【TED演讲】斑马有条纹的原因出乎意料

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When an English aristocrat rode through London in a zebra-drawn carriage, he embodied a dream decades in the making,

当一位英国贵族乘坐斑马马车穿过伦敦时，他体现了一个几十年来

borne from European efforts to dominate the African continent.

欧洲人试图统治非洲大陆的梦想。

But 19th century European colonists faced big problems as they tried to control the sprawling African territories they'd claimed,

但是，19 世纪的欧洲殖民者在试图控制他们声称拥有的广阔非洲领土时面临着巨大的问题，

one of which was biting flies.

其中之一就是叮咬蝇。

These pests could extract half a liter of horse blood daily while transmitting fatal diseases that devastated domestic horses,

这些害虫每天可以吸取半升马血，同时传播致命的疾病，摧毁家养马，

leaving colonial powers reliant on thousands of humans to transport goods.

导致殖民列强依赖成千上万的人来运输货物。

Zebras, however, appeared immune to the same pitfalls as horses.

但是，斑马似乎不会像马一样，遇到同样的陷阱。

The German Empire deemed them "predestined for the use of military needs," and undertook the task of domesticating them.

德意志帝国认为它们“注定要用于军事需求”，并承担了驯养它们的任务。

Around 1900, former German colonial army officer Fritz Bronsart von Schellendorff placed himself at the mission's helm.

1900 年左右，前德国殖民军军官弗里茨·布朗萨特·冯·谢伦多夫担任了这项任务的负责人。

But he severely underestimated the project.

但是他严重低估了该项目。

And soon enough, the question of why domesticating zebras was proving so difficult joined another longstanding mystery: namely,

很快，为什么驯养斑马如此困难的问题就与另一个长期未解之谜联系在一起：

why zebras had such conspicuously striped coats— a matter that perplexed prominent scientists— and went on to fuel decades of debate.

为什么斑马的皮毛上有如此醒目的条纹——这个问题让著名科学家感到困惑——并继续引发了数十年的争论。

To understand zebras' more distinctive qualities, we should start with the big picture.

要了解斑马更独特的品质，我们应该从全局入手。

Zebras belong to the same family as horses and donkeys.

斑马与马和驴同属一科。

After their lineage entered Africa, they evolved into the three zebra species that exist today, living in social herds in eastern and southern Africa,

它们的血统进入非洲后，进化为现存的三种斑马物种，生活在非洲东部和南部的社会群体中，

grazing on grasses and evading fierce predators.

以草为食， 躲避凶猛的捕食者。

Scientists have speculated extensively about zebra striping, but not all theories have held up.

科学家们对斑马条纹进行了广泛的猜测，但并非所有理论都成立。

For example, the hypothesis that striping has a social function seems unlikely because, while every zebra does have unique patterning,

例如，条纹具有社会功能的假设似乎不太可能，因为尽管每只斑马都有独特的图案，

other equids have no trouble identifying individuals in their herd without it.

但其他马科动物即使没有条纹也可以毫不费力地识别群体中的个体。

Some have theorized that the pattern helps zebras stay cool in direct sunlight,

有人推测，这种图案有助于斑马在阳光直射下保持凉爽，

with the heat differential between their black and white stripes generating cooling air currents.

黑白条纹之间的热差会产生冷却气流。

But when scientists tracked the air movements around sunlit zebra hides, they saw no such effect.

但是，当科学家追踪阳光照射下的斑马皮周围的空气运动时，他们并没有看到这样的效果。

Many have also wondered if the patterning works as camouflage or somehow confuses or dazzles predators— perhaps evoking a tangle of tree trunks or creating uncertainty around where the zebra's body starts and ends.

许多人还想知道， 这种图案是否起到了伪装的作用，或者以某种方式迷惑或眩晕捕食者——也许是树干缠绕在一起，或者使其难以确定斑马身体的起点和终点。

But hyenas and lions probably see zebras as gray until they're in close range, where they can also hear and smell them.

但是鬣狗和狮子可能一直认为斑马是灰色的，直到它们靠近到能听到和闻到其味道的距离。

Lions can likely also identify their outlines just as easily as they can other, less flamboyantly patterned prey.

狮子也可能像识别其他不那么艳丽的猎物一样，轻易地识别它们的轮廓。

And given how frequently lions capture zebras, it doesn't seem like they're all that confused.

考虑到狮子捕捉斑马的频率，它们似乎并不那么困惑。

One hypothesis that does pack a lot of promise concerns those biting flies that horses couldn't handle.

一个确实很有希望的假设是，那些马无法对付的叮咬蝇。

Zebras have shorter hair than other grazers in their regions, possibly making them more vulnerable to the flies' probing proboscises.

斑马的毛发比所在区域的其他食草动物短，这可能使它们更容易受到叮咬蝇探查的喙的伤害。

So, perhaps striping somehow acts protectively.

因此，也许条纹在某种程度上起到了保护作用。

Testing this hypothesis, one experiment found that a certain kind of biting fly avoided horses covered in striped and checked rugs,

为验证这一假设，一项实验发现，与覆盖纯灰色地毯的马相比，

compared to those in solid grey.

某种叮咬蝇会避开覆盖条纹和格子地毯的马。

Another documented biting flies circling horses, zebras,

另一项记录表明，叮咬蝇在马、斑马

and horses clad in zebra print equally— but landing on zebra-y areas only about a quarter as much.

和穿着斑马纹的马身上盘旋的次数相同，但降落在斑马纹区域的次数只有大约四分之一。

Biting flies also generally approached zebras at higher speeds and didn't decelerate as usual, causing clumsy overshoots and crash landings.

叮咬蝇通常以更高的速度接近斑马，并且不会像往常一样减速，导致笨拙地超越并坠落。

It seems that zebra stripes— and other graphic patterns— interfere with how biting flies process visual information to position themselves when landing,

似乎斑马条纹和其他图案模式会干扰叮咬蝇处理视觉信息的方式，以确定着陆时的位置，

limiting their blood-sucking and disease-transmitting opportunities.

从而限制它们吸血和传播疾病的机会。

But zebras aren't just good at keeping biting flies off their backs.

而并不只是斑马擅长驱赶背上的苍蝇。

Around 1900, Bronsart founded an experimental ranch near Mount Kilimanjaro to capture and cross-breed zebras with other equids.

1900 年左右，布朗萨特在乞力马扎罗山附近建立了一个实验牧场，用于捕获斑马并将其与其他马科动物杂交。

Things didn't go as planned— in part because zebras have a robust set of defensive fight and flight adaptations.

事情没有按计划进行——部分原因是斑马有一套强大的防御性战斗和逃跑适应能力。

Most are capable of running within an hour of birth, and they're equipped with fierce bites and kicks strong enough to kill a lion.

大多数斑马在出生一小时侯就能奔跑，而且它们拥有凶猛的咬合力和踢腿力，足以杀死一只狮子。

Bronsart's operation was also unprepared to meet zebras' needs.

布朗萨特的行动也没有做好满足斑马需求的准备。

Those Bronsart did gather, which he paid Indigenous people to wrangle, couldn't produce enough milk for their calves.

布朗萨特确实获得了斑马，并付钱给土著人帮忙来饲养，因为这些斑马无法为幼崽提供足够的奶水。

Within a single year, Bronsart had burned through a five year budget and dozens of the zebras he held in captivity were dead.

仅仅一年时间，布朗萨特就花光了五年的预算，他圈养的数十只斑马都死了。

Attempts at zebra domestication had failed miserably, leaving those rare instances of zebra taming largely to black-and-white history.

驯养斑马的尝试惨遭失败，将那些罕见的斑马驯化事例，基本上只剩下黑白历史了。