听力文本

If you look at the limbs what you find is that the joints are all angled
你可以看一下四肢，它们的关节都呈直角
so that the limb would have stretched out just to the sides.
所以四肢伸出来时只能贴住身体两侧
There's just no way that it could have brought its leg underneath to take any weight.
它不可能把腿放到身体下面支撑体重
Similarly with the hind limb, which we found a bit later on, similar kind of arrangement,
我们稍后发现，后肢也是同样的情况，也有类似的结构，
no ankle to speak of, just a paddle like limb.
没有所谓的踝部，长得和桨一样
Acanthostega's legs would have been useless for walking
棘螈的腿根本不适合于行走
and what's more, although it was a fully formed tetrapod it could never have lived out of the water.
另外，尽管它是完全成形的四足动物，它却不能离开水生活
It had gills just like a fish.
它长着和鱼一样的鳃
It meant the evolution of our legs could never have had anything to do with walking on land.
这意味着腿的进化应该和陆上行走毫无关系

Jenny Clack's discovery of the acanthostega had changed everything.
Jenny Clack发现的棘螈改变了一切
The old explanation that we'd evolved our legs after a fish came onto land just could not be true.
原来解释说腿的进化发生在鱼登陆之后，现在看来也并不正确
So the thing that has really changed is that rather than the fish
所以真正的演化过程并不是
going onto the land while it's, it's still got fins we've turned that completely on its head,
鱼带着鳍爬到陆地上，我们已经从根本上推翻了这一观点
so now we've got tetrapods in the water, still in the water, while they've got limbs with digits.
我们现在认为四足动物仍旧在水中，在水里进化出腿和趾。

词汇解析

1.stretch out 伸出；伸直四肢
They stretched out on the grass.
他们伸直四肢平躺在草地上。

2.take weight 支撑体重
If necessary, support your body with a chair to take weight off the knee.
如果必要，可以借助椅子的辅助来减轻膝盖的负重。

3.speak of 所谓的；值得一提
I don't think his handwriting was anything to speak of.
我认为他的书法没什么值得称道的。

4.turn on its head 彻底改变；推翻
Seldom has corporate strategy been turned on its head so quickly.
公司战略从来没有如此快的改变其方向。

视频及简介

19世纪，英国生物学家赫胥黎在研究了尼安德特人的头骨以后，认为是一个具有猿脸的头骨，但决不是人与猿之间的中间缺环。这就告诉我们，人与猿之间的亲缘关系，似乎还应该有一环。1891年发现直立猿人（爪哇猿人）的骨胳，证明这个缺环确实是存在的。可是，日本的人类学家认为爪哇猿人尚不是真正的中间缺环。那么，在猿与人之间到底应该是什么样的一环呢？在埃塞俄比亚发现的早期人科动物化石，很可能是过渡物种。这一发现，弥补了原始人类进化中的一个“缺环”。