英语听力—环球英语 789 Our Human Journey

　　Voice 1
Welcome to Spotlight¹. I'm Joshua Leo
Voice 2
And I'm Liz Waid. Spotlight uses a special English method of broadcasting. It is easier for people to understand - no matter where in the world they live.
Voice 1
People. Men and women, old and young. Today, humans cover almost every part of the earth: jungles, forests, cities, and fields. But, how did we get there? Where did we come from? And why do we look so different?
Voice 2
Today's Spotlight is on the Genographic Project. This project is an effort to learn more about human history. Researchers want to understand the human journey, where we came from and how we got to where we live today. The project hopes to map human movement from the beginning of human history until now. To do this, researchers are studying the DNA², or genes³, of many people all over the world.
Voice 1
Have you ever wondered about your family history? Who were your first ancestors? And where did they come from?
Voice 2
Well, facts collected by the Genographic Project seem to point to Africa! Scientists working with the project believe that all people on earth are connected to each other. The Genographic Project states that all of our first ancestors lived in ancient Africa. And from there, people spread all over the earth.
Voice 1
Spencer Wells is a population geneticist. He is also the leader of the Genographic Project. He told reporters,
Voice 3
"The greatest history book ever written is the one hiding in our DNA."
Voice 1
Wells studies the DNA of different people groups all over the world. His research shows that people from all over the world share small parts of their DNA. He thinks that this shared DNA connects people together.
Voice 2
So, how does the Genographic Project work? How does our DNA connect us together?
Voice 1
Well, first it is important to understand how DNA works⁵. DNA is a complex chemical molecule⁶. We all have it in the cells of our body. The structure of your DNA contains a long list of information about you. The molecule controls the way that you look. It controls your eye, hair, and skin colour. It controls how tall you are. Some people even believe that DNA affects your behaviour. And no other person can have the exact same DNA as you.
Voice 2
But, some parts of your DNA will be the same in you and in some other people. Genes are small parts of the DNA molecule. People receive their genes from their parents, half from their mother and half from their father. Parents received their genes from their parents and so on. You share genes with your ancestors who lived many, many years ago.
Voice 1
Scientists like to study the DNA of tribal⁷ native groups best. These people usually mate⁸ within their own ethnic⁹ group. For example, a man from the Suvadi tribe¹⁰ in Nigeria will almost always have children with a woman from the same tribe. New genes from other ethnic groups are not often brought into the tribe. The DNA within the tribe does not experience much change. So it is easy to study the history of tribal DNA.
Voice 2
However, sometimes within a tribal group there will be a mutation¹¹, or small change in the DNA. Many different things in nature can cause a mutation. Sunlight, pollution, and some chemicals are a few things that can cause a mutation. Mutations happen naturally. People cannot stop mutations.
Voice 1
Mutations show as a change in the DNA. The change will be visible¹² in the DNA of the person and his children, his children's children, and so on. Scientists choose some of the mutations for careful study. Scientists call these mutations, "markers." A person today could have many "markers" in his DNA. These markers represent his ancestors from the past. Different populations carry their own special markers in their DNA. Scientists can learn a person's genetic⁴ history by studying "markers."
Voice 2
For example, consider what happens if a man leaves his tribe. What happens if he mates¹³ with someone outside of the tribe? Their DNA will mix. Their baby will share the parents' DNA. That means the baby will also receive his parents' DNA "markers."
Voice 1
Now imagine if that child moved to another country to attend university. At university he meets a young woman. She belongs to a different ethnic group. She even has a different skin colour. The two fall in love, get married, and have a baby of their own. The baby's DNA now has "markers" from his mother and his father. His DNA has markers from three different ethnic groups. Scientists could study this child's DNA. They could discover where his parents came from. They could follow the "markers" to learn about the child's ancestors.
Voice 2
The Genographic Project is interested in "markers" for two reasons. First, "markers" help scientists follow the human path. Imagine a person living in Ecuador. Imagine that his DNA has three particular genetic markers. One of these markers is the same as Native Americans living in the United States. The other marker is the same as people living in Northern Russia. And the last marker is the same as a tribe in Africa. Scientists try to figure out what this means.
Voice 1
The Genographic Project says that the meaning is very important. First, people with the project believe that studying markers shows us the movement of humans. Our example person lived in Ecuador. He had markers from North America, Central Asia, and Africa. His ancestors may have started in Africa, then travelled through Asia, North America, and into South America, ending in Ecuador. This movement may have taken thousands of years.
Voice 2
Second, genetic "markers" show connections between people. Facts collected by the Genographic Project show these connections. All the DNA that the Project has tested shares "markers" with Africans - modern day Africans and the remains¹⁴ of ancient African people. That leads researchers to believe that all people groups started in ancient Africa.
Voice 1
The sharing of genetic "markers" is an important discovery. However, there are some concerns about the project. Native people in some countries do not want to join. They do not trust the researchers. In the past, scientists studied native groups without consent¹⁵ - the native groups did not agree to the studies. These past scientific studies did not bring anything good to the native people. In the United States, and some other places, native groups have argued against taking part in the Genographic Project. They believe that the information could weaken¹⁶ their claims to their land.
However, the Genographic Project has worked carefully with native groups. If a group does not want to give genetic material, researchers go to other groups. They work with communities to share information, so that everyone can learn about their genetic history. Because of this, many native groups HAVE agreed to take part.
 

1 spotlight   

n.公众注意的中心，聚光灯，探照灯，视听，注意，醒目

参考例句：

• This week the spotlight is on the world of fashion.本周引人瞩目的是时装界。
• The spotlight followed her round the stage.聚光灯的光圈随着她在舞台上转。

2 DNA   

(缩)deoxyribonucleic acid 脱氧核糖核酸

参考例句：

• DNA is stored in the nucleus of a cell.脱氧核糖核酸储存于细胞的细胞核里。
• Gene mutations are alterations in the DNA code.基因突变是指DNA密码的改变。

3 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

4 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。

5 works   

n.作品，著作；工厂，活动部件，机件

参考例句：

• We expect writers to produce more and better works.我们期望作家们写出更多更好的作品。
• The novel is regarded as one of the classic works.这篇小说被公认为是最优秀的作品之一。

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 tribal   

adj.部族的，种族的

参考例句：

• He became skilled in several tribal lingoes.他精通几种部族的语言。
• The country was torn apart by fierce tribal hostilities.那个国家被部落间的激烈冲突弄得四分五裂。

8 mate   

n.伙伴，同事；配偶；大副；v.(使)交配

参考例句：

• Where is the mate to this glove?这副手套的另一只在哪儿？
• She has been a faithful mate to him.她一直是他忠实的配偶。

9 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。

10 tribe   

n.部落，种族，一伙人

参考例句：

• This is a subject tribe.这是个受他人统治的部落。
• Many of the tribe's customs and rituals are as old as the hills.这部落的许多风俗、仪式都极其古老。

11 mutation   

n.变化，变异，转变

参考例句：

• People who have this mutation need less sleep than others.有这种突变的人需要的睡眠比其他人少。
• So far the discussion has centered entirely around mutation in the strict sense.到目前为止，严格来讲，讨论完全集中于围绕突变问题上。

12 visible   

adj.看得见的，明显的，显然的；n.可见物

参考例句：

• It is a visible star in the sky.这是一颗在天空中可见的星星。
• The warning lights were clearly visible.警示信号灯清晰可见。

13 mates   

[英]伙伴( mate的名词复数 )； 同伴； （非正式）配偶； （熟练工人的）助手

参考例句：

• He's out boozing with his mates. 他和他的朋友们喝酒去了。
• They've been best mates since school. 他们从上学时期以来就是最要好的朋友。

14 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

15 consent   

n.同意，准许；vi.同意，准许

参考例句：

• I agree with you, but yet I can't consent.我同意你的意见，但是我不能答应。
• My father would not consent to my leaving school.父亲不会答应我辍学。

16 weaken   

v.(使)变弱，(使)虚弱

参考例句：

• You can weaken the tea by adding water.你可以加水把茶弄得淡一些。
• We never weaken our efforts in face of difficulties.我们在困难面前从不软化我们的努力。