2005年NPR美国国家公共电台九月-Scientists: Male Chromosome Won't Lead to

Scientists at the Whitehead Institute in Cambridge, Massachusetts say it's fortunate for humans that the Y chromosome¹ is not on the verge² of extinction³. That's because the Y is the chromosome that makes males males. The outlook is less favorable for the chimpanzee Y chromosome. NPR's Jay Palca has our report.

The Y chromosome holds a special fascination⁵ for David Page. Page is a geneticist and now the director of the Whitehead institute. The Y is unique among human chromosomes⁷. All the others come in pairs but there is not counterpart to Y. Two years ago Page and his colleagues produced a detailed⁸ picture of the genetic⁶ makeup⁹ of the human Y chromosome. Since then, he has been working on a similar picture of the chimpanzee Y. Page wanted to learn if anything had changed in the 6 million years since human separated from chimps¹⁰ on the evolutionary¹¹ tree. The results appear in today's issue of the journal Nature.

What we found, much to our surprise, was that it looked as though almost nothing had changed on the human Y chromosome during the past 6 million years. Page says the reason that it's a surprise is that some have suggested the genes¹² on the Y are disappearing. After all, when the Y first emerged as the genetic entity¹³ 3 hundred million years ago, Page says, the Y chromosome had on the order of a thousand genes. Today it has on the order of 80. At that rate, the Y could be gone in ten million years or so.

If the Y is in the process of running into the ground within the next ten million years, then surely there should be evidence if that process had been playing out during the last six million years, and in fact, we find quite the opposite.

On the other hand, Page says some of the genes in the chimpanzee do seem to be accumulating errors and could risk rotting away in time. Page isn't sure why this is happening, but he has a theory.

Chimps are much more promiscuous¹⁴ resulting in what can be called sperm¹⁵ competition. Multiple males mate with a female chimp⁴ in a short period of time.

To be successful in this sperm competition, you want Y chromosomes with good sperm producing genes. Page says the other genes on Y may suffer as a result. In the chimpanzee lineage several of these genes may have been civilian¹⁶ casualties of the sperm war that's really focused on the Y chromosome sperm production genes.

Now these casualties probably don't spell big problems for male chimpanzees. Brian Charleswoods is a geneticist at the University of Edinburgh. These are probably minor¹⁷ effects on the fitness, not probably even easy to measure, you know, unless you count thousands and thousands of individuals. Charleswoods says many of the Y genes have counterparts on the X chromosome, and since males have both an X and a Y, the X genes can step up if the Y genes are damaged, so Charleswoods says a decaying Y probably does not mean/ the chimpanzee species is in trouble. Not because of its Y chromosome, its probably severely¹⁸ danger of departing the world because of human activities leading to their extinction. That's another issue.
And not one you can blame on the Y chromosome.

Joe Palca, NPR news, Washington.

1 chromosome   

n.染色体

参考例句：

• Chromosome material with exhibits of such behaviour is called heterochromatin.表现这种现象的染色体物质叫做异染色质。
• A segment of the chromosome may become lost,resulting in a deletion.染色体的一个片段可能会丢失，结果产生染色体的缺失。

2 verge   

n.边，边缘；v.接近，濒临

参考例句：

• The country's economy is on the verge of collapse.国家的经济已到了崩溃的边缘。
• She was on the verge of bursting into tears.她快要哭出来了。

3 extinction   

n.熄灭，消亡，消灭，灭绝，绝种

参考例句：

• The plant is now in danger of extinction.这种植物现在有绝种的危险。
• The island's way of life is doomed to extinction.这个岛上的生活方式注定要消失。

4 chimp   

n.黑猩猩

参考例句：

• In fact,the color of gorilla and chimp are light-color.其实大猩猩和黑猩猩的肤色是较为浅的。
• The chimp is the champ.猩猩是冠军。

5 fascination   

n.令人着迷的事物，魅力，迷恋

参考例句：

• He had a deep fascination with all forms of transport.他对所有的运输工具都很着迷。
• His letters have been a source of fascination to a wide audience.广大观众一直迷恋于他的来信。

6 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。

7 chromosomes   

n.染色体( chromosome的名词复数 )

参考例句：

• Chromosomes also determine the sex of animals. 染色体也决定动物的性别。 来自《简明英汉词典》
• Each of four chromosomes divide longitudinally. 四种染色体的每一种都沿着纵向分裂。 来自《现代汉英综合大词典》

8 detailed   

adj.详细的，详尽的，极注意细节的，完全的

参考例句：

• He had made a detailed study of the terrain.他对地形作了缜密的研究。
• A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。

9 makeup   

n.组织；性格；化装品

参考例句：

• Those who failed the exam take a makeup exam.这次考试不及格的人必须参加补考。
• Do you think her beauty could makeup for her stupidity?你认为她的美丽能弥补她的愚蠢吗？

10 chimps   

（非洲）黑猩猩( chimp的名词复数 )

参考例句：

• Chimps are too scarce, and too nearly human, to be routinely slaughtered for spare parts. 黑猩猩又太少，也太接近于人类，不可以作为人器官备用件说杀就杀。 来自英汉非文学 - 生命科学 - 医学的第四次革命
• And as nonprimates, they provoke fewer ethical and safety-related concerns than chimps or baboons. 而且作为非灵长类，就不会产生像用黑猩猩或狒狒那样的伦理和安全方面的顾虑。 来自英汉非文学 - 生命科学 - 医学的第四次革命

11 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。

12 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

13 entity   

n.实体，独立存在体，实际存在物

参考例句：

• The country is no longer one political entity.这个国家不再是一个统一的政治实体了。
• As a separate legal entity,the corporation must pay taxes.作为一个独立的法律实体，公司必须纳税。

14 promiscuous   

adj.杂乱的，随便的

参考例句：

• They were taking a promiscuous stroll when it began to rain.他们正在那漫无目的地散步，突然下起雨来。
• Alec know that she was promiscuous and superficial.亚历克知道她是乱七八糟和浅薄的。

15 sperm   

n.精子，精液

参考例句：

• Only one sperm fertilises an egg.只有一个精子使卵子受精。
• In human reproduction,one female egg is usually fertilized by one sperm.在人体生殖过程中，一个精子使一个卵子受精。

16 civilian   

adj.平民的，民用的，民众的

参考例句：

• There is no reliable information about civilian casualties.关于平民的伤亡还没有确凿的信息。
• He resigned his commission to take up a civilian job.他辞去军职而从事平民工作。

17 minor   

adj.较小(少)的，较次要的；n.辅修学科；vi.辅修

参考例句：

• The young actor was given a minor part in the new play.年轻的男演员在这出新戏里被分派担任一个小角色。
• I gave him a minor share of my wealth.我把小部分财产给了他。

18 severely   

adv.严格地；严厉地；非常恶劣地

参考例句：

• He was severely criticized and removed from his post.他受到了严厉的批评并且被撤了职。
• He is severely put down for his careless work.他因工作上的粗心大意而受到了严厉的批评。