时差N小时 蛇的祖先

Scientists have been debating this question for a long time.

科学家们围绕这个问题已经争论了很长的时间。

Some believed that snakes evolved on land,and that their ancestors were small,burrowing¹ lizards³.

一些科学家认为蛇从陆地上进化而来，它们的祖先是小的，穴居的蜥蜴。

And others believed that snakes evolved fromthe mosasaurs, giant swimming lizards that lived 144 to 65 million years ago.

另一些科学家认为蛇由沧龙进化而来，沧龙是生活在一亿四千四百万年前至六千五百万年前的一种巨型水生蜥蜴。

Except it's difficult to analyze⁴ the genes⁵ of the extinct mosasaurs.

分析已经灭绝的沧龙的基因是非常困难的。

So instead, scientists at Penn Stateanalyzed the genes of their closest living relatives, the monitor lizards.

所以宾夕法尼亚州立大学的科学家们分析了它们现存的最近亲属巨蜥的基因。

In fact, these scientists examinedgenetic material representing all nineteen living lizard² families, and seventeen of the twenty-five familiesof living snakes.

实际上，这些科学家们检查了代表所有19种现存蜥蜴家族以及蛇的25种现存家族中的17种基因材料。

They analyzed⁶ the differences in genetic⁷ structure that inevitably⁸ result from the slight mutations that develop over time.

他们分析了随着时间的推移，遗传结构中不可避免的微小变化所带来的差异。

This enabled them to map a genetic family tree.

这让他们能够绘画出一个基因家谱图。

They discovered that snakes aren'tclosely related to monitor lizards.

他们发现了什么呢？他们发现了蛇与巨蜥并没有密切的关系。

Now, because the mosasaurs– the monitor lizards' ancestors–werethe only marine⁹ lizards around when snakes evolved, snakes must have evolved from lizards living onland.

现在，因为沧龙-巨蜥的祖先-是蛇进化时周围唯一的海洋蜥蜴，所以蛇应该是从在陆地上生活的蜥蜴进化而来。

There's a strong correlation¹⁰ between the burrowing lifestyle and very small limbs or the complete lossof limbs.

从穴居生活到非常小的四肢，再到完全丧失四肢，这之间的关联非常强。

Some burrowing lizards have reduced limbs and some have lost one or both pairs.

一些穴居蜥蜴的四肢减少，一些已经失去了一个或者所有的四肢。

After all,you could fit into much smaller openings if you didn't need a pelvis or shoulders to support your limbs.

毕竟,你需要适应更小的通道，如果你不需要骨盆或肩膀来支撑你的肢体。

1 burrowing   

v.挖掘（洞穴），挖洞( burrow的现在分词 )；翻寻

参考例句：

• What are you burrowing around in my drawer for? 你在我抽屉里乱翻什么？ 来自《简明英汉词典》
• The forepaws are also used for burrowing and for dragging heavier logs. 它们的前爪还可以用来打洞和拖拽较重的树干。 来自辞典例句

2 lizard   

n.蜥蜴，壁虎

参考例句：

• A chameleon is a kind of lizard.变色龙是一种蜥蜴。
• The lizard darted out its tongue at the insect.蜥蜴伸出舌头去吃小昆虫。

3 lizards   

n.蜥蜴( lizard的名词复数 )

参考例句：

• Nothing lives in Pompeii except crickets and beetles and lizards. 在庞培城里除了蟋蟀、甲壳虫和蜥蜴外，没有别的生物。 来自辞典例句
• Can lizards reproduce their tails? 蜥蜴的尾巴断了以后能再生吗？ 来自辞典例句

4 analyze   

vt.分析，解析 (=analyse)

参考例句：

• We should analyze the cause and effect of this event.我们应该分析这场事变的因果。
• The teacher tried to analyze the cause of our failure.老师设法分析我们失败的原因。

5 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

6 analyzed   

v.分析( analyze的过去式和过去分词 )；分解；解释；对…进行心理分析

参考例句：

• The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
• The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程，因为对他来说，爱是个不可分析的迷。 来自《简明英汉词典》

7 genetic   

adj.遗传的，遗传学的

参考例句：

• It's very difficult to treat genetic diseases.遗传性疾病治疗起来很困难。
• Each daughter cell can receive a full complement of the genetic information.每个子细胞可以收到遗传信息的一个完全补偿物。

8 inevitably   

adv.不可避免地；必然发生地

参考例句：

• In the way you go on,you are inevitably coming apart.照你们这样下去，毫无疑问是会散伙的。
• Technological changes will inevitably lead to unemployment.技术变革必然会导致失业。

9 marine   

adj.海的；海生的；航海的；海事的；n.水兵

参考例句：

• Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
• When the war broke out,he volunteered for the Marine Corps.战争爆发时，他自愿参加了海军陆战队。

10 correlation   

n.相互关系，相关，关连

参考例句：

• The second group of measurements had a high correlation with the first.第二组测量数据与第一组高度相关。
• A high correlation exists in America between education and economic position.教育和经济地位在美国有极密切的关系。