VOA标准英语2010-Climate Changes Appear to Coincide with H

U.S. National Research Council calls for more exploration

Rosanne Skirble | Washington, DC 08 April 2010

 
Photo: Smithsonian National Museum of Natural History
Rick Potts has led excavations¹ at early human sites in the East African Rift² Valley, and currently directs a multidisciplinary research team at the famous handaxe site of Olorgesailie, Kenya.

Related Links:

Journal Nature and DNA³ 40,000 year old pinky bone
National Research Council Report
National Museum of Natural History Human Origins Exhibit
Andrew Hill, Yale University

Rick Potts tackles the mysteries of human origins for a living.

For over 25 years, the paleo-anthropologist at the Smithsonian Institution in Washington has led expeditions to East Africa to explore how our early ancestors adapted to changes in landscape and climate.

"You walk up a hillside of this eroded⁴ region of southern Kenya and you see layer after layer that indicates a huge lake was here, but then the lake is gone," says Potts. "Then there's a volcanic⁵ eruption⁶ that covered over all the grass. Animals had to move away. Then there's a river that came through that area. The lake is back and then there's a big drought, on and on, layer after layer — amazing chapters in this story of climate change."

Climate and evolution

Potts says prehistoric⁷ climate changes appear to have coincided with milestones⁸ in human evolution, such as the emergence⁹ of bipedalism — walking on two feet — the development of a larger brain and tool-making skills.  

"What we were able to investigate is how those tool makers¹⁰, using stone hand-axes for hundreds of thousands of years were able to adjust. But then the environmental changes got ramped¹¹ up, and the hand axes disappear, and we see the technologies that are smaller," he says. "We have stone points that were attached to arrows that allowed our direct ancestors, right before the emergence of our own species, to hunt animals and do many more diverse things."

Chip Clark, Smithsonian Institution
Multipurpose tools used to chop wood, butcher animals, and make other tools -- dominated early human technology for more than a million years.

Search for answers

That link between climate and human evolution is the subject of a new National Research Council study. 

Andrew Hill is professor of anthropology¹² at Yale University and part of the team of scientists that contributed to the report. He says efforts to better understand the link between climate and evolution — and to more clearly define those evolutionary¹³ adaptations — are limited by gaps in the fossil record.

"Any time you find something, it's likely that there's some before that you haven't found yet, and so you're not really dating the origin of these things precisely¹⁴," says Hill. "That gets better if you find more stuff. The bigger the size, the more likely you are to have an accurate first-appearance of a new behavior. And that's where we are deficient¹⁵ at the moment and why we need to explore more."

 

Climate and fossil records suggest that some events in human evolution coincided with substantial changes in African and Eurasian climate according to a new report published by the National Research Council.

High-tech¹⁶ exploration

Hill says the research team recommends a major new effort to locate additional sites. And he notes that remote-sensing devices aboard satellites and unmanned aircraft can help to more precisely target where to excavate¹⁷.

"You can actually search for different types of rock because different types of rock give off different types of signal in the non-visible part of the spectrum¹⁸. And so you can look for sedimentary rocks as opposed to volcanic rocks and different kinds of rocks like lake beds where there might be something plausible²⁰."   

Hill says the NRC report also recommends more extensive drilling to extract sediment¹⁹ cores from dry land, lake beds and ocean floors in regions where humans evolved. "In doing that you are also finding more specimens²¹ of other kinds of animals and archeology."

And, Hill adds, computer-generated climate models using data on temperature, precipitation and vegetation near human fossils can be a huge help not only in reconstructing past environments, but in understanding the science of climate change in our own era.  "A very concrete way in which it's useful is that when you are working out models for what will happen in the future, the only way in which you can really test it, is by applying the models to the past where you know what really happened from other signals."

Family tree

Over at the Museum of Natural History in Washington Rick Potts is curator of a new exhibit on human origins.

He is also a contributor to the NRC report, which he says recommends new education programs to build on already-strong public interest in the science of human origins. 

"The idea of being able to trace the emergence of our own species' resilience as the last remaining member of a diverse family tree, and how that evolutionary history interacts with the possibilities of the future, I think are extremely relevant, bringing together these two enormous areas of public curiosity, climate change and human evolution."

Potts says fossil and climate records can bring us a little closer to answering two fundamental questions: What does it mean to be human? And how will our resilient species adapt to a future of changing climate?

 

1 excavations   

n.挖掘( excavation的名词复数 )；开凿；开凿的洞穴（或山路等）；（发掘出来的）古迹

参考例句：

• The excavations are open to the public. 发掘现场对公众开放。
• This year's excavations may reveal ancient artifacts. 今年的挖掘可能会发现史前古器物。 来自辞典例句

2 rift   

n.裂口，隙缝，切口；v.裂开，割开，渗入

参考例句：

• He was anxious to mend the rift between the two men.他急于弥合这两个人之间的裂痕。
• The sun appeared through a rift in the clouds.太阳从云层间隙中冒出来。

3 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。

4 eroded   

adj. 被侵蚀的，有蚀痕的 动词erode的过去式和过去分词形式

参考例句：

• The cliff face has been steadily eroded by the sea. 峭壁表面逐渐被海水侵蚀。
• The stream eroded a channel in the solid rock. 小溪在硬石中侵蚀成一条水道。

5 volcanic   

adj.火山的；象火山的；由火山引起的

参考例句：

• There have been several volcanic eruptions this year.今年火山爆发了好几次。
• Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。

6 eruption   

n.火山爆发；（战争等）爆发；（疾病等）发作

参考例句：

• The temple was destroyed in the violent eruption of 1470 BC.庙宇在公元前1470年猛烈的火山爆发中摧毁了。
• The eruption of a volcano is spontaneous.火山的爆发是自发的。

7 prehistoric   

adj.（有记载的）历史以前的，史前的，古老的

参考例句：

• They have found prehistoric remains.他们发现了史前遗迹。
• It was rather like an exhibition of prehistoric electronic equipment.这儿倒像是在展览古老的电子设备。

8 milestones   

n.重要事件( milestone的名词复数 )；重要阶段；转折点；里程碑

参考例句：

• Several important milestones in foreign policy have been passed by this Congress and they can be chalked up as major accomplishments. 这次代表大会通过了对外政策中几起划时代的事件，并且它们可作为主要成就记录下来。 来自《简明英汉词典》
• Dale: I really envy your milestones over the last few years, Don. 我真的很羡慕你在过去几年中所建立的丰功伟绩。 来自互联网

9 emergence   

n.浮现，显现，出现，（植物）突出体

参考例句：

• The last decade saw the emergence of a dynamic economy.最近10年见证了经济增长的姿态。
• Language emerges and develops with the emergence and development of society.语言是随着社会的产生而产生，随着社会的发展而发展的。

10 makers   

n.制造者，制造商（maker的复数形式）

参考例句：

• The makers of the product assured us that there had been no sacrifice of quality. 这一产品的制造商向我们保证说他们没有牺牲质量。
• The makers are about to launch out a new product. 制造商们马上要生产一种新产品。 来自《简明英汉词典》

11 ramped   

土堤斜坡( ramp的过去式和过去分词 )； 斜道； 斜路； （装车或上下飞机的）活动梯

参考例句：

• With the arrival of George Lucas, the pace has ramped up. 随着乔治·卢卡斯的到来，速度大大加快。
• They also sold corporate bonds as the global financial crisis ramped up. 在全球金融危机加剧之际，他们还抛售了公司债券。

12 anthropology   

n.人类学

参考例句：

• I believe he has started reading up anthropology.我相信他已开始深入研究人类学。
• Social anthropology is centrally concerned with the diversity of culture.社会人类学主要关于文化多样性。

13 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。

14 precisely   

adv.恰好，正好，精确地，细致地

参考例句：

• It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
• The man adjusted very precisely.那个人调得很准。

15 deficient   

adj.不足的，不充份的，有缺陷的

参考例句：

• The crops are suffering from deficient rain.庄稼因雨量不足而遭受损害。
• I always have been deficient in selfconfidence and decision.我向来缺乏自信和果断。

16 high-tech   

adj.高科技的

参考例句：

• The economy is in the upswing which makes high-tech services in more demand too.经济在蓬勃发展，这就使对高科技服务的需求量也在加大。
• The quest of a cure for disease with high-tech has never ceased. 人们希望运用高科技治疗疾病的追求从未停止过。

17 excavate   

vt.挖掘，挖出

参考例句：

• They plan to excavate a large hole.他们计划挖个大洞。
• A new Danish expedition is again excavating the site in annual summer digs.一支新的丹麦探险队又在那个遗址上进行一年一度的夏季挖掘。

18 spectrum   

n.谱，光谱，频谱；范围，幅度，系列

参考例句：

• This is a kind of atomic spectrum.这是一种原子光谱。
• We have known much of the constitution of the solar spectrum.关于太阳光谱的构成，我们已了解不少。

19 sediment   

n.沉淀，沉渣，沉积(物)

参考例句：

• The sediment settled and the water was clear.杂质沉淀后，水变清了。
• Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。

20 plausible   

adj.似真实的，似乎有理的，似乎可信的

参考例句：

• His story sounded plausible.他说的那番话似乎是真实的。
• Her story sounded perfectly plausible.她的说辞听起来言之有理。

21 specimens   

n.样品( specimen的名词复数 )；范例；（化验的）抽样；某种类型的人

参考例句：

• Astronauts have brought back specimens of rock from the moon. 宇航员从月球带回了岩石标本。
• The traveler brought back some specimens of the rocks from the mountains. 那位旅行者从山上带回了一些岩石标本。 来自《简明英汉词典》