2007年VOA标准英语-Latest Research Says Modern Man Comes from Afri

By Jessica Berman
Washington
19 July 2007

The origin of modern humans has been a heated topic among anthropologists, who have debated whether modern man came from Africa or somewhere else.   Now, researchers say they have they have proof beyond dispute of the so-called "out of Africa" theory.   VOA's Jessica Berman reports.

The "out of Africa" theory holds that modern humans emerged from the continent some 50,000 years ago, replacing more primitive¹ species including Neanderthals that existed on different continents.

The alternative theory, called the multiregional hypothesis, is that modern humans evolved from primitive species in many places around the world.

But in the 1990s, the multiregional hypothesis was largely discredited² by the advent³ of genetic⁴ testing.

Still, biologist Andrea Manica of Cambridge University in England says there are anthropologists who believe in the multiregional theory. 

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She says that is because of differences in the appearance, or morphology, of primitive human skulls⁶ that have been uncovered on different continents.

"What we did, which I think really in a way brings the whole discussion slightly to a close, is actually to look at genetics and skull morphometrics at the same time with a single sort of framework," she explained.  "And actually show that if you ask the question explicitly⁷, 'Do we come from Africa?'  Then the answer is yes no matter whether you look at genetics or whether you look at morphometrics."

Manica and colleagues measured 4,500 ancient human skulls from more than 100 populations around the world.  She says the size and shape of the skulls were compared to those unearthed⁸ in Africa, which she says has a very diverse population.

"You find for example in terms of skulls, quite of a lot of variability on the traits," she added.  "You know, how broad faces are and how narrow and deep, and so on."

The investigators⁹ discovered that the greater the distance from Africa, the less variability there was among the skulls.

"So, if you take skulls from a population in Africa, there is lots of variability," she noted¹⁰.  "If you go to Europe, there's a little bit less.  If you go to Asia, it's going further down.  If you go then to North America, it goes further down.  And South America is really the most homogeneous in a way of [set] populations."

Manica says that the modern humans who left Africa were far less diverse than the human ancestors who remained behind.  And those that traveled further afield were physically¹¹ even less diverse, contributing to more physical uniformity on the continents where they settled. 

The study of the origins of modern humans appears in the current issue of the journal Nature.

1 primitive   

adj.原始的；简单的；n.原(始)人，原始事物

参考例句：

• It is a primitive instinct to flee a place of danger.逃离危险的地方是一种原始本能。
• His book describes the march of the civilization of a primitive society.他的著作描述了一个原始社会的开化过程。

2 discredited   

不足信的，不名誉的

参考例句：

• The reactionary authorities are between two fires and have been discredited. 反动当局弄得进退维谷，不得人心。
• Her honour was discredited in the newspapers. 她的名声被报纸败坏了。

3 advent   

n.(重要事件等的)到来，来临

参考例句：

• Swallows come by groups at the advent of spring. 春天来临时燕子成群飞来。
• The advent of the Euro will redefine Europe.欧元的出现将重新定义欧洲。

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 skull   

n.头骨；颅骨

参考例句：

• The skull bones fuse between the ages of fifteen and twenty-five.头骨在15至25岁之间长合。
• He fell out of the window and cracked his skull.他从窗子摔了出去，跌裂了颅骨。

6 skulls   

颅骨( skull的名词复数 )； 脑袋； 脑子； 脑瓜

参考例句：

• One of the women's skulls found exceeds in capacity that of the average man of today. 现已发现的女性颅骨中，其中有一个的脑容量超过了今天的普通男子。
• We could make a whole plain white with skulls in the moonlight! 我们便能令月光下的平原变白，遍布白色的骷髅！

7 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

8 unearthed   

出土的（考古）

参考例句：

• Many unearthed cultural relics are set forth in the exhibition hall. 展览馆里陈列着许多出土文物。
• Some utensils were in a state of decay when they were unearthed. 有些器皿在出土时已经残破。

9 investigators   

n.调查者，审查者( investigator的名词复数 )

参考例句：

• This memo could be the smoking gun that investigators have been looking for. 这份备忘录可能是调查人员一直在寻找的证据。
• The team consisted of six investigators and two secretaries. 这个团队由六个调查人员和两个秘书组成。 来自《简明英汉词典》

10 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

11 physically   

adj.物质上，体格上，身体上，按自然规律

参考例句：

• He was out of sorts physically,as well as disordered mentally.他浑身不舒服，心绪也很乱。
• Every time I think about it I feel physically sick.一想起那件事我就感到极恶心。