VOA标准英语2009年-Study Provides New Evidence for Geneti

Véronique LaCapra | Washington 02 December 2009

 
A very small genetic² difference between humans and chimpanzees may help explain why chimpanzees can't speak, but humans can

The ability to communicate using complex spoken language is a uniquely human characteristic, but surprisingly little is known about how we developed language when our close primate³ relatives, like chimpanzees, did not. A single gene¹ may hold much of the answer.

Researchers investigate the genetic basis of language

Dan Geschwind is a professor of neurology, psychiatry⁴ and human genetics at the University of California in Los Angeles. He says we still do not know much about how language evolved in humans. "But it clearly is going to reside in changes in genes⁵: either new genes, or changes in old genes that gives them new functions."

Genes carry hereditary⁶ biological information that determines much about who we are, from our height to our hair color to which hand we use to write with. Geschwind has been studying the function of one particular gene, called FOXP2. "It's one of the few genes that's been very clearly tied to the capacity for human speech and language."

FOXP2 works in an interesting way, Geschwind says. "It turns other things on and off."  Specifically, it regulates other genes. In a cell, FOXP2 acts like a master switch, producing a protein that binds⁷ to other genes and increases or decreases their activity.

FOXP2 protein almost identical in humans and chimps⁸

In spite of FOXP2's apparent role in human speech, it turns out that our FOXP2 protein is almost identical to the version found in our closest primate relative, the chimpanzee. "A protein like FOXP2 is made up of hundreds of amino acids," says Geschwind. "And just two of them are different between human and chimpanzee."

Previous work by other researchers had suggested that the amino acid composition of the human FOXP2 protein may have changed at about the same time in evolutionary⁹ history that humans started to speak. Could a difference in just two amino acids trigger enough changes in downstream gene function to create the capacity for language?

In humans and chimps, FOXP2 behaves differently

Genevieve Konopka, a postdoctoral fellow in the Geschwind lab, led a study to look into this question. She says the purpose of the study was to determine whether the difference between the human version of FOXP2 and the chimpanzee version of FOXP2 would have any functional¹⁰ consequence in neurons.

Brain cells expressing human FOXP2. Cells that are orange/red have high FOXP2 expression

Konopka looked at the effects of FOXP2 on human neurons, or brain cells, in cell cultures in the lab. She manipulated the cells to express - or produce - either the human version of the FOXP2 protein, or the chimpanzee version. "And then we used something called a microarray, which allows you to examine the expression of every gene in the genome."

Konopka found that the human and chimpanzee versions of FOXP2 did function differently in human brain cells, targeting different genes and triggering different levels of gene activity.

Dan Geschwind says similar differences in gene expression were observed in brain tissue samples taken from humans and chimps that died of natural causes. The samples were frozen soon after death to retain the characteristics of living tissue.

The researchers saw a very big overlap¹¹ in what the genes were doing in the cell culture, and in the brains. "And this gave us a lot of confidence that what we were actually seeing was relevant to brain function."

Genes regulated by FOXP2 likely to play role in language and speech

Geschwind says that many of the genes and proteins affected¹² by FOXP2 are known to have functions in the brain, but that others may be involved in the development of the physical apparatus¹³ of speech, like the larynx and vocal¹⁴ chords.

Because to have spoken language, two things had to happen, says Geschwind. The first was a change in vocal anatomy¹⁵. "Our vocal chords, tongue, and all of that changed to allow us to speak. But of course the major thing that happened was the changes in the brain that gave us the capacity for language."

Geschwind emphasizes that speech and language are very connected, and that at least one connection may be via FOXP2.

Geschwind and Konopka say the next step in their research will be to look more closely at the genes FOXP2 regulates, and to investigate their possible role in disorders¹⁶ affecting speech and language. Their current study is published in the journal Nature.
 

1 gene   

n.遗传因子，基因

参考例句：

• A single gene may have many effects.单一基因可能具有很多种效应。
• The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。

2 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。

3 primate   

n.灵长类（目）动物，首席主教；adj.首要的

参考例句：

• 14 percent of primate species are highly endangered.14%的灵长类物种处于高度濒危状态。
• The woolly spider monkey is the largest primate in the Americas.绒毛蛛猴是美洲最大的灵长类动物。

4 psychiatry   

n.精神病学，精神病疗法

参考例句：

• The study appeared in the Amercian science Journal of Psychiatry.这个研究发表在美国精神病学的杂志上。
• A physician is someone who specializes in psychiatry.精神病专家是专门从事精神病治疗的人。

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 hereditary   

adj.遗传的，遗传性的，可继承的，世袭的

参考例句：

• The Queen of England is a hereditary ruler.英国女王是世袭的统治者。
• In men,hair loss is hereditary.男性脱发属于遗传。

7 binds   

v.约束( bind的第三人称单数 )；装订；捆绑；（用长布条）缠绕

参考例句：

• Frost binds the soil. 霜使土壤凝结。 来自《简明英汉词典》
• Stones and cement binds strongly. 石头和水泥凝固得很牢。 来自《简明英汉词典》

8 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

9 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。

10 functional   

adj.为实用而设计的，具备功能的，起作用的

参考例句：

• The telephone was out of order,but is functional now.电话刚才坏了，但现在可以用了。
• The furniture is not fancy,just functional.这些家具不是摆着好看的，只是为了实用。

11 overlap   

v.重叠，与…交叠；n.重叠

参考例句：

• The overlap between the jacket and the trousers is not good.夹克和裤子重叠的部分不好看。
• Tiles overlap each other.屋瓦相互叠盖。

12 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

13 apparatus   

n.装置，器械；器具，设备

参考例句：

• The school's audio apparatus includes films and records.学校的视听设备包括放映机和录音机。
• They had a very refined apparatus.他们有一套非常精良的设备。

14 vocal   

adj.直言不讳的；嗓音的；n.[pl.]声乐节目

参考例句：

• The tongue is a vocal organ.舌头是一个发音器官。
• Public opinion at last became vocal.终于舆论哗然。

15 anatomy   

n.解剖学，解剖；功能，结构，组织

参考例句：

• He found out a great deal about the anatomy of animals.在动物解剖学方面，他有过许多发现。
• The hurricane's anatomy was powerful and complex.对飓风的剖析是一项庞大而复杂的工作。

16 disorders   

n.混乱( disorder的名词复数 )；凌乱；骚乱；（身心、机能）失调

参考例句：

• Reports of anorexia and other eating disorders are on the increase. 据报告，厌食症和其他饮食方面的功能紊乱发生率正在不断增长。 来自《简明英汉词典》
• The announcement led to violent civil disorders. 这项宣布引起剧烈的骚乱。 来自《简明英汉词典》