听力文摘：高原反应是什么引起的?

Anyone who has vacationed in the higher elevations¹ of Colorado, such as Vail and Estes Park, will tell you altitude sickness can be a real problem.

任何在科罗拉多的高海拔地区如韦尔和洛杉矶国家公园等旅游胜地度过假的人都会告诉你，高原反应真的是要命的问题。

Loss of appetite, nausea², vomiting³, weakness, dizziness, and difficulty sleeping can plague those visiting areas over eight thousand feet.

食欲不振，恶心，呕吐，身体虚弱，头晕，入睡困难等症状可能折磨那些在海拔超过8000英尺区域旅游的人们。

Altitude sickness results from the lack of oxygen at high elevations.

由于海拔较高而缺氧造成高原反应。

At thirteen thousand feet, every lungful of air holds only sixty percent of what it would at sea level.

在13000英尺高的地方，肺仅能容纳海平面高度时60%的空气。

Despite that fact, many indigenous⁴ people live in areas of low oxygen concentration with few adverse⁵ effects.

尽管如此，许多在低氧地区的原居民很少有不良反应。

The big question is, how do they survive?

那么值得我们思考的是，他们是怎样存活的呢？

The body can adapt to low oxygen levels by making more hemoglobin, an oxygen-carrying molecule⁶ in red blood cells.

在氧气稀薄的情况下，身体能够产生一种适应环境的血红蛋白，这种血红蛋白即是红细胞的氧气载体。

But too much hemoglobin over a long period of time can put a person at risk of blood clots⁷, stroke, or chronic⁸ mountain sickness.

但是太多的血红蛋白长时间存在可能导致人体产生血液凝块，患上中风或者患慢性高原病。

Scientists wondered how mountain people can remain healthy living at high altitudes.

科学家想知道在高原生活的人们怎样维持健康。

To see if genes⁹ contribute, scientists analyzed¹⁰ the genomes of three ethnic¹¹ groups living at altitudes over twelve thousand feet, two from Ethiopia, and Tibetans.

科学家们为了证实基因是否有关，他们对3组生活在超过12000 英尺区域种族群体做了染色体分析，其中有两组人来自埃塞俄比亚，另外一组来自西藏。

One Ethiopian group, the Oromo, cope the same way lowlanders do, by making more hemoglobin.

其中一组的埃塞俄比亚奥罗莫人与其他地方人一样，他们的身体产生更多的血红蛋白抵抗低氧环境。

The Amhara and Tibetans, on the other hand, have hemoglobin levels ten percent lower than the Oromo.

阿姆哈拉人和西藏人的血红蛋白含量比奥罗莫人低10%左右。

Does genetic¹² variation account for this?

是基因变异导致这种情况吗？

Scientists found that both the Amhara and Tibetan highlanders possessed¹³ genetic variants¹⁴ associated with low hemoglobin levels.

科学家发现阿姆哈拉人和西藏人都有基因变异以维持低血红蛋白水平。

But they were not the same genes.

但是他们的基因却不同。

It appears that each group took a different evolutionary¹⁵ path to achieve the same outcome of dampening the usual response of increased hemoglobin.

看起来他们走了不同的进化历程，却达到了相同的结果，那就是抑制人体在患高空症时血红蛋白的增长。

How about all those vacationers in Colorado?

在科罗拉多度假的人们怎么办呢？

They will have to make do with their own lowland genes, for now.

目前只能用他们的低地基因来勉强应付了。

1 elevations   

（水平或数量）提高( elevation的名词复数 )； 高地； 海拔； 提升

参考例句：

• Weight of the crust changes as elevations are eroded and materials are deposited elsewhere. 当高地受到侵蚀，物质沉积到别的地方时，地壳的重量就改变。
• All deck elevations are on the top of structural beams. 所有甲板标高线均指结构梁顶线。

2 nausea   

n.作呕，恶心；极端的憎恶(或厌恶)

参考例句：

• Early pregnancy is often accompanied by nausea.怀孕期常有恶心的现象。
• He experienced nausea after eating octopus.吃了章鱼后他感到恶心。

3 vomiting   

吐

参考例句：

• Symptoms include diarrhoea and vomiting. 症状有腹泻和呕吐。
• Especially when I feel seasick, I can't stand watching someone else vomiting." 尤其晕船的时候，看不得人家呕。”

4 indigenous   

adj.土产的，土生土长的，本地的

参考例句：

• Each country has its own indigenous cultural tradition.每个国家都有自己本土的文化传统。
• Indians were the indigenous inhabitants of America.印第安人是美洲的土著居民。

5 adverse   

adj.不利的；有害的；敌对的，不友好的

参考例句：

• He is adverse to going abroad.他反对出国。
• The improper use of medicine could lead to severe adverse reactions.用药不当会产生严重的不良反应。

6 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。

7 clots   

n.凝块( clot的名词复数 )；血块；蠢人；傻瓜v.凝固( clot的第三人称单数 )

参考例句：

• When you cut yourself, blood clots and forms a scab. 你割破了，血会凝固、结痂。 来自《简明英汉词典》
• Milk clots when it turns sour. 奶变酸就凝块。 来自《现代英汉综合大词典》

8 chronic   

adj.(疾病)长期未愈的，慢性的；极坏的

参考例句：

• Famine differs from chronic malnutrition.饥荒不同于慢性营养不良。
• Chronic poisoning may lead to death from inanition.慢性中毒也可能由虚弱导致死亡。

9 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

10 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》

11 ethnic   

adj.人种的，种族的，异教徒的

参考例句：

• This music would sound more ethnic if you played it in steel drums.如果你用钢鼓演奏，这首乐曲将更具民族特色。
• The plan is likely only to aggravate ethnic frictions.这一方案很有可能只会加剧种族冲突。

12 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。

13 possessed   

adj.疯狂的；拥有的，占有的

参考例句：

• He flew out of the room like a man possessed.他像着了魔似地猛然冲出房门。
• He behaved like someone possessed.他行为举止像是魔怔了。

14 variants   

n.变体( variant的名词复数 )；变种；变型；（词等的）变体

参考例句：

• Those variants will be preserved in the'struggle for existence". 这些变异将在“生存竞争”中被保留下来。 来自辞典例句
• Like organisms, viruses have variants, generally called strains. 与其他生物一样，病毒也有变种，一般称之为株系。 来自辞典例句

15 evolutionary   

adj.进化的；演化的，演变的；[生]进化论的

参考例句：

• Life has its own evolutionary process.生命有其自身的进化过程。
• These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。