VOA标准英语2014--Ancient Tooth Plaque Reveals Diet

 

Ancient Tooth Plaque¹ Reveals Diet

Long before the development of agriculture, our prehistoric² ancestors had a good knowledge of plants – not just for food, but for medicine. Researchers found evidence of this by studying some ancient teeth found in Central Sudan.

Dental hygiene³ has become an important part of modern-day health care. And many millions of dollars are spent every year to get or keep teeth and gums healthy. One of the things dentists warn their patients about is dental calculus⁴ or tarter⁵ – a very hard form of plaque that forms around teeth. It may take a lot of scraping or the use of ultrasonic⁶ tools to remove it.

That type of plaque has given researchers an insight into people who lived thousands of years ago along the White Nile at Al Khiday. It’s about 25 kilometers south of Omdurman.

Karen Hardy⁷ is the lead author of a study published in PLOS ONE. She and her colleagues went to the site to analyze⁸ the compounds clinging to the ancient teeth.

“We were approached by the excavators of the Sudanese site. We were very interested in working at this site because it has a long sequence and it’s also in a relatively⁹ hot area. And we wanted to whether the chemical compounds survived right through the sequence. And, in fact, in this hot place, we discovered that they survived very well, indeed.”

Hardy is a research professor at the Catalan Institution for Research and Advanced Studies at the Autonomous¹⁰ University of Barcelona.

She said, “It’s a little bit like when you go out into an archeological site. Until you start looking you don’t really know what you’re going to find. We were hoping for evidence of ancient diet, particularly evidence of the use of plants in ancient diets before agriculture developed. That’s something that is very difficult to get hold of. It’s very difficult to find.”

But they did find it and the tartar told a tale. The people of Al Khiday were well aware of the use of plants thousands of years before agriculture arrived on the scene in 4500 BC and long after.

“We found evidence of plants. We could see the physical evidence in the form of the microfossils on microscope slides. And we also got chemical compounds that pointed¹¹ in this case specifically to this plant purple nut sedge right through the sequence. In ancient Egypt, it was used as a component¹² of perfume. It was used in water purification. And it also has a lot of medicinal uses that have been recorded by the ancient Greeks and the ancient Egyptians,” said Hardy.

It’s believed purple nut sedge may have the ability to inhibit¹³ the growth of Streptococcus mutans. It’s bacteria that help cause tooth decay. And its effectiveness appears to be borne out in many ancient teeth which showed few cavities.

However, purple nut sedge is not so popular today. In fact, Hardy said it’s now considered a “scourge” in tropical and sub-tropical regions. It’s been called the “world’s most expensive weed” because it’s so invasive and costs so much to eradicate¹⁴ once it invades agricultural fields.

Nevertheless, Hardy said the discovery of its widespread use in ancient Central Sudan tells a lot about the population.

“It’s very clear that they were very well integrated into their environment -- that they understood their environments very well -- that they knew how to exploit the things that were available in their environment. I think that we probably grossly underestimated their abilities actually.”

The findings also shed light on their pre-historic diet and dispel¹⁵ some misconceptions.

Hardy said, “Up to the present, the evidence has not been there for plants. There has been a strong focus on the use of meat, meat products, simply because that is what is found. It’s found in evidence for animal bones spread across sites -- strong evidence of protein. And there simply has not been the evidence there for the plants. Now hopefully with this kind of study that we’re doing we’re going to be able to start getting closer to identifying some of the plant based things that people ate. Because, of course, they really had to eat plants. You can’t survive on protein alone.”

Professor Hardy and her colleagues are now working on many different archeological sites with varying time periods. She said that they may discover the use of other plants by ancient people long since forgotten.

1 plaque   

n.饰板，匾，(医)血小板

参考例句：

• There is a commemorative plaque to the artist in the village hall.村公所里有一块纪念该艺术家的牌匾。
• Some Latin words were engraved on the plaque. 牌匾上刻着些拉丁文。

2 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。

3 hygiene   

n.健康法，卫生学 （a.hygienic）

参考例句：

• Their course of study includes elementary hygiene and medical theory.他们的课程包括基础卫生学和医疗知识。
• He's going to give us a lecture on public hygiene.他要给我们作关于公共卫生方面的报告。

4 calculus   

n.微积分；结石

参考例句：

• This is a problem where calculus won't help at all.对于这一题，微积分一点也用不上。
• After studying differential calculus you will be able to solve these mathematical problems.学了微积分之后，你们就能够解这些数学题了。

5 tarter   

tart（酸的，辛辣的）的比较级形式

参考例句：

• Bruce Tarter, who has directed Lawrence Livermore National Laboratory for the past eight years. 1975年，塔特拿到博士学位，其间除了念书，她还得忙著抚养第一次婚姻生下的女儿。 来自互联网

6 ultrasonic   

adj.超声的；n.超声波

参考例句：

• It was very necessary for people to take type-B ultrasonic inspection regularly.定期进行B超检查是十分必要的。
• Sounds are classified into two kinds: sonic and ultrasonic.声波分为两类，即普通声波与超声波。

7 hardy   

adj.勇敢的，果断的，吃苦的；耐寒的

参考例句：

• The kind of plant is a hardy annual.这种植物是耐寒的一年生植物。
• He is a hardy person.他是一个能吃苦耐劳的人。

8 analyze   

vt.分析，解析 (=analyse)

参考例句：

• We should analyze the cause and effect of this event.我们应该分析这场事变的因果。
• The teacher tried to analyze the cause of our failure.老师设法分析我们失败的原因。

9 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

10 autonomous   

adj.自治的；独立的

参考例句：

• They proudly declared themselves part of a new autonomous province.他们自豪地宣布成为新自治省的一部分。
• This is a matter that comes within the jurisdiction of the autonomous region.这件事是属于自治区权限以内的事务。

11 pointed   

adj.尖的，直截了当的

参考例句：

• He gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。
• She wished to show Mrs.John Dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。

12 component   

n.组成部分，成分，元件；adj.组成的，合成的

参考例句：

• Each component is carefully checked before assembly.每个零件在装配前都经过仔细检查。
• Blade and handle are the component parts of a knife.刀身和刀柄是一把刀的组成部分。

13 inhibit   

vt.阻止，妨碍，抑制

参考例句：

• Don't let ego and greed inhibit clear thinking and hard work.不要让自我和贪婪妨碍清晰的思维和刻苦的工作。
• They passed a law to inhibit people from parking in the street.他们通过一项法令以阻止人们在街上停车。

14 eradicate   

v.根除，消灭，杜绝

参考例句：

• These insects are very difficult to eradicate.这些昆虫很难根除。
• They are already battling to eradicate illnesses such as malaria and tetanus.他们已经在努力消灭疟疾、破伤风等疾病。

15 dispel   

vt.驱走，驱散，消除

参考例句：

• I tried in vain to dispel her misgivings.我试图消除她的疑虑，但没有成功。
• We hope the programme will dispel certain misconceptions about the disease.我们希望这个节目能消除对这种疾病的一些误解。