 《生命的征途》上

the wills of their hosts.

學習到這種生物形態

Now, I first learned about this way of life

再從另一本非常好的書

through David Attenborough's "Trials of Life"

由我朋友卡爾·齊默 撰寫的《霸王寄生蟲》上見到

about 20 years ago,

之後我就以這些生物 為主題不停地寫作至今

and then later through a wonderful book called

還有一些生物學的主題令我更加著迷

"Parasite Rex" by my friend Carl Zimmer.

這感覺就像是這些 寄生蟲已經竄改了我的大腦

And I've been writing about these creatures ever since.

因為畢竟, 牠們是如此地引人注目

Few topics in biology enthrall me more.

卻又同時令人感到毛骨悚然

It's like the parasites have subverted my own brain.

當你在寫關於寄生蟲的文章時,

Because after all, they are always compelling

你的詞彙量張嘴就是 "活活吞噬"

and they are delightfully macabre.

閉口就是 “衝出身體”。

When you write about parasites,

(群眾笑聲)

your lexicon swells with phrases like

不僅如此

"devoured alive" and "bursts out of its body."

我是個作家, 觀眾席裡有些人也是作家

(Laughter)

作家都知道每個人都喜歡故事

But there's more to it than that.

寄生蟲讓我們拒絕撰寫那些

I'm a writer, and fellow writers in the audience

淺顯易見的故事情節的誘惑

will know that we love stories.

牠們生存的世界是劇情的轉折點之一

Parasites invite us to resist the allure

也是無法預測的解釋

of obvious stories.

為什麼? 例如,

Their world is one of plot twists

這隻毛毛蟲

and unexpected explanations.

當其他昆蟲靠近牠

Why, for example,

和那些白色蟲繭的時候

does this caterpillar

毛毛蟲是在開始激烈反抗嗎？

start violently thrashing about

毛毛蟲貌似在站崗護衛這些繭

when another insect gets close to it

難道毛毛蟲在保護牠的兄弟姐妹嗎?

and those white cocoons that it seems

不是的

to be standing guard over?

這隻毛毛蟲是被寄生蜂給攻擊

Is it maybe protecting its siblings?

並被體內產卵

No.

寄生蜂的蛋將孵化在 毛毛蟲的體內,

This caterpillar was attacked

而這隻寄生蜂幼蟲 在衝破毛毛蟲的身體之前

by a parasitic wasp which laid eggs inside it.

將毛毛蟲從內部活活吞食

The eggs hatched and the young wasps

你們了解我的意思了嗎?

devoured the caterpillar alive

然而, 這隻毛毛蟲還在苟延殘喘

before bursting out of its body.

有些寄生蜂卻背後

See what I mean?

控制著這只毛毛蟲

Now, the caterpillar didn't die.

保護自己的兄弟姐妹

Some of the wasps seemed to stay behind

直到牠們在繭內破繭成蟲

and controlled it into defending their siblings

這隻毛毛蟲只是一隻 搖頭晃腦的殭屍保鏢

which are metamorphosing

保護著那些殺死自己的

into adults within those cocoons.

生物的後代(寄生蜂的後代)

This caterpillar is a head-banging zombie bodyguard

(群眾掌聲)

defending the offspring

我們還有很多要說, 而我只有13分鐘 (群眾笑聲)

of the creature that killed it.

現在, 你們有些人可能

(Applause)

只是拼命地尋求一些慰藉

We have a lot to get through. I only have 13 minutes. (Laughter)

說這些都只是自然界裡的怪事,

Now, some of you are probably just

這些發生的事情都是離群值,

desperately clawing for some solace

這些論點都是可被理解的,

in the idea that these things are oddities

因為牠們的天性, 寄生體是很小的

of the natural world, that they are outliers,

牠們花費很多的時間

and that point of view is understandable,

在別的物種身上

because by their nature, parasites are quite small

牠們很容易被小看,

and they spend a lot of their time

但是這不代表牠們不重要

inside the bodies of other things.

幾年前, 有個名叫凱文·拉弗蒂的人

They're easy to overlook,

帶了一群科學家去了加州的三個河口

but that doesn't mean that they aren't important.

他們幾乎將能找到的所有東西

A few years back, a man called Kevin Lafferty

通通稱重, 解剖, 及記錄了下來,

took a group of scientists into three Californian estuaries

他們發現

and they pretty much weighed and dissected

寄生物種非常豐富多元

and recorded everything they could find,

尤其是吸蟲類最為常見,

and what they found

牠們(吸蟲)是專門閹割宿主的微小蠕蟲

were parasites in extreme abundance.

好比這隻不幸的蝸牛

Especially common were trematodes,

現在, 單一隻吸蟲是十分微小的, 僅能依靠顯微鏡觀測

tiny worms that specialize in castrating their hosts

但是全體加起來的重量就和

like this unfortunate snail.

河口裡所有的魚一樣重

Now, a single trematode is tiny, microscopic,

或者是所有鳥類總重的三到九倍之多

but collectively they weighed as much

還記得我剛才給你們看的鐵線蟲

as all the fish in the estuaries

和那隻蟋蟀嗎?

and three to nine times more than all the birds.

有個名叫佐藤拓也的日本科學家

And remember the Gordian worm that I showed you,

在一段河流裡發現

the cricket thing?

這些寄生蟲控制著很多的蟋蟀

One Japanese scientist called Takuya Sato

和蚱蜢跳入水中

found that in one stream,

進而淹死這些昆蟲

these things drive so many crickets

而這些昆蟲占了當地鱒魚60%的食物來源

and grasshoppers into the water

這些操控並不是奇怪的事

that the drowned insects

這是發生在我們週遭, 很複雜

make up some 60 percent of the diet of local trout.

卻又平常的世界的一部份

Manipulation is not an oddity.

科學家目前發現了

It is a critical and common part

數百種這類型的案例,

of the world around us,

更令人振奮的是, 科學家們開始了解

and scientists have now found

這些寄生體到底是 怎麼控制牠們宿主的

hundreds of examples of such manipulators,

這是我最喜歡的案例之一

and more excitingly, they're starting to understand

這是安瓿牛鞭

exactly how these creatures control their hosts.

也叫扁頭泥蜂

And this is one of my favorite examples.

還有件眾所皆知的事

This is Ampulex compressa,

就是這些扁頭泥蜂

the emerald cockroach wasp,

會自己的卵

and it is a truth universally acknowledged

產在蟑螂的身上

that an emerald cockroach wasp in possession

當牠(扁頭泥蜂)找到一隻(蟑螂)時

of some fertilized eggs

牠(扁頭泥蜂)用牠的刺來叮螫蟑螂

must be in want of a cockroach.

而刺同時也是牠的感覺器官

When she finds one,

這些都是三個禮拜前的新發現

she stabs it with a stinger

牠(扁頭泥蜂)的刺, 也就是牠的感覺器官

that is also a sense organ.

有著細小的感官突起物

This discovery came out three weeks ago.

這些突起物可以讓牠感受到

She stabs it with a stinger that is a sense organ

蟑螂大腦組織的特殊質地

equipped with small sensory bumps

就像是一個人盲目的 在一個袋子裡尋找,

that allow her to feel the distinctive texture

當扁頭泥蜂找到大腦時, 會將毒液注進

of a roach's brain.

兩種特定的神經元叢

So like a person blindly rooting about in a bag,

以色列的科學家, 弗雷德里克.李伯賽及拉姆.加爾

she finds the brain, and she injects it with venom

發現這些毒液是一種特定的化學武器

into two very specific clusters of neurons.

這種毒液並不會殺死蟑螂, 也不會對蟑螂產生鎮靜效果

Israeli scientists Frederic Libersat and Ram Gal

蟑螂還是可以離開

found that the venom is a very specific chemical weapon.

或是飛走, 如果蟑螂可以決定的話

It doesn't kill the roach, nor does it sedate it.

但是其實蟑螂並不能真正做這個決定,

The roach could walk away

因為這些毒液阻斷了蟑螂的行動意願

or fly or run if it chose to,

而也就只是這樣

but it doesn't choose to,

基本上這些蜂類讓蟑螂

because the venom nixes its motivation to walk,

喪失了逃生本能,

and only that.

讓扁頭泥蜂帶著無助的受害者(蟑螂)

The wasp basically un-checks the escape-from-danger box

藉由觸角回到巢穴內

in the roach's operating system,

就像是人在遛著狗一樣

allowing her to lead her helpless victim

再重複一次, 牠將蛋產在蟑螂上,

back to her lair by its antennae

蛋孵化, 幼蟲將蟑螂活活吞食, 再從牠身體裡破出,

like a person walking a dog.

如此之類的, 你們已經知道過程了

And once there, she lays an egg on it,

(群眾笑聲, 掌聲)

egg hatches, devoured alive, bursts out of body,

現在我認為, 一次叮螫後

yadda yadda yadda, you know the drill.

蟑螂不再是一隻蟑螂

(Laughter) (Applause)

而是泥蜂的延伸體,

Now I would argue that, once stung,

就像是蟋蟀是鐵線蟲的延伸體一樣

the cockroach isn't a roach anymore.

這些宿主失去了生存及生育的權利

It's more of an extension of the wasp,

牠們對於自身命運的掌控

just like the cricket was an extension of the Gordian worm.

如同我順利掌控我的車一樣.

These hosts won't get to survive or reproduce.

一旦寄生體侵入時,

They have as much control over their own fates

宿主便失去了發言權

as my car.

當然, 現在的人類

Once the parasites get in,

對操控並不陌生

the hosts don't get a say.

我們吸毒來改變大腦的化學物質

Now humans, of course,

和改變我們的情緒,

are no stranger to manipulation.

我們如果沒有打算 要影響別人的意志

We take drugs to shift the chemistries of our brains

那所謂的論點、廣告 又或者是偉大的構想又是什麼

and to change our moods,

但是我們所做的這些嘗試

and what are arguments or advertising or big ideas

和寄生蟲這種精密又特異的生物比較

if not an attempt to influence someone else's mind?

顯得十分粗糙、亂來

But our attempts at doing this

好比唐.德雷珀只希望他和

are crude and blundering compared

扁頭泥蜂一樣這麼的高貴和準確

to the fine-grained specificity of the parasites.

我認為這是寄生體之所以

Don Draper only wishes he was as elegant

如此邪惡又卻引人注目的部分原因

and precise as the emerald cockroach wasp.

我們相當注重我們的自由意志

Now, I think this is part of what makes parasites

和我們的自主權

so sinister and so compelling.

當我們失去這些特質後

We place such a premium on our free will

將會有看不見的力量

and our independence

將我們最深的社會恐懼呈現出來

that the prospect of losing those qualities

奧威爾的 “反烏托邦”和 “影子陰謀”

to forces unseen

還有控制大腦的超級惡棍們

informs many of our deepest societal fears.

都彷彿是暗黑小說中會出現的比喻,

Orwellian dystopias and shadowy cabals

但是卻無時無刻地 真實發生在自然界中

and mind-controlling supervillains --

這將我帶到一個明顯

these are tropes that fill our darkest fiction,

又令人不安的問題上:

but in nature, they happen all the time.

是否有一些陰險的寄生蟲

Which leads me to an obvious

在我們毫不知情的情況下

and disquieting question:

影響著我們的日常行為——

Are there dark, sinister parasites

除了國家安全局(NSA)?

that are influencing our behavior

如果有的話--

without us knowing about it,

(群眾笑聲, 掌聲)

besides the NSA?

我現在額頭上是不是多了個紅點? (被當成了靶)

If there are any —

(群眾笑聲)

(Laughter) (Applause)

如果有的話, 這樣會是牠們很好的候選人

I've got a red dot on my forehead now, don't I?

這是弓型蟲又稱弓漿蟲, 簡稱為弓蟲

(Laughter)

這麼叫牠

If there are any, this is a good candidate for them.

是因為令人害怕的物種 通常都有可愛的暱稱

This is Toxoplasma gondii, or Toxo, for short,

弓蟲會感染哺乳類動物,

because the terrifying creature

各個品種的哺乳動物,

always deserves a cute nickname.

但是牠(弓蟲)卻只能在 貓的身體裡進行有性繁殖

Toxo infects mammals,

科學家像是喬安妮.韋伯斯特證明了

a wide variety of mammals,

一旦弓蟲進入鼠類當中,

but it can only sexually reproduce in a cat.

將會把這些被感染的鼠類 化作尋找貓咪的導彈

And scientists like Joanne Webster have shown that

如果被感染的鼠類聞到了

if Toxo gets into a rat or a mouse,

貓咪尿液這樣吸引人的味道

it turns the rodent into a cat-seeking missile.

牠(鼠類)就會反常的奔往這味道的方向

If the infected rat smells the delightful odor

而不是一如往常地逃離

of cat piss,

當這些貓吃了這些鼠類, 弓蟲就得以完成交配

it runs towards the source of the smell

這就像是經典的故事模式：吃, 祈禱, 和愛

rather than the more sensible direction of away.

(群眾笑聲, 掌聲)

The cat eats the rat. Toxo gets to have sex.

你們是非常寬容又慷慨的人

It's a classic tale of Eat, Prey, Love.

嗨, 伊麗莎白, 我喜歡你的演說

(Laughter) (Applause)

寄生蟲是用什麼方法

You're very charitable, generous people.

控制著牠的宿主們?

Hi, Elizabeth, I loved your talk.

我們其實不是很知道原因

How does the parasite control its host

我們知道弓蟲會釋放某種酶

in this way?

製造多巴胺, 一種活化 大腦獎賞機制及創造動力

We don't really know.

的神經傳導物質

We know that Toxo releases an enzyme

我們知道牠(弓蟲)的目標是 囓齒動物大腦的特定部份,

that makes dopamine, a substance involved

包括喚起性慾的部分

in reward and motivation.

但是卻不清楚這些片段的認知