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Imagine you're being attacked by a ferocious predator.
想象你被一只凶猛的捕食者攻击。
With no chance of escape, you do what any courageous, self-respecting possum would do:
在走投无路的情况下，你采取的行动将和任何勇敢、自爱的负鼠一样：
curl into an immobile state called catatonia, stick out your tongue, drool,
卷曲身躯，进入一种称为紧张症的静止状态，伸出舌头，流口水，
and ooze some foul-smelling liquid from your anal glands.
然后从肛门的分泌腺释放出难闻的体液。
Disgusted, your assailant loosens its grip, decides you're not the dinner it was looking for, and departs.
看见这个情况，深感恶心的攻击者松开它的爪子，意识到你并不是它所寻找的美味晚餐，最后离你而去。
After 10 minutes, you resurrect and merrily saunter on.
在十分钟后，你苏醒，然后愉快地继续漫步。
From lemurs to lizards, ants to amphibians, sharks to chickens, hundreds of animals "play dead" as a survival tactic.
从狐猴到蜥蜴，蚂蚁到两栖动物，鲨鱼到鸡，数以百计的动物都使用“装死”来作为它们的生存战略。
Nicknamed "playing possum" after its star performer, feigning death is also called thanatosis.
“模仿负鼠”是一个以负鼠命名的俗语，而装死在英语也叫“thanatosis”。
That's from Thanatos, the ancient Greek deity of death.
这个词源自于古希腊神话中的死神桑纳托斯。
But most scientists call it tonic immobility, or TI.
但是大多数科学家都称装死为“紧张性麻痹”，或者简称TI。
How and why TI occurs depends on the species and situation.
TI发生的原因和过程因物种品种和情况而异。
Spewing stench and adopting odd postures are common and often play important roles.
最常见和最重要的手法是释放恶臭味以及做古怪的姿势。
Other animals sacrifice their neighbors:
有些动物则选择牺牲邻近的同类：
quail chicks that freeze while their kin run amok have a better chance of survival when pursued by a cat.
当被猫追捕时，静止不动的雏鹌鹑比拼命逃命的有更高的生存率。
Speaking of cats, feline mothers can pinch the napes of their kittens' necks and induce another kind of immobility called clipnosis.
说到猫，母猫轻咬小猫的颈背可以引发另一种成为“夹子催眠”的麻痹现象。
This keeps their kittens quiet and easy to transport.
母猫这样做可以确保小猫在被移动时保持冷静。
Most of the physiological mechanisms underlying these theatrics originate in the parasympathetic nervous system,
导致这些现象的大多数生理机制源自于副交感神经系统，
better known for controlling cycles of resting and digesting.
它更广为人知是因为能控制休息和消化的周期。
In possums, the parasympathetic nervous system causes their heart rates to drop by nearly half,
对负鼠来说，副交感神经系统降低其心跳率接近一半，
respiration by a third, and body temperatures by more than half a degree Celsius for up to an hour.
其呼吸率接近三分之一，以及其体温约0.5摄氏度为期约一个小时。
The neurotransmitter dopamine also plays a part.
多巴胺这种神经传递素也起重要的作用。
Flour beetles with low dopamine levels play dead more frequently than those with high levels,
拥有较低多巴胺的面象虫比拥有较高多巴胺的更常装死，
and anything blocking dopamine receptor sites can lengthen catatonia.
此外，任何能够阻挡多巴胺感受器的物质可以延长紧张症。
But maintaining a death ruse isn't easy.
但是维持装死姿态并不容易。
The performers are constantly gauging their surroundings for cues on when it's safe to rise.
装死的生物必须时刻寻找线索来判断周围是否安全。
Chickens, for instance, can sense when a predator's eyes are upon them.
举个例子，鸡可以察觉掠食者是否正在注视着它们。
Researchers know this because when they used a stuffed hawk in an experiment,
研究人员知道这个事实，因为当他们使用老鹰标本来做实验时，
their chicken subjects came out of their catatonia quicker when the hawk's eyes were averted.
鸡会在假老鹰的眼睛转过去后更快地从紧张症中苏醒。
Other animals use TI for purposes other than defense.
除了防御，一些动物也使用TI做其他用途。
When the sleeper cichlid feels peckish, it sinks to the lake floor and lies motionless,
当非洲慈鲷感觉饥饿时，它就会沉下湖底并静止不动地躺着，
its splotchy coloration making it seem like a rotting carcass.
其身上的斑点让它看起来如同死尸。
If a small scavenger investigates, this undead trickster strikes.
如果小型的食腐动物接近检查时，这条不死的骗子将袭击它们。
Some animals even feign death as a sexual ploy.
一些动物更用装死为交配策略。
Male nursery spiders offer gifts of silk-wrapped insects in hopes of wooing females.
为了取悦雌盗蛛，雄盗蛛会把被蛛丝包裹的昆虫赠送给它们。
But those females are known to eat love-seeking males.
但是雌盗蛛也会吃掉寻爱的雄盗蛛。
By playing dead while the female eagerly devours her snack,
这些雄盗蛛会趁雌盗蛛享用礼品时装死，
these males can cautiously revive and improve their chances of successfully mating.
并谨慎地苏醒以提高它们交配的成功率。
So TI can work to an animal's advantage, unless someone else knows its secret.
所以TI对动物来说非常有利，不过其他动物也会用其来从中得益。
California orcas can flip over young great white sharks,
加利福尼亚虎鲸可以把年幼的大白鲨翻转过来，
inducing TI for so long the immobilized sharks, who must move to respire, essentially suffocate.
诱发鲨鱼的TI机制，导致必须不断游动来呼吸的鲨鱼因为长时间静止而窒息死亡。
Humans can also flip sharks into TI.
人类也可以把鲨鱼翻转过来诱发TI。
By stroking a shark's electrically-sensitive snout and gently turning it over,
通过不断抚摸鲨鱼对电力敏感的鼻口部，并轻轻地把它翻过来，
researchers can induce TI that lasts up to 15 minutes.
研究人员可以让长达15分钟的TI发生。
That's enough time to insert tags, remove hooks, and even perform surgeries.
这使得研究人员有足够的时间植入标签，移除鱼钩，甚至进行手术。
There are risks however: TI can hamper respiration and induce hyperglycemia, a sign of stress.
但这并非全无风险：TI可以影响呼吸以及导致高血糖--压力其中一个征兆。
So this technique should only be used when necessary.
所以这种手法应该只在必要时使用。
Humans can also experience TI when they freeze with fear during violent assaults.
人类也会经历TI，尤其是在面对暴力袭击时因恐惧而静止不动。
Recognizing this ancient, involuntary form of self-defense
对这古老、不由自主的自卫方法的认知，
has significant implications when trying to understand why some victims don't flee or fight in the face of danger.
可大大地帮助我们了解为什么一些受害者在面临危险时不逃跑或反击。
So, studying TI in non-human animals not only helps us better understand some odd behaviors,
所以，研究非人类动物的TI机制不只帮助我们更清楚地了解一些古怪的行为，
it can also help us better understand our own, sometimes counterintuitive, responses to violence.
也帮助我们更透彻地了解我们本身在面临暴力时有时违反直觉的反应。
