2006年VOA标准英语-Genealogical Studies Being Aided by DNA Tests

By Greg Flakus
Houston, Texas
24 November 2006
 
watch DNA¹ report

Millions of people around the world can trace their ancestry² back several generations or more through oral history, family documents or government records of such events as marriages and births.  In the United States, genealogy³ has become a popular pursuit especially for descendants of immigrants who are interested in knowing where their forefathers⁵ originated.  These genealogical researchers are being aided these days by DNA tests that can sometimes help them bridge gaps left in the paper trail.  Sometimes these tests can lead to surprises.

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A laboratory technician prepares samples for DNA testing

Roberta Estes has a long list of European family surnames that she has encountered in her search through family records and public documents.

But through DNA testing she found out that she also has genetic⁶ links to sub-Saharan Africa and Native American Indians, bringing her closer to others who descend⁴ from those lines.

One of Roberta's lines has the surname Younger and many people with this name assume that they are related to the infamous⁷ 19th century Missouri outlaw⁸ band led by Cole Younger.  But Roberta says DNA tests have shown not all Youngers are related.

Pointing to her research Roberta says, "There is the Cole Younger and the Younger gang line and then there is another line, even though they both come out of Virginia and Maryland at about the same time, but the DNA has proven that they are two distinct and separate lines."

DNA tests are most useful in determining genetic links between people who may have little documentation or oral history to guide them.  Adrian Williams leads a group of people with the surname Williams, the third most common surname in the United States.  There are many branches of the Williams line that may not be related to one another.  But Adrian says a DNA test has helped him find connections with others who share his surname.

"Although it could not tell us explicitly⁹ that that Reuben was the brother of my George,” says Adrien, “when you take the testing along with all the circumstantial evidence, that makes [bridges] the gap."

"DNA is nothing more than a tool in the toolkit for the genealogist¹⁰ who has run into a paper trail roadblock," says Bennett Greenspan, President and Chief Executive Officer of Family Tree DNA, the Houston-based company that is considered the world leader in genetic testing for genealogical research. "With DNA testing we are able to unravel¹¹ that history book that is contained within the cells of all of us."

The history contained in human genes¹² also links every person on earth to a common genetic origin in Africa.  Natural variations in the genes occurred over time as people migrated out of Africa, according to Adrian Williams.

"As that population started expanding, they started migrating. So you have Africa here and then you get these fingers of migration¹³ out around the world. As that migration is happening, that DNA is also evolving and it is mutating and it is changing."

Family Tree DNA is now working with the National Geographic¹⁴ Society on a large-scale program to trace the migrations¹⁵ of humankind.  One of the experts assisting in this and in the use of DNA for genealogical studies is Professor Michael Hammer, head of the Genomics Analysis and Technology Core at the University of Arizona.

"We do carry mutations that go back a million years in our genome. We also carry mutations that are specific to a particular population,” says Hammer. “Those mutations probably arose in the past few thousand years after that population diverged¹⁶ and separated from their common ancestral population."

Professor Hammer participated in one genealogical study with Jewish people who come from the Cohen line and through oral tradition trace their lineage to the ancient Hebrew priests.  He says the Y chromosome¹⁷ test, which shows genetic links from father to son through many generations, were applied¹⁸ to the research question.

"If two people come from different communities but are both Cohen, would they share a Y chromosome type, more so than you would expect by chance if you sampled two random¹⁹ people from the Jewish population? The answer is yes."

But Professor Hammer says the use of DNA tests also can tell us how all the various genetic lines have crossed and combined over thousands of years.

"Just by the nature of human migration and mixing in the past, we have not remained separated and isolated²⁰ on different continents all these years. We do have a history of migration and our genome will reflect that," said the professor.

Genetic researchers, driven to some extent by demand from people doing genealogical research, keep coming up with new tests and new ways of tracing our genetic connections with one another.

1 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。

2 ancestry   

n.祖先，家世

参考例句：

• Their ancestry settled the land in 1856.他们的祖辈1856年在这块土地上定居下来。
• He is an American of French ancestry.他是法国血统的美国人。

3 genealogy   

n.家系，宗谱

参考例句：

• He had sat and repeated his family's genealogy to her,twenty minutes of nonstop names.他坐下又给她细数了一遍他家族的家谱，20分钟内说出了一连串的名字。
• He was proficient in all questions of genealogy.他非常精通所有家谱的问题。

4 descend   

vt./vi.传下来，下来，下降

参考例句：

• I hope the grace of God would descend on me.我期望上帝的恩惠。
• We're not going to descend to such methods.我们不会沦落到使用这种手段。

5 forefathers   

n.祖先，先人；祖先，祖宗( forefather的名词复数 )；列祖列宗；前人

参考例句：

• They are the most precious cultural legacy our forefathers left. 它们是我们祖先留下来的最宝贵的文化遗产。 来自《简明英汉词典》
• All of us bristled at the lawyer's speech insulting our forefathers. 听到那个律师在讲演中污蔑我们的祖先，大家都气得怒发冲冠。 来自《简明英汉词典》

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 infamous   

adj.声名狼藉的，臭名昭著的，邪恶的

参考例句：

• He was infamous for his anti-feminist attitudes.他因反对女性主义而声名狼藉。
• I was shocked by her infamous behaviour.她的无耻行径令我震惊。

8 outlaw   

n.歹徒，亡命之徒；vt.宣布…为不合法

参考例句：

• The outlaw hid out in the hills for several months.逃犯在山里隐藏了几个月。
• The outlaw has been caught.歹徒已被抓住了。

9 explicitly   

ad.明确地，显然地

参考例句：

• The plan does not explicitly endorse the private ownership of land. 该计划没有明确地支持土地私有制。
• SARA amended section 113 to provide explicitly for a right to contribution. 《最高基金修正与再授权法案》修正了第123条，清楚地规定了分配权。 来自英汉非文学 - 环境法 - 环境法

10 genealogist   

系谱学者

参考例句：

• Misha Defonseca acknowledged her bestselling Holocaust story as a fake after a genealogist outed her. MishaDefonseca在当一位系谱学者揭露她之后承认自己关于二战犹太大屠杀的畅销书是捏造的。

11 unravel   

v.弄清楚（秘密）；拆开，解开，松开

参考例句：

• He was good with his hands and could unravel a knot or untangle yarn that others wouldn't even attempt.他的手很灵巧，其他人甚至都不敢尝试的一些难解的绳结或缠在一起的纱线，他都能解开。
• This is the attitude that led him to unravel a mystery that long puzzled Chinese historians.正是这种态度使他解决了长期以来使中国历史学家们大惑不解的谜。

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 migration   

n.迁移，移居，（鸟类等的）迁徙

参考例句：

• Swallows begin their migration south in autumn.燕子在秋季开始向南方迁移。
• He described the vernal migration of birds in detail.他详细地描述了鸟的春季移居。

14 geographic   

adj.地理学的，地理的

参考例句：

• The city's success owes much to its geographic position. 这座城市的成功很大程度上归功于它的地理位置。 来自《简明英汉词典》
• Environmental problems pay no heed to these geographic lines. 环境问题并不理会这些地理界限。 来自英汉非文学 - 环境法 - 环境法

15 migrations   

n.迁移，移居( migration的名词复数 )

参考例句：

• It foundered during the turmoils accompanying the Great Migrations. 它在随着民族大迁徙而出现的混乱中崩溃。 来自辞典例句
• Birds also have built-in timepieces which send them off on fall and spring migrations. 鸟类也有天生的时间感应器指导它们秋春迁移。 来自互联网

16 diverged   

分开( diverge的过去式和过去分词 )； 偏离； 分歧； 分道扬镳

参考例句：

• Who knows when we'll meet again? 不知几时咱们能再见面！
• At what time do you get up? 你几时起床？

17 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。

18 applied   

adj.应用的；v.应用，适用

参考例句：

• She plans to take a course in applied linguistics.她打算学习应用语言学课程。
• This cream is best applied to the face at night.这种乳霜最好晚上擦脸用。

19 random   

adj.随机的；任意的；n.偶然的(或随便的)行动

参考例句：

• The list is arranged in a random order.名单排列不分先后。
• On random inspection the meat was found to be bad.经抽查，发现肉变质了。

20 isolated   

adj.与世隔绝的

参考例句：

• His bad behaviour was just an isolated incident. 他的不良行为只是个别事件。
• Patients with the disease should be isolated. 这种病的患者应予以隔离。