考满分 toefl

1 .<-NARRATOR:->Listen to part of a lecture in an archaeology class.

旁白：请听下面一段考古学课堂上的讲解。

1 .<-FEMALE PROFESSOR:->Between 11,000 and 10,000 B.C.E., North America was populated by a wide variety of great beasts like mammoths and mastodons— both elephant-like creatures with big tusks— and camels, giant sloths… mm, the list goes on…

教授：在公元前 11000 年到 10000 年前，北美洲生活着各种大型的生物，比如猛犸和乳齿象（两种都是类似大象的动物，都有巨大的长牙），还有骆驼和大地懒等大型生物。

2 .By about 10,000 B.C.E., all those giant creatures, the megafauna of North America, were gone.

但是大约在公元前 10000年时，所有的巨型生物，北美的猛犸都消失了。

3 .Uh, we don’t know exactly what happened to them, but there are some theories.

我们不能确定到底发生了什么事情，但是对此有许多理论。

1 .One theory is that they were hunted to extinction by humans.

一种理论是说他们被人类猎杀以至于灭绝了。

2 .The humans who coexisted with these giant species in North America at that time were what we today call the Clovis people.

当时在北美洲与这些巨型生物同时存在的是我们现在所说的克洛维斯人。

1 .And there’s a Clovis site in a valley in Southern California where the remains of thirteen mammoths were found.

在南加利福尼亚的山谷中发现了一个克洛维斯遗址，这里发现了 13 只猛犸象的遗迹。

2 .And spear points, tools for processing meat, and fireplaces.

同时还发现了矛头，加工肉的工具和篝火。

3 .That would appear to be some pretty compelling evidence.

这看起来是十分令人信服的证据。

4 .Mammoth bones have also been found at some other Clovis sites…

在其他的克洛维斯遗址中也发现了猛犸象的骨头。

5 .But then, at other Clovis sites, uh, there’s also a lot of evidence that the Clovis people mostly gathered plants and hunted small game, like rabbits and wild turkeys…

但是在其他的克洛维斯遗址中，也有不少证据证明克罗维斯人大部分是以采集植物和猎杀小型动物为生，如兔子和野驴...

6 .Also, there are several places in North America where you have natural accumulations of mammoth bones— uh, that look very similar to the accumulations at the Clovis sites, except there’s no human debris— where the mammoths almost certainly died as the result of some kind of natural disaster…

而且在南美的一些地方还发现了许多自然聚集的猛犸象的骨头，看起来与克洛维斯遗址中的一样，只不过没有人类的遗迹，看起来猛犸象像是死于某种自然灾害。

7 .So I think it’s quite likely that those thirteen mammoths in Southern California also died of natural causes… and that the Clovis people simply took advantage of the situation.

所以我认为在南加利福尼亚克洛维斯遗址中发现的猛犸象也有可能是死于自然灾害，而克洛维斯人只是坐享渔翁之利。

1 .Um, OK, that’s the hunting theory.

嗯，这就是猎杀理论。

2 .Now let’s look at another theory— uh, an alternative to the hunting theory— the climate change theory.

现在我们来讨论另一个理论，这是猎杀理论的一个可替代理论，气候变化理论。

1 .At around 11,500 B.C.E., the world was coming out of an ice age.

在公元前 11500 年前，地球走出了冰河世纪。

2 .And with that came increased seasonality; that is, the summers became warmer and the winters actually became colder.

随之而来的是季节性的增加，夏天变得更加温暖，而冬天则变得更加寒冷。

3 .These extreme shifts would have put a lot of stress on the bodies of animals that were used to a more moderate range of temperatures.

这种极端的变化可能给一直处于气候变化不大的环境中的动物的身体带来了很大的压力。

4 .But the most important impact of this increased seasonality may very well have been its effect on the distribution of plants.

而季节性增加造成最大的冲击可能是对植物分布的影响。

5 .Today we take for granted that there are horizontal bands of plant communities: in the far north is tundra, which gives way to forest as you move southward, and even farther south, grasslands take over.

现在我们认为植物群体的水平分布理所当然，最北面是冻土带，接下来往南是森林带，而到了最南边是草原带。

6 .But during the ice age, these plant communities actually grew together, mixed with one another.

但是在冰河世纪，这些不同的植物实际上是长在一起的，相互融合。

7 .So ice-age animals had access to many different types of plants, different types of food.

所以冰河世纪的动物能够吃到不同的植物，各种各样的食物。

8 .But when the seasons became more distinct, the plant communities were pulled apart. That meant that in any given area there was less plant diversity.

但是当季节的变化越来越明显，植物群便逐渐分开，也就是说在一定的区域，植物的种类多样性降低。

9 .And as a result, uh, so the theory goes, the ice-age animals that depended on plant diversity couldn’t survive… and the great beasts were the ones that needed the most diversity in their diet.

按照这种理论，结果那些依赖于植物多样性的动物便无法生存，而那些巨型哺乳动物的饮食是最需要多样性的。

1 .Again, we have what at first seems like a pretty attractive theory…

还是，这个理论开始的时候看起来很有吸引力，

2 .But then, how do you explain the fact that this had happened before— you know, global cooling followed by global warming— and there was no extinction then…

但是接下来，你要如何解释以前也发生过这种情况呢？要知道，全球变冷接着又全球变暖，但是之前却没有发生灭绝。

1 .[Shifting gears] Uh, you know, I recently read an interesting article about an archaeologist who tried to solve this puzzle with the help of his computer.

我最近读了一篇有趣的文章，一位考古学家试图在计算机的帮助下解决这个谜题

2 .What he did was, he wrote a computer program to simulate what would happen to mammoths under certain conditions; um, say, for example, there’s a drought for a couple of decades; or, uh, hunters are killing off 5 percent of the population, and so on…

他写了一个计算机程序模拟在特定情况下猛犸会发生什么，例如，长达几十年的干旱，或者是捕猎者猎杀了百分之五的象群。

3 .One thing he found was that humans didn’t necessarily have to kill these animals in great numbers in order to nudge them toward extinction.

他发现了一点，人们并不需要猎杀大量的这种生物就能将这种生物推向灭绝。

4 .That’s because very large animals have a slow rate of reproduction, so all you have to do is remove a few young females from the herd, and you can—fairly quickly— significantly reduce the population…

因为大型生物的繁殖速度十分缓慢，只要除去象群中的几头年轻的母象，他们的数量就会大幅的下降。

5 .And then he came up with a scenario that combined some hunting by humans with some environmental stress—and bang!

接着他提出了一个假想，人们的猎杀再加上一些环境的压力。

6 .The simulated mammoths were extinct within decades.

这些模拟的猛犸象群在几十年间便灭绝了。

7 .So it seems the mixture of hunting and climate change is a likely scenario…

由此可见，猎杀和气候变化的相互作用可能是猛犸象灭绝的一个假想...

8 .Uh, of course, computer simulations are not a substitute for hard evidence…

当然，电脑模拟并非是一个有力的证据。