A herd of wildebeests, a shoal of fish, a flock of birds.
一群角马，一群鱼，一群鸟。
Many animals gather in large groups that are among the most wonderful spectacles in the natural world.
许多动物群居生活，那些都是大自然中最令人惊叹的奇观。
But why do these groups form?
但是为什么形成这些群落？
The common answers include things like seeking safety in numbers or hunting in packs or gathering to mate or breed,
通常的说法包括获得安全，或者方便捕猎，或者聚集交配繁殖，
and all of these explanations, while often true, make a huge assumption about animal behavior,
这些所有解释虽然通常正确，但对动物行为做出了一个重要假设，
that the animals are in control of their own actions, that they are in charge of their bodies. And that is often not the case.
那就是动物掌控它们的行为，并掌控它们的身体。但是通常事实并不是这样。
This is Artemia, a brine shrimp. You probably know it better as a sea monkey.
这是卤虫，一种盐水虾。你们也许更通常地称它为海猴子。
It's small, and it typically lives alone, but it can gather in these large red swarms that span for meters, and these form because of a parasite.
它很小，典型的独居类型，但是它可以聚集在这些大的红色群落中，其范围可达数米，这些的产生是因为一种寄生虫。
These shrimp are infected with a tapeworm.
这些虾子被一种绦虫寄生了。
A tapeworm is effectively a long, living gut with genitals at one end and a hooked mouth at the other.
绦虫实际上是一条长长的活着的肠子，它一端是生殖器，另一端是钩状的嘴。
As a freelance journalist, I sympathize.
作为一个自由撰稿人，我对它感到同情。
The tapeworm drains nutrients from Artemia's body, but it also does other things.
绦虫从卤虫的体内摄取养分，但它也做别的事情。
It castrates them, it changes their color from transparent to bright red, it makes them live longer,
它阉割卤虫，它将卤虫从透明变为赤红色，它延长卤虫的寿命，
and as biologist Nicolas Rode has found, it makes them swim in groups.
就像考古学家尼古拉斯·罗德所发现的，绦虫让它们成群出没。
Why? Because the tapeworm, like many other parasites, has a complicated life cycle involving many different hosts.
为什么呢？因为绦虫像很多别的寄生虫一样，有着复杂的生命周期，其中包括不同的寄主。
The shrimp are just one step on its journey. Its ultimate destination is this, the greater flamingo.
这些虾子只是它们旅程中的一步。它们最终的目标是更大的红鹳。
Only in a flamingo can the tapeworm reproduce, so to get there,
绦虫只有在红鹳体内才可以繁殖，所以为了去那里，
it manipulates its shrimp hosts into forming these conspicuous colored swarms that are easier for a flamingo to spot and to devour,
它操纵虾子寄主们，形成这些显眼的有色群落，让红鹳更容去发现并吞食，
and that is the secret of the Artemia swarm. They aren't sociable through their own volition, but because they are being controlled.
这就是卤虫群的秘密。他们不是因为自身意志而聚集起来的，而是因为被操纵。
It's not safety in numbers. It's actually the exact opposite.
这不是用大数量去获得安全。恰恰相反。
The tapeworm hijacks their brains and their bodies, turning them into vehicles for getting itself into a flamingo.
这些绦虫劫持了卤虫们的大脑和身体，把它们变成交通工具，以便于让它们进入到一只红鹳的体内。
And here is another example of a parasitic manipulation. This is a suicidal cricket.
这里有另外一个关于寄生操控的例子。这是一个自杀蟋蟀。
This cricket swallowed the larvae of a Gordian worm, or horsehair worm.
这只蟋蟀吞下了戈尔迪乌斯线虫或是马鬃虫的幼虫。
The worm grew to adult size within it, but it needs to get into water in order to mate,
虫子在蟋蟀体内长大成年，但是它需要到水中进行交配，为了完成繁殖，
and it does that by releasing proteins that addle the cricket's brain, causing it to behave erratically.
它通过释放一种扰乱蟋蟀大脑的蛋白质，使其行为不定。
When the cricket nears a body of water, such as this swimming pool, it jumps in and drowns,
当蟋蟀靠近水体时，例如这个游泳池，它会跳入并溺死，
and the worm wriggles out of its suicidal corpse. Crickets are really roomy. Who knew?
然后虫子从自杀蟋蟀尸体内蠕动出来。蟋蟀总是胸怀宽广。谁知道呢？
The tapeworm and the Gordian worm are not alone.
绦虫和毛细线虫并不孤单。
They are part of an entire cavalcade of mind-controlling parasites, of fungi, viruses,
它们是全部专于暗中破坏，压倒寄主意志，操控真菌、病毒、
and worms and insects and more that all specialize in subverting and overriding the wills of their hosts.
蠕虫、昆虫和更多其它生物的寄生虫中的一部分。
Now, I first learned about this way of life through David Attenborough's "Trials of Life" about 20 years ago,
在二十年前，我通过大卫·阿滕伯勒的纪录片《生命的审判》，首次了解到到关于这种生活方式，
and then later through a wonderful book called "Parasite Rex" by my friend Carl Zimmer.
之后通过我的朋友卡尔·基默写的一本叫做《寄生虫雷克斯》的书对其进一步了解。
And I've been writing about these creatures ever since. Few topics in biology enthrall me more.
从那时起我就一直在写关于这些生物。没有别的什么生物学话题能更让我着迷。
It's like the parasites have subverted my own brain.
这就像寄生虫已经颠覆了我的大脑。
Because after all, they are always compelling and they are delightfully macabre.
因为毕竟，它们总是在控制并且令人欣喜的毛骨肃然。
When you write about parasites, your lexicon swells with phrases like "devoured alive" and "bursts out of its body."
当你描写寄生虫时，你的用词里充满了这样的短语，“活活吞吃”和“从它的身体里炸出”。
But there's more to it than that. I'm a writer, and fellow writers in the audience will know that we love stories.
但是远远不止这些。我是一个作家，观众席中的作家同伙们知道我们热爱故事。
Parasites invite us to resist the allure of obvious stories. Their world is one of plot twists and unexpected explanations.
寄生虫使我们去排斥浅而易见的故事的诱惑。它们的世界充满着扭曲的情节和出人意料解释。
Why, for example, does this caterpillar start violently thrashing about when another insect gets close to it
举个例子，为什么这只毛毛虫，当另外一直昆虫靠近它时开始剧烈地颤动，
and those white cocoons that it seems to be standing guard over? Is it maybe protecting its siblings?
并且像那些白色茧的护卫一样？难道它在保护兄弟姐妹？
No. This caterpillar was attacked by a parasitic wasp which laid eggs inside it.
不对。这只毛毛虫受到了一只其在体内产卵的寄生蜂的攻击。
The eggs hatched and the young wasps devoured the caterpillar alive before bursting out of its body.
卵孵化后，幼蜂们将其活活地吞吃，再冲破其身体出来。
See what I mean? Now, the caterpillar didn't die.
现在知道（我之前）什么意思了吧？但是，毛毛虫没有死。
Some of the wasps seemed to stay behind and controlled it into defending their siblings which are metamorphosing into adults within those cocoons.
有些马蜂们留了下来，并继续控制毛毛虫去保护它们正在变态到成虫过程中茧内的兄弟姐妹们。
This caterpillar is a head-banging zombie bodyguard defending the offspring of the creature that killed it.
这只毛毛虫是一个保护着杀死它的生物的后代的甩头僵尸保镖。
We have a lot to get through. I only have 13 minutes.
我们还有很多要说。我只有13分钟。
Now, some of you are probably just desperately clawing for some solace in the idea that these things are oddities of the natural world,
现在，你们中有些人大概正因为这样的一些自然中的怪异的事物和局外者，
that they are outliers, and that point of view is understandable,
绝望地搜寻一些安慰，这个观点是可以理解的，
because by their nature, parasites are quite small and they spend a lot of their time inside the bodies of other things.
因为，寄生虫体型微小并且很大一部分时间生活在其他动物的体内。
They're easy to overlook, but that doesn't mean that they aren't important.
它们容易被忽略，但这不意味着它们不重要。
A few years back, a man called Kevin Lafferty took a group of scientists into three Californian estuaries
几年前，一个叫做凯文·拉弗蒂的人，带领一组科学家前往三个加州的河口，
and they pretty much weighed and dissected and recorded everything they could find, and what they found were parasites in extreme abundance.
它们基本上将所有发现的东西称重，解剖并记录，他们所发现的是寄生虫的数量极为巨大。
Especially common were trematodes, tiny worms that specialize in castrating their hosts like this unfortunate snail.
最常见的是吸虫，它们是小小的蠕虫，专阉割它们寄主，就像这只不幸的蜗牛。
Now, a single trematode is tiny, microscopic,
单单一条吸虫是小的，微观的，
but collectively they weighed as much as all the fish in the estuaries and three to nine times more than all the birds.
但是它们集合起来和河口中的鱼等重，并且是所有鸟重量的三至九倍。
And remember the Gordian worm that I showed you, the cricket thing?
还记得我之前向你们展示的戈尔迪乌斯线虫和那个蟋蟀么？
One Japanese scientist called Takuya Sato found that in one stream,
一位叫佐藤拓也的日本科学家在一条溪流中发现，
these things drive so many crickets and grasshoppers into the water that the drowned insects make up some 60 percent of the diet of local trout.
这些绦虫使这么多蟋蟀和蚱蜢淹死在水中，以至于为当地的鲤鱼提供了百分之六十的日常饮食。
Manipulation is not an oddity. It is a critical and common part of the world around us,
操控不是一种异常的现象。这是我们身边普遍并且至关重要的一部分，
and scientists have now found hundreds of examples of such manipulators,
科学家现在已近发现成百上千这样操控者的例子，
and more excitingly, they're starting to understand exactly how these creatures control their hosts.
更让人激动的是，他们开始去理解这些生物是具体是如何控制它们的寄主的。
And this is one of my favorite examples. This is Ampulex compressa, the emerald cockroach wasp,
这是我最喜欢的例子之一。这是扁头泥蜂，翡翠蟑螂蜂，
and it is a truth universally acknowledged that an emerald cockroach wasp in possession of some fertilized eggs must be in want of a cockroach.
载有受精卵的蟑螂蜂肯定需要一只蟑螂是一个被普遍接受的事实。
When she finds one, she stabs it with a stinger that is also a sense organ.
当蟑螂蜂找到一只蟑螂，她会用刺蛰蟑螂，那根刺又是一个感觉器官。
This discovery came out three weeks ago.
这个发现三周前才出来。

She stabs it with a stinger that is a sense organ equipped with small sensory bumps that allow her to feel the distinctive texture of a roach's brain.
她用具感觉器官的刺蛰蟑螂，这个器官上有着小的突起物，可以让蟑螂蜂感觉到蟑螂大脑中不同的质地。
So like a person blindly rooting about in a bag, she finds the brain,
就像一个人在袋子里盲目地乱摸，蟑螂蜂找到蟑螂的大脑，
and she injects it with venom into two very specific clusters of neurons.
将毒液注射到两簇非常具体的神经元中。
Israeli scientists Frederic Libersat and Ram Gal found that the venom is a very specific chemical weapon.
以色列科学家弗雷德里克·拉波塞特和莱姆·加尔发现，这个毒液是一种非常特别的化学武器。
It doesn't kill the roach, nor does it sedate it.
它不会杀死蟑螂，也不会让其昏昏欲睡。
The roach could walk away or fly or run if it chose to, but it doesn't choose to,
蟑螂如果想的话，可以选择走开，飞走或跑开，但是它没有选择这样做，
because the venom nixes its motivation to walk, and only that.
因为那个毒液使其丧失了走的意愿，只是那样。
The wasp basically un-checks the escape-from-danger box in the roach's operating system,
蟑螂蜂大体上关闭了蟑螂神经系统中逃避危险的本能，
allowing her to lead her helpless victim back to her lair by its antennae like a person walking a dog.
让蟑螂蜂能够借助蟑螂的触角，领着她无助的受害者回到她巢穴，就像一个人遛狗一样。
And once there, she lays an egg on it, egg hatches, devoured alive, bursts out of body, yadda yadda yadda, you know the drill.
蟑螂一到那里，蟑螂蜂就在其体内产一个卵，卵孵化了，幼虫将蟑螂活生生吞吃，并从其身体中迸发出来，吧啦吧啦叭啦叭啦，你们知道的。
Now I would argue that, once stung, the cockroach isn't a roach anymore.
我认为，蟑螂一旦被刺，它就不再是一只蟑螂了。
It's more of an extension of the wasp, just like the cricket was an extension of the Gordian worm.
它更像是蟑螂蜂的一个延伸体，就像蟋蟀是戈尔迪乌斯线虫的延伸体一样。
These hosts won't get to survive or reproduce. They have as much control over their own fates as my car.
这些寄主们不能生存和繁殖。它们对命运的掌握就像我的车的命运被我掌握一样。
Once the parasites get in, the hosts don't get a say.
一旦寄生虫进入其体内，寄主就失去了发言权。
Now humans, of course, are no stranger to manipulation.
当然人类对于操控并不陌生。
We take drugs to shift the chemistries of our brains and to change our moods,
我们用药物移动我们大脑中的化学物质去改变我们的心情，
and what are arguments or advertising or big ideas if not an attempt to influence someone else's mind?
有什么辩论或者广告或者伟大的想法，不企图去影响其他人的思想呢？
But our attempts at doing this are crude and blundering compared to the fine-grained specificity of the parasites.
但是我们对其的尝试，和那些寄生虫天衣无缝的专一性相比是不成熟的。
Don Draper only wishes he was as elegant and precise as the emerald cockroach wasp.
唐·德雷珀只是希望他可以像翡翠蟑螂蜂一样优雅和精确。
Now, I think this is part of what makes parasites so sinister and so compelling.
我认为这是让寄生虫如此险恶并如此引人注意一部分原因。
We place such a premium on our free will and our independence
我们如此珍视我们的自由意志和独立，
that the prospect of losing those qualities to forces unseen informs many of our deepest societal fears.
以至于我们在不可见力下失去那些品质的可能性，揭示了许多我们最深处的社会恐慌。
Orwellian dystopias and shadowy cabals and mind-controlling supervillains
奥威尔反乌托邦作品，神出鬼没的阴谋组织和会大脑操控的超级恶棍，
these are tropes that fill our darkest fiction, but in nature, they happen all the time.
这些都是充斥着我们邪恶小说中的比喻，但是在自然中，它们无时无刻不在发生。
Which leads me to an obvious and disquieting question:
这让我提出了一个明显又令人不安的问题：
Are there dark, sinister parasites that are influencing our behavior without us knowing about it, besides the NSA?
除了美国国家安全局，还有没有邪恶的寄生虫在我们不知道的情况下影响着我们的行为？
If there are any -- I've got a red dot on my forehead now, don't I?
如果有的话...现在估计有人想把我灭了吧？
If there are any, this is a good candidate for them.
如果有，这是一个非常好的候选人。
This is Toxoplasma gondii, or Toxo, for short, because the terrifying creature always deserves a cute nickname.
这是弓形虫，简称弓虫，令人毛骨悚然的生物总是值得有一个可爱的名字。
Toxo infects mammals, a wide variety of mammals, but it can only sexually reproduce in a cat.
弓虫会感染哺乳类动物，各种各样哺乳动物，但是它只可以在猫体内有性繁殖。
And scientists like Joanne Webster have shown that if Toxo gets into a rat or a mouse,
像乔安妮·韦伯斯特这样的科学家已经证明了，如果弓虫进入到老鼠体内，
it turns the rodent into a cat-seeking missile.
它会将这个捏齿类动物变成寻猫导弹。
If the infected rat smells the delightful odor of cat piss,
如果被感染的老鼠问到了美妙的猫尿的味道，
it runs towards the source of the smell rather than the more sensible direction of away.
它就会跑向那气味的发源地，而不是聪明的逃跑。
The cat eats the rat. Toxo gets to have sex. It's a classic tale of Eat, Prey, Love.
猫吃了老鼠。弓虫去交配。这是饮食，猎物和爱情之间的经典故事。
You're very charitable, generous people. Hi, Elizabeth, I loved your talk.
你们都是善良慷慨的人啊。嗨，伊丽莎白，我很喜欢你的演讲。
How does the parasite control its host in this way? We don't really know.
寄生虫是怎样在这种方式下操纵其寄主的？我不真正了解。
We know that Toxo releases an enzyme that makes dopamine, a substance involved in reward and motivation.
但我们知道弓虫释放一种酶，这种酶制造一种涉及奖励与动机的物质--多巴胺。
We know it targets certain parts of a rodent's brain, including those involved in sexual arousal.
我们知道这种酶把老鼠大脑中特定的部分作为目标，包括那些涉及性冲动部分。
But how those puzzle pieces fit together is not immediately clear.
但这些拼图的碎片是怎样拼在一起的现在还不是很清楚。
What is clear is that this thing is a single cell. This has no nervous system.
清楚的是，弓虫是单细胞生物。它没有神经系统。
It has no consciousness. It doesn't even have a body. But it's manipulating a mammal? We are mammals.
它没有意识。它甚至连一个身体都没有。但是它却在操控一只哺乳动物？我们都是哺乳动物。
We are more intelligent than a mere rat, to be sure, but our brains have the same basic structure,
毫无疑问，我们比老鼠更加智慧，但是我们大脑有着相同的基础构造，
the same types of cells, the same chemicals running through them, and the same parasites.
同类型的细胞，同样的在其中穿梭的化学物质，以及同样的寄生虫。
Estimates vary a lot, but some figures suggest that one in three people around the world have Toxo in their brains.
（对其的）推测各不相同，但数据显示，全世界三分之一的人大脑里有弓虫。
Now typically, this doesn't lead to any overt illness.
很典型的是，它们不会导致任何显性病症。
The parasite holds up in a dormant state for a long period of time.
寄生虫在很长的一段时间里保持休眠状态。
But there's some evidence that those people who are carriers score slightly differently on personality questionnaires than other people,
但是有一些证据显示，那些是寄生虫载体的人在性格调查问卷中和其他人得分略有不同，
that they have a slightly higher risk of car accidents,
他们有稍微高一些车祸风险，
and there's some evidence that people with schizophrenia are more likely to be infected.
有些证据显示精神分裂症的人更容易被感染。
Now, I think this evidence is still inconclusive, and even among Toxo researchers,
我认为这个证据是没有什么结果的，而且在弓虫的调查人员之间，
opinion is divided as to whether the parasite is truly influencing our behavior.
对于是否寄生虫真正影响我们的行为存在着争议。
But given the widespread nature of such manipulations,
但鉴于这种操控的普遍性，
it would be completely implausible for humans to be the only species that weren't similarly affected.
人类作为唯一没有相同症状的物种是难以置信的。
And I think that this capacity to constantly subvert our way of thinking about the world makes parasites amazing.
我认为这种能够颠覆我们对这个世界思想方式的能力，让寄生虫十分迷人。
They're constantly inviting us to look at the natural world sideways,
它们不停地使我们从侧面去看大自然，
and to ask if the behaviors we're seeing, whether they're simple and obvious or baffling and puzzling,
并使我们去质疑所目睹的行为，无论它们是简单明了，还是令人费解的，
are not the results of individuals acting through their own accord but because they are being bent to the control of something else.
是否不是我们我们按照自己意愿去行动的结果，而是因为它们被歪曲进而去控制别的东西的结果。
And while that idea may be disquieting, and while parasites' habits may be very grisly,
当这个想法令人不安时，当寄生虫的行为冷人毛骨悚然时，
I think that ability to surprise us makes them as wonderful and as charismatic as any panda or butterfly or dolphin.
我想那个让我们惊讶的能力使它们像任何熊猫，蝴蝶，或是海豚一样美好和有魅力。
At the end of "On the Origin of Species," Charles Darwin writes about the grandeur of life, and of endless forms most beautiful and most wonderful,
在“关于物种起源”的结尾，查尔斯·达尔文写到了关于生命的辉煌和无尽的最美丽的、最美好的形态的辉煌。
and I like to think he could easily have been talking about a tapeworm that makes shrimp sociable or a wasp that takes cockroaches for walks.
我认为，他很有可能在说让虾子社会化的绦虫，或者是带着蟑螂散步的马蜂。
But perhaps, that's just a parasite talking. Thank you.
但是，也许我所说的只是被寄生虫操控的结果罢了。谢谢。