科普類英語文章

　　隨著科學技術的飛速發展和全球化程序的不斷加快，科普文章在向社會大眾普及科學技術知識，提高公眾科學素養等方面發揮著舉足輕重的作用。下面是小編帶來的，歡迎閱讀!

　　生物與環境平衡的危機

　　The history of life on earth has been a history of interaction between living things and their surroundings. To a large extent, the physical form and the habits of the earth’s vegetation and its animal life have been molded by the environment. Considering the whole span of earthly time, the opposite effect, in which life actually modifies its surroundings, has been relatively slight. Only in the present century has one species man acquired significant power to alter the nature of his world.

　　During the past quarter century this power has not only become increasingly great but it has changed in character. The most alarming of all man’s assaults upon the environment is the contamination of air, earth, rivers, and sea with dangerous and even lethal materials. This pollution is for the most part irrecoverable. In this now universal contamination of the environment, chemicals are the sinister partners of radiation in changing the very nature of the world the very nature of its life. Chemicals sprayed on croplands or forests or gardens lie long in soil, entering into living organisms, passing from one to another in a chain of poisoning and death. Or they pass mysteriously by underground streams until they emerge and combine into new forms that kill vegetation, sicken cattle, and work unknown harm on those who drink from once pure wells. "Man can hardly even recognize the devils of his own creation," as a scientist has said.

　　It took hundreds of millions of years to produce the life that now inhabits the earth. Given time not in years but in millennia life adjusts, and a balance has been reached. But in the modern world there is no time.

　　The rapidity of change follows the impetuous pace of man rather than the deliberate pace of nature. Radiation is now the unnatural creation of man’s tampering with the atom. The chemicals are the synthetic5 creations of man’s inventive mind, having no counterparts in nature.

　　To adjust to these chemicals would require not merely the years of a man’s life but the life of generations. And even this, were it by some miracle possible, would be futile, for the new chemicals come from our laboratories in an endless stream; almost five hundred annually find their way into actual use in the United States alone. Among them are many that are used in man’s war against nature. Since the mid 1940’s over 200 basic chemicals have been created for use in killing insects, weeds, and other organisms described as "pests."

　　It is not my contention that chemical insecticides must never be used. I do contend that we have put poisonous and biologically potent chemicals indiscriminately into the hands of persons largely or wholly ignorant of their potentials for harm. We have subjected enormous numbers of people to contact with these poisons, without their consent and often without their knowledge. I contend, furthermore, that we have allowed these chemicals to be used with little or no advance investigation of their effect on soil, water, wildlife, and man himself. Future generations are unlikely to forgive our lack of concern for the integrity of the natural world that supports all life.

　　地球上生命的歷史一直就是一部生物與其環境相互作用的歷史。在很大程度上，地球上動植物的形態以及習性都是由外部環境所塑造的。考慮到地球上生命存在的整個時間，相反作用，即生命對其周圍環境的實際改變作用，卻相對很小。只有在當前這個世紀指20世紀才有一個物種--人類，獲得了強大的力量，改變了其所生存的世界的自然狀態。

　　在過去的1/4世紀中，這種力量不僅日趨強大，而且其性質也發生了變化。在人類破壞環境的種種行為中，最令人擔憂的是人類向大氣、土壤、河流以及海洋中排放危險甚至致命物質，而當今這種汙染在很大程度上是無法挽救的。在當今這種對環境的普遍汙染中，化學制品與輻射狼狽為奸，改變著地球的自然狀態，也就是改變著地球上生命的自然狀態。噴灑到農田、森林或者花園裡的化學物質長期滯留於土壤中，滲入有機體內，並彼此相傳，形成了一箇中毒與死亡的鏈條。化學物質還神祕地通過地下水傳遞，最終以新的形式出現並結合，使植物毒死，牲畜害病，並使飲用一度純淨的井水的人遭受了不明之害。正如一位科學家所言：“人類甚至對自己創造的惡魔都不認識。”

　　地球歷經了許多億年才創造了棲息其上的生命。經過了一定時間--不是以若干年計而是以若干千年計的時間--生命開始適應環境，並形成了一種與環境的平衡。但是在現代世界中，時間這一因素已經沒有了。

　　環境改變的速度不再順從大自然從容不迫的節奏，而是順從人類急切匆匆的步伐。輻射是當今人類通過支配原子而得到的一種非自然的創造物。化學制品則是人類有發明創造力的頭腦創造出來的合成物，在自然界本無相應的東西。

　　為了適應這些化學制品，人類需要付出的時間不會只是一個人一生的時間，而是幾代人的時間。而即使這樣，就算出現奇蹟成為可能，這種適應也是徒勞的，因為新的化學制品從我們的實驗室中源源不斷地湧出。僅在美國，每年就有大約500種化學制品投入使用，其中許多是用於人類對自然的戰爭中。從20世紀40年代中期起，人類已經創造了200多種基本化學制品用來消滅昆蟲、野草以及其他所謂的“有害生物”。

　　我不是說人類決不能使用化學殺蟲劑。我要說的是，我們不分青紅皁白地將這些有毒的、具有強大生物功能的化學制品，交給了那些對這些製品的潛在危害基本上或者完全無知的人去使用。我們使眾多的人接觸這些有毒物質，卻沒有徵得他們的同意，並常常將他們蒙在鼓中。我還要說的一點是，我們允許使用這些化學制品，卻事先很少或者根本沒有調查它們對土壤、水、野生生物以及人類自身造成的影響。我們缺乏對萬物賴以生存的自然界生態統一的關心，對此，我們的後代是不可能原諒的。

　　基因技術能否使人更聰明?Get Smart

　　Many people dream of having a smarter brain. Princeton neurobiologist Joseph Z. Tsien found the key. In September he announced that he’d built a better mouse by altering a gene that affects learning and memory. A similar process of gene manipulation might conceivably be used one day to boost intelligence in humans.

　　The secret lies in a feature of brain cells called the nmda receptor, which Tsien likens[1] to a cylindrical tube or window that mediates[2] the flow of information. When the window is open, chemicals called neurotransmitters flow through easily and memory is registered and stored. But as organisms mature, the window begins to close. This may explain why children lose their facility for learning new languages when they reach sexual maturity and why some people suffer memory loss as they age.

　　Tsien noticed that the receptor worked more efficiently when teamed[3] with the gene NR2B, so he introduced extra NR2B genes into a batch of fertilized mouse eggs. In a normal mouse, the memory window is open for just 150-thousandths of a second. In Tsien’s specially engineered mice, the window opens for 250-thousandths of a second, long enough to make a remarkable difference in memory retention. When he pitted[4] his mice against common mice, they won paws down. Ordinary mice could recognize a Lego block for 12 hours, but smart mice could remember the block for up to three days. "That’s a profound enhancement," Tsien says.

　　Can it be done with humans? Maybe, but genetic engineering will have to make some extraordinary advances first. And some thorny ethical issues will have to be resolved. Meanwhile, Tsien promises to keep his furry little geniuses locked up in a lab, far from your larder. "Otherwise," he says, "you might need a smart cat or a smart mousetrap to catch them."

　　許多人都希望自己能變成更聰明。普林斯頓神經生物學家Joseph Z. Tsien就找到了這把開啟智慧之門的鑰匙：他於九月宣佈，通過改變影響學習和記憶能力的基因培養出了一隻聰明的老鼠。類似的基因處理技術有望在未來日子裡運用到人腦，以推動人類智慧的飛躍。

　　該技術的奧祕就在於名為nmda感受器的腦細胞的功能。Tsien將其比作一個傳遞資訊流的圓柱通道或視窗。當視窗開放時，某種稱為神經傳遞素的化學物質就能輕易流過，記憶因此登記並存儲了下來。然而，當器官成熟時，這扇視窗就開始關閉。這也能解釋為何兒童長大後性器官成熟之時會失去掌握新語言的能力，以及為何某些人年老時會患失憶。

　　Tsien注意到，當感受器與名為NR2B的基因協作時效率會更高。因此，他將NR2B基因植入一批老鼠的受精卵中。一隻普通老鼠的記憶之窗僅開放千分之150秒。而經Tsien植入基因的老鼠，記憶之窗能開放千分之250秒，這已經能夠使其記憶力發生驚人的改變。當他讓自己的老鼠與普通老鼠互鬥時，它們竟能輕而易舉地取勝。普通老鼠能夠保留關於Lego block的記憶12小時，而聰明的老鼠居然能將記憶保持三天。“這可是一個意義深遠的進步。”Tsien這樣說。

　　那麼，人類也能接受這種基因移植嗎? 或許可以，但前提是基因工程得首先做出非凡的成就，還必須解決一系列棘手的倫理問題。Tsien保證他一定會將那些披著毛皮的小天才鎖入實驗室，遠離人們的食品櫃。“否則，”他說，“為了捉住他們，人們就不得不去尋找更聰明的貓或者功能更強的捕鼠器了。”

　　食用轉基因食品安全嗎?Food Safe To Eat?

　　Traditional plant breeding involve s crossing varieties of the same species in ways they could cross naturally.For example，disease-resistant varieties of wheat have been crossed with high-yield wheat to combine these properties.This type of natural gene exchange is safe and fairly predictable.

　　Genetic engineeringGEinvolves exchanging genes between unrelated species that cannot naturally exchange genes with each other.GE can involve the exchange of genes between vastly different species――e.g.putting scorpion toxin genes into maize or fish antifreeze genes into tomatoes.It is possible that a scorpion toxin gene，even when it is in maize DNA，will still get the organism to produce scorpion toxin――but what other effects may it have in this alien environment?We are already seeing this problem――adding human growth hormone genes to pigs certainly makes them grow――but it also gives them arthritis and makes them cross-eyed，which was entirely unpredictable.

　　It will be obvious，for example，that the gene for human intelligence will not have the same effect if inserted into cabbage DNA as it had in human DNA――but what side-effect would it have?In other words，is GM food safe to eat?The answer is that nobody knows because long-term tests have not been carried out.

　　Companies wanting a GM product approved in the UK or USA are required to provide regulatory bodies with results of their own safety tests.Monsanto’s soya beans were apparently fed to fish for10weeks before being approved.There was no requirement for independent testing，for long-term testing，for testing on humans or testing for specific dangers to children or allergic people.

　　The current position of the UK Government is that“ There is no evidence of long-term dangers from GM foods.”In the US，the American Food and Drug Administration is currently being prosecuted for covering up research that suggested possible risks from GM foods.

　　傳統的植物培育方法，是依照植物自然雜交的方式，進行相同物種的人工雜交。比如，抗病小麥同高產小麥雜交，形成了一種具有雙重特性的新的小麥品種。這種自然的基因交換既安全，又具有相當的可預見性。

　　基因工程是在彼此毫無關係的物種之間，相互交換在自然條件下無法交換的基因。它可在有巨大差異的物種之間進行基因交換。比如，將蠍子毒素基因注入玉米，或者將魚防凍基因注入西紅柿。即使在玉米DNA中，蠍子毒素基因依然可能獲得有機組織產生蠍子毒素。但是在這種異質的環境中，這種基因產品會有什麼其他作用嗎?我們實際上已經發現這個問題：將人類生長荷爾蒙基因植入豬的體內，一定會使豬的生長加速，但是同時也使豬患上了關節炎和內斜視，而這一切是完全無法預測的。

　　打個比方，人類的智力基因顯而易見在人體DNA內和注入捲心菜DNA後的作用是不同的。但將它植入捲心菜中會產生什麼樣的副作用呢?換句話說，食用轉基因食品安全嗎?沒有人知道答案，因為人們尚未進行長期的測試。

　　在英國或者美國，一個公司如果希望其轉基因產品獲得批准，它必須向管理機構提供本公司轉基因產品安全測試的結果。Monsanto的大豆在獲得批准之前，曾用了10周時間進行餵魚試驗。目前，尚無要求對轉基因產品進行獨立測試、長期測試、人體測試，或者就其對兒童及過敏者所造成的特定危險進行測試。

　　英國政府目前的態度是：“尚無證據表明食用轉基因食品存在長期性的危險。”在美國，人們正在起訴美國食品藥品管理局掩蓋轉基因食品安全性的研究結果，這些研究結果表明，食用轉基因食品可能導致危險。