Alien Neighbors 寻访外星人 5

Understanding how life got going on our own planet will help us target where we look for it in space, both within the solar system and beyond.

Biophysicist, David Deamer, studies tide pools. A tide pool has the right mix of conditions for the formation of the first simple organisms. "If we think about the kinds of key events that might have been part of the beginning of life, certainly one of them had to be a sufficiently¹ concentrated solution. Life could not have begun in a highly dilute² solution of molecules⁴ because they can't find each other, molecules wander all over the place. The only way they can react is if they bump into one another. So, this means that there must have been a concentrating mechanism⁵. Tide pools are an obvious concentrating mechanism because as a tide pool dries out, everything in it gets more concentrated. "

In his lab, Dr. Deamer wants to see how the first microorganism might have sprung up under similar conditions. "Imagine the tide has gone out, and the pool is drying up, and leaving behind a thin film of organic material. "

Simple organic material likely to have been on earth before life began. "The tide comes back in." The incoming tide churns the matter together. Ultraviolet light, like the sun, adds a heat source. With the agitation⁶ and higher temperatures, something begins to happen. Some of the molecules have formed bubbles and another kind of molecule³ has become trapped inside the bubbles, mimicking⁷ a cell and its nucleus⁸. Although not actually a living thing, this simple structure mimics⁹ a single-celled organism that could have sprung up under similar conditions.

Yellow Stone Park, like a reminder¹⁰ of early earth, it has steaming lakes and hot mud pools that erupt at burning temperatures. A much less forgiving environment than a tide pool, yet here, against all expectations, life has taken hold. Some microorganisms are being fossilized as quickly as they form.

Dr. Jack¹¹ Farmer, one of NASA's exobiologists, if he can understand how simple life forms become fossilized here on earth, space fossils may one day be easier to spot.

"What I'm interested in, in an environment like this, is how organisms are captured during the process of mineralization that occurs and turn into fossils. And, the idea is that the rates at which these minerals are forming is so fast that the organisms don't even have a chance to die before they become entrapped¹² in the minerals. And, that means that you capture a lot of biological information mostly as different types of fabrics¹³ in the rock. So this is a really excellent place to look for microbial fossil information. "

The hot conditions at Yellow Stone are almost like early earth, but not quite. There's too much oxygen.

When life started on this planet, there wasn't any free oxygen in the atmosphere, there was obviously oxygen, in the world, but it was bound oxygen, it wasn't free oxygen. So all the oxygen in the air has come from green plants.



words in this passage:

dilute solution :稀溶液

churn : shake or agitate with violent motion 搅拌

agitation:搅动

mimic: to copy the way in which a particular person usually speaks and moves, usually in order to amuse people:模仿（NOTE：mimicking, mimicked, mimicked）

1 sufficiently   

adv.足够地，充分地

参考例句：

• It turned out he had not insured the house sufficiently.原来他没有给房屋投足保险。
• The new policy was sufficiently elastic to accommodate both views.新政策充分灵活地适用两种观点。

2 dilute   

vt.稀释，冲淡；adj.稀释的，冲淡的

参考例句：

• The water will dilute the wine.水能使酒变淡。
• Zinc displaces the hydrogen of dilute acids.锌置换了稀酸中的氢。

3 molecule   

n.分子，克分子

参考例句：

• A molecule of water is made up of two atoms of hygrogen and one atom of oxygen.一个水分子是由P妈̬f婘̬ 妈̬成的。
• This gives us the structural formula of the molecule.这种方式给出了分子的结构式。

4 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

5 mechanism   

n.机械装置；机构，结构

参考例句：

• The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
• The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。

6 agitation   

n.搅动；搅拌；鼓动，煽动

参考例句：

• Small shopkeepers carried on a long agitation against the big department stores.小店主们长期以来一直在煽动人们反对大型百货商店。
• These materials require constant agitation to keep them in suspension.这些药剂要经常搅动以保持悬浮状态。

7 mimicking   

v.（尤指为了逗乐而）模仿( mimic的现在分词 )；酷似

参考例句：

• She's always mimicking the teachers. 她总喜欢模仿老师的言谈举止。
• The boy made us all laugh by mimicking the teacher's voice. 这男孩模仿老师的声音，逗得我们大家都笑了。 来自辞典例句

8 nucleus   

n.核，核心，原子核

参考例句：

• These young people formed the nucleus of the club.这些年轻人成了俱乐部的核心。
• These councils would form the nucleus of a future regime.这些委员会将成为一个未来政权的核心。

9 mimics   

n.模仿名人言行的娱乐演员，滑稽剧演员( mimic的名词复数 )；善于模仿的人或物v.（尤指为了逗乐而）模仿( mimic的第三人称单数 )；酷似

参考例句：

• Methods:Models were generate by CT scan,Mimics software and Abaqus software. 方法：采用CT扫描，Mimics软件和Abaqus软件的CAD进行三维有限元模型的创建。 来自互联网
• Relaxing the mind and body mimics the effect that some blood-pressure pills would have. 放松身心会产生某些降压药才能产生的效果。 来自辞典例句

10 reminder   

n.提醒物，纪念品；暗示，提示

参考例句：

• I have had another reminder from the library.我又收到图书馆的催还单。
• It always took a final reminder to get her to pay her share of the rent.总是得发给她一份最后催缴通知，她才付应该交的房租。

11 jack   

n.插座，千斤顶，男人；v.抬起，提醒，扛举；n.（Jake）杰克

参考例句：

• I am looking for the headphone jack.我正在找寻头戴式耳机插孔。
• He lifted the car with a jack to change the flat tyre.他用千斤顶把车顶起来换下瘪轮胎。

12 entrapped   

v.使陷入圈套，使入陷阱( entrap的过去式和过去分词 )

参考例句：

• He was entrapped into undertaking the work. 他受骗而担任那工作。 来自《简明英汉词典》
• He felt he had been entrapped into marrying her. 他觉得和她结婚是上了当。 来自辞典例句

13 fabrics   

织物( fabric的名词复数 )； 布； 构造； （建筑物的）结构（如墙、地面、屋顶）：质地

参考例句：

• cotton fabrics and synthetics 棉织物与合成织物
• The fabrics are merchandised through a network of dealers. 通过经销网点销售纺织品。