经济学人下载:进化意外造就的杀手(2)

From this predator's point of view the requirement to evolve resistance to a venom, particularly one that is not lethal, is therefore low.
从这种捕食者的角度来看，对进化出毒液抵抗力（尤其是非致命毒液）的要求因而很低。

The spider's interests, too, may be served by the evolution of non-lethal venom.
非致命毒液的进化可能也符合蜘蛛的利益。

A live predator that has learnt not to attack may be better than a dead one,
一只学会不攻击的捕食者可能比一只已死捕食者更好，

which might then be replaced by a conspecific which has not learned that lesson.
因为后者可能会被一个没有学会这一教训的同种掠食者所取代。

This is particularly true when the venom is directed towards animals that teach their young,
尤其是当动物们拿毒液来教育它们的幼崽，

as many mammals do, about what is and is not dangerous in the world.
就像哺乳动物一样，教会它们世界上的危险与安全。

Get stung by a bee and you will surely advise your children to give bees a wide berth, even though bees are not predators.
被蜜蜂蛰了，你肯定会建议你的孩子离蜜蜂远点，即使蜜蜂不是捕食者。

To pursue this idea, Dr Fry and his colleagues looked at the genetic sequences describing 22 types of delta-hexatoxin,
为了证实这个想法，Fry博士和他的同时观察了22种类型的delta-hexatoxin基因序列，

extracted from ten species of funnel-webs. This let them analyse the peptides' evolutionary histories.
提取自十种漏斗网蜘蛛。这让他们能够分析出多肽的进化历史。

Funnel-web spiders are an ancient group, believed to have emerged about 150m years ago, near the end of the Jurassic period.
漏斗网蜘蛛是一个古老的种群，据信出现于1.5亿年前，接近侏罗纪末期。

Dr Fry's analysis suggested that, around that time, delta-hexatoxin peptides were evolving rapidly, but have subsequently barely changed.
Fry博士的分析表明，在那时候，delta-hexatoxin多肽进化迅速，但之后几乎没有改变。

This is consistent with the idea that they were evolving into something which would discourage, but not kill,
这与一种观点是一致的，即它们进化成了一种能够阻止，但不会杀死

vertebrate predators such as mammals—a group that also appeared in the late Jurassic.
哺乳动物等脊椎动物捕食者的生物——这个种群也出现在侏罗纪晚期。

Which is all well and good, but does not explain why funnel-web delta-hexatoxins are so deadly to people.
这一切都很好，但并不能解释为什么漏斗网delta-hexatoxins对人类如此致命。

The answer to this, Dr Fry suspects, is that until the arrival in Australia 65,000 years ago of human beings,
Fry博士认为这是因为，直到65000年前人类到达澳大利亚，

funnel-web spiders had never encountered primates (of which that continent has no wild representatives)
漏斗网蜘蛛还从未遇到过灵长类动物（该大陆没有这种动物的野生代表），

and so had had no chance to co-evolve with them. In one sense, then, the fact funnel-web delta-hexatoxins are lethal to humans
因此没有机会与它们共同进化。在某种意义上，漏斗网delta-hexatoxins对人类致命这一事实

is indeed an unlucky accident caused by some quirk of primate biochemistry not shared with other groups of mammals.
确实是一个不幸的意外，是由灵长类动物生物化学中与其他哺乳动物不同的某些怪癖引起的。

But if such co-evolution had taken place, it would have been in the interests of both sides for this lethality, too, to have been whittled away.
但如果发生这种共同进化，削弱其致命性也符合双方的利益。