VOA英语2010年-Human Health Depends on Biodiversity

There's a good reason why people should be concerned about having a healthy environment containing lots of animal and plant species. A new study says the loss of biodiversity may make humans more vulnerable to infectious diseases.

Biodiversity is one of the ways to measure the health of an eco-system.  And the healthier an eco-system is, the better off we are. That's because animals, plants and even microbes can act as a buffer¹ between people and pathogens.

Associate Professor Felicia Keesing, an ecologist at Bard² College in Annandale, New York, is the lead author of the study.

"Biodiversity is the diversity of genes³, species and eco-systems that occupy the earth. Most of the time when we talk about biodiversity, we mean the diversity of species," she says.

Keesing says the study adds a new reason to protect the environment.

"People have always recognized that there's some sort of esthetic⁴ value in having all of these different creatures living on earth with us. Many people feel that there's an ethical⁵ responsibility to protect them. But in the last couple of decades, scientists have begun to document ways in which biodiversity is actually providing services to us. Such services become practical reasons for protecting biodiversity as well," she says.

It's long been known that biodiversity helps provide clean water, cycles nutrients⁶ through the eco-system, and absorbs carbon from the atmosphere. But Keesing says the fact that biodiversity protects humans from disease is a compelling reason for conservation.

Sucking up pathogens

Keesing says, "What we've seen over and over again in different studies that we describe in our paper is that in diverse systems the species that are present either reduce the number of disease bearing organisms by competing with them. Or they suck up pathogens, sort of vacuum up pathogens, and then don't transmit them again."

That protection suffers as biodiversity is lost. Keesing says one example is Lyme Disease, which is a common tick-borne bacterial⁷ illness in the United States.

"If you have a low diversity system, the species that are present always include white footed mice. And white footed mice are very, very good at transmitting the Lyme bacterium⁸ back out so that humans are at risk," she says.

Eco-systems under attack

Biodiversity faces many threats all over the world. The biggest, she says, is land conversion⁹.

"We're destroying habitats," she says, "So there are fewer places for organisms to live. But there are also a lot of other threats. The key ones are also climate change. So as the climate changes species are struggling and in some cases going extinct because they can't adapt quickly enough – or they have nowhere to go that has the appropriate environmental conditions."

Other threats to biodiversity include the spread of invasive species of plants and animals, as well as overhunting or overharvesting of species.

"In many ways, the biggest threat is that all of these things are happening at the same time and interacting with each other," she says.

Keesing rejects the idea that the loss of biodiversity is simply a matter of survival of the fittest, with humans being the most fit.

"Our survival," she says, "is actually linked to the survival of these other species. So, neither our short term nor our long term survival prospects¹⁰ are increased because we're destroying other species."

Scientists are also considering what a loss of biodiversity means for such diseases as Ebola in Africa. In other words, could it mean the disease could become more common and spread to new areas if there's a weak biodiversity buffer?

The Bard College associate professor says the effects of biodiversity loss are so clear, there's no reason to delay protecting the Earth's eco-systems.

1 buffer   

n.起缓冲作用的人(或物)，缓冲器；vt.缓冲

参考例句：

• A little money can be a useful buffer in time of need.在急需时，很少一点钱就能解燃眉之急。
• Romantic love will buffer you against life's hardships.浪漫的爱会减轻生活的艰辛。

2 bard   

n.吟游诗人

参考例句：

• I'll use my bard song to help you concentrate!我会用我的吟游诗人歌曲帮你集中精神！
• I find him,the wandering grey bard.我发现了正在徘徊的衰老游唱诗人。

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 esthetic   

adj.美学的，审美的；悦目的，雅致的

参考例句：

• That armchair is comfortable but not very esthetic.那张扶手椅坐起来舒服，但不太美观。
• There are physical distance and esthetic distance between the esthetic subject and the object.审美的主客体之间有物理距离和心理距离。

5 ethical   

adj.伦理的，道德的，合乎道德的

参考例句：

• It is necessary to get the youth to have a high ethical concept.必须使青年具有高度的道德观念。
• It was a debate which aroused fervent ethical arguments.那是一场引发强烈的伦理道德争论的辩论。

6 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• a lack of essential nutrients 基本营养的缺乏
• Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》

7 bacterial   

a.细菌的

参考例句：

• Bacterial reproduction is accelerated in weightless space. 在失重的空间，细菌繁殖加快了。
• Brain lesions can be caused by bacterial infections. 大脑损伤可能由细菌感染引起。

8 bacterium   

n.(pl.)bacteria 细菌

参考例句：

• The bacterium possibly goes in the human body by the mouth.细菌可能通过口进入人体。
• A bacterium is identified as the cause for his duodenal ulcer.一种细菌被断定为造成他十二指肠溃疡的根源。

9 conversion   

n.转化，转换，转变

参考例句：

• He underwent quite a conversion.他彻底变了。
• Waste conversion is a part of the production process.废物处理是生产过程的一个组成部分。

10 prospects   

n.希望，前途(恒为复数)

参考例句：

• There is a mood of pessimism in the company about future job prospects. 公司中有一种对工作前景悲观的情绪。
• They are less sanguine about the company's long-term prospects. 他们对公司的远景不那么乐观。