听力文摘：缓慢的生存（打印版）

Silkworms have been bred over thousands of years to behave quite unlike their caterpillarcousins in the wild.

蚕这种动物已经被人类豢养了上千年，这使得它们的行为远远异于野外的毛毛虫同类们。

That's because people purposely breed silkworms to fit this job description:

因为人类故意培养蚕，使得它们能够适应这样的工作岗位：

WANTED–Superlative silk producers.

诚聘：招优秀的产丝工。

Benefits include housing, unlimited food and protection fromall predators.

福利包括住房、包吃包喝、不受天敌威胁。

Wanderlust greatly discouraged. No opportunity for travel.

不欢迎旅游迷。没有出差机会。

Obviously, what makes a good silk producer in captivity is very different from what helps a caterpillar survive in the wild.

很明显，造就人工饲养的产丝能手的条件跟让野生毛毛虫在野外生存的能力会非常不同。

Commercial silkworms are dynamos at silk production, andcompared to their wild relatives, rather sluggish about everything else.

跟它们的野生同类相比，商用蚕在产丝方面是能手，但在其他任何方面的行动都很迟缓。

Outdoors, you've probably seen caterpillars crawling to find food or hide from birds, butcommercial silkworm caterpillars hardly move.

在户外，你可能见过毛毛虫爬来爬去寻找食物或躲避鸟类，但是商用蚕幼虫很少活动。

For silk production, they're kept on open traysbecause they're content to stay put, as long as they have a steady supply of mulberry leaves.

为了产丝，这些蚕就被放在敞口的匾上，因为只要有充足的桑叶供应，它们就会满足于一动不动地呆着。

Even when they reach the moth stage, commercial silkworms are surprisingly immobile.

即使商用蚕蜕变成蛾子，它们的活动力也惊人地弱。

Wildmoths fly to evade predators and to lay their eggs in different areas.

野生的蛾子会到处飞，以躲避天敌并且把卵产在不同的地方。

However, commercial silkworm moths haven't needed to do these things for thousands of years.

但是，从上千年前开始，商用蚕的蛾子就不用做这些事情了。

They've completelylost the ability to fly, even though they still have wings!

即使它们仍然有翅膀，它们也已对完全丧失了飞行的能力。

Here's another difference.

还有一处不同。

In the wild, moths are often very particular about where they'll lay eggs.

野外的蛾子通常对产卵地点很挑剔。

This ensures that baby caterpillars can chomp their favorite leaves as soon as they hatch.

这可以保证它们的幼虫一孵化就能吃到喜欢吃的树叶。

Commercial silkworm moths have lost that instinct too.

商用蚕的蛾子连这种本能也丧失了。

They'll even lay eggs on a sheet of paper,where it's easy for humans to keep track of them.

它们甚至会在纸张上产卵，对于人类来说可以很方便的找到它们。