万物简史 第497期:多灾多难的生命进程(17)

 What all this leaves us with, as one researcher has put it, is "tons of conjecture¹ and very little evidence." 这一切留给我们的，正如一位研究人员所说，“是大量的猜测和很少的证据”。

Cooling seems to be associated with at least three of the big extinction² events — the Ordovician, Devonian, and Permian, 变冷似乎至少与三次大灭绝事件有关——奥陶纪事件、泥盆纪事件和二叠纪事件，

but beyond that little is agreed, including whether a particular episode happened swiftly or slowly. 但是，除此以外，大家几乎没有共识，包括某次事件是快速发生的还是缓慢发生的。

Scientists can't agree, for instance, whether the late Devonian extinction — the event that was followed by vertebrates moving onto the land, 比如，泥盆纪灭绝事件——那个事件以后，脊椎动物迁移到了陆地，

happened over millions of years or thousands of years or in one lively day. 是在几百万年里发生的，还是在几千年里发生的，还是在热热闹闹的一天里发生的，科学家们的看法不一。

One of the reasons it is so hard to produce convincing explanations for extinctions is that it is so very hard to exterminate³ life on a grand scale. 对灭绝提出令人信服的解释的难度如此之大，原因之一是要大规模灭绝生命是非常困难的。

As we have seen from the Manson impact, you can receive a ferocious⁴ blow and still stage a full, if presumably somewhat wobbly, recovery. 我们从曼森撞击事件中已经看到。你可能受到猛烈的一击，但仍可以充分恢复过来，虽然觉得有点挺不住。

So why, out of all the thousands of impacts Earth has endured, was the KT event so singularly devastating⁵? 因此，地球已经忍受了几千次撞击。为什么偏偏6500万年前的KT事件的破坏性那么大，足以使恐龙遭受灭顶之灾呢？

Well, first it was positively⁶ enormous. 哎呀，首先，它确实厉害。

It struck with the force of 100 million megatons. Such an outburst is not easily imagined, but as James Lawrence Powell has pointed⁷ out, 它的撞击力达到1亿亿吨。这样的爆炸是术容易想像的，但正如詹姆斯·劳伦斯指出的，

if you exploded one Hiroshima-sized bomb for every person alive on earth today you would still be about a billion bombs short of the size of the KT impact. 要是你朝今天地球上的每个活人爆炸一颗广岛型原子弹，你离KT撞击事件的威力仍相差大约10亿颗这类炸弹。

But even that alone may not have been enough to wipe out 70 percent of Earth's life, dinosaurs⁸ included. 然而，仅此一项也许仍不足以消灭地球上70%的生命，包括恐龙在内。

 

1 conjecture   

n./v.推测，猜测

参考例句：

• She felt it no use to conjecture his motives.她觉得猜想他的动机是没有用的。
• This conjecture is not supported by any real evidence.这种推测未被任何确切的证据所证实。

2 extinction   

n.熄灭，消亡，消灭，灭绝，绝种

参考例句：

• The plant is now in danger of extinction.这种植物现在有绝种的危险。
• The island's way of life is doomed to extinction.这个岛上的生活方式注定要消失。

3 exterminate   

v.扑灭，消灭，根绝

参考例句：

• Some people exterminate garden insects by spraying poison on the plants.有些人在植物上喷撒毒剂以杀死花园内的昆虫。
• Woodpeckers can exterminate insect pests hiding in trees.啄木鸟能消灭躲在树里的害虫。

4 ferocious   

adj.凶猛的，残暴的，极度的，十分强烈的

参考例句：

• The ferocious winds seemed about to tear the ship to pieces.狂风仿佛要把船撕成碎片似的。
• The ferocious panther is chasing a rabbit.那只凶猛的豹子正追赶一只兔子。

5 devastating   

adj.毁灭性的，令人震惊的，强有力的

参考例句：

• It is the most devastating storm in 20 years.这是20年来破坏性最大的风暴。
• Affairs do have a devastating effect on marriages.婚外情确实会对婚姻造成毁灭性的影响。

6 positively   

adv.明确地，断然，坚决地；实在，确实

参考例句：

• She was positively glowing with happiness.她满脸幸福。
• The weather was positively poisonous.这天气着实讨厌。

7 pointed   

adj.尖的，直截了当的

参考例句：

• He gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。
• She wished to show Mrs.John Dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。

8 dinosaurs   

n.恐龙( dinosaur的名词复数 )；守旧落伍的人，过时落后的东西

参考例句：

• The brontosaurus was one of the largest of all dinosaurs. 雷龙是所有恐龙中最大的一种。 来自《简明英汉词典》
• Dinosaurs have been extinct for millions of years. 恐龙绝种已有几百万年了。 来自《简明英汉词典》