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Nothing seems more inevitable than aging and death, not even taxes. Every plant, animal and person you have ever seen will eventually die, including the person in the mirror. But some recent research suggests that aging as we know it may not be inevitable. Indeed, as our understanding of it grows, aging can be seen not as an immutable reality from which there is no escape, but as the product of biological processes that we may be able to control someday.
We already know that some animals do not seem to age. Many coldwater ocean fish, some amphibians and the American lobster never reach a feed size; they continue to grow bigger, to be able to reproduce and to live until something kills them. What these creatures seem to be telling us is that something in their genes—and possibly in ours-controls the pace of aging, and that aging is not the fate of every living thing.
Throughout the history of life on earth, one of the most common difficulties that animals (and their cells) have faced has been a lack of food. About 70 years ago, scientists discovered that when animals are forced to live on 30 to 40 percent fewer calories than they would normally eat, something unusual happens: they become resistant to most age-related diseases—cancer, heart disease, diabetes, Alzheimer's—and live 30 to 50 percent longer. Restricting calories slows aging.
But how? What are the underlying genes that preserve vitality and stave off disease? No one knows for sure why aging occurs, but one important reason is probably the accumulation of DNA damage-from radiation, mutation-causing chemicals or, particularly, oxidants. Inside every animal cell are many mitochondria-little "power packs" that use oxygen to generate energy. In doing their jobs, however, mitochondria produce chemical byproducts-oxidants-that damage DNA and other components inside cells. It may not seem fair, but it's a fact of life. Fortunately, our ceils are not defenseless against such assaults. They have genes that spring into action to defend against DNA damage, including genes that repair damaged mitochondria.
About 15 years ago, armed with powerful new molecular-research techniques, a few scientists began to investigate these genetic phenomena. At MIT, Dr.Leonard Guarente (along with one of the authors of this piece, David Sinclair) discovered that adding an extra copy of a gene called Sir2 caused yeast cells to live 30 percent longer. Today many researchers suspect that Sir2 or other sirtuin genes-which are present in all animals, including humans-are responsible for the health benefits of calorie restriction, perhaps by repairing our DNA. But if, in order to kick the sirtuins (一種蛋白質的名稱）into action, we had to restrict our calorie intake by 30 to 40 percent, would it be of any practical use? Few of us would be capable of restricting our diets so severely that we were constantly hungry: whether or not it made life longer, it would surely make life feel longer.
小試牛刀
1. In paragraph 1, author mentions aging and death to_______.
A. spotlight that aging and death are inevitable
B. state the fact that every creature will die
C. introduce the topic if we can control aging
D. show us that aging is the product of biological processes
2. We can conclude from paragraph 3 that _ .
A. some animals do not seem to age
B. when animals live on fewer calories, they will have more diseases
C. because of a lack of food, animals can live longer
D. getting more calories can slow aging
3. According to paragraph 4, which of the following statement is NOT true?
A. The accumulation of DNA damage which is from radiation, mutation has cause our aging
B. Inside every creature's cell, oxygen is used by mitochondria to generate energy.
C. Oxidants can damage DNA and other components inside cells.
D. Our cells can't resist the assaults, but they can repair damaged mitochondria.
4. What can we learn from the last sentence in paragraph 5?
A. Restricting our diets can make our life longer.
B. Life will be longer when we don't feel hungry any more.
C. It is still an unsure method for us to slow aging.
D. If we feel hungry constantly, we can surely live longer.
5. What is the author's purpose in writing this passage?
A. Explain the problem why death and aging are inevitable.
B. Analyse the reason why all creatures will eventually die.
C. Talk about whether we can slow aging.
D. Introduce how creature preserves vitality and stave off disease.
核心詞彙
accumulation [əˌkjumjəˈleʃən]
n. 積聚，堆積物
aging [ˈedʒɪŋ]
n. 老化，成熟的過程
amphibian [æmˈfɪbiən]
n. 丙棲動物
armed [ɑ:rmd]
adj. 有扶手的，武裝的， (動物）有防衛器官的
assault [əˈsɔlt]
n. 攻擊，襲擊
byproduct [ˈbaɪˌprɑdəkt]
n. 副產品
eventually [ɪˈvɛntʃuəli]
adv. 最後，終於
fate [fet]
n. 天數，命運，運氣
intake [ˈɪnˌtek]
n. 入口， 進口， 通風口， 引人的量
investigate [ɪnˈvɛstɪˌɡet]
v. 調查，研究
lobster [ˈlɑ:bstə(r)]
n. 龍蝦
mitochondria [ˌmaɪtoʊ'kɑ:ndrɪr]
n. [生] 線粒體
molecular [məˈlɛkjəlɚ]
adj. [化]分子 的，由分子組成的
pace [peɪs]
n. (—) 步，速度，步調，步法，步態
pack [pæk]
n. 包裹，背包，包裝
phenomena [fɪˈnɑmənə]
n. 現象
process [ˈproʊses]
n. 過程，作用，方法， 程序
resistant [rɪˈzɪstənt]
adj. 抵抗的，有抵抗力的
restriction [rɪˈstrɪkʃən]
n. 限制，約束
severely [səˈvɪrlɪ]
adv. 嚴格地，激烈地
underlying [ˌʌndərˈlaɪɪŋ]
adj. 在下面的，根 本的，潛在的，優先的
長難句解析
1. Indeed, as our understanding of it grows, aging can be seen not as an immutable reality from which there is no escape, but as the product of biological processes that we may be able to control someday.
結構分析： 本句是一個複合句。主句是aging can be seen not as...control someday, 同時其本身是一個並列句，but連接前後兩個小分句；as our understanding of it grows, 是一個as引導的時間狀語從句；aging can be seen...immutable reality是一 個被動句；from which引導一個定語從句，來修飾an immutable reality; that引導一個定語從句，來修飾biological processes。
參考譯文： 的確，隨著我們對老化的了解增多，我們認為老化並不是一個不能改變、無法逃避的現實，而是一種生化過程的產物，這一過程或許某一天能夠被我們控制。
2. About 70 years ago, scientists discovered that when animals are forced to live on 30 to 40 percent fewer calories than they would normally eat, something unusual happens.
結構分析： 本句是一個複合句。主句是About 70 years ago, scientists discovered;that後面引導一個賓語從句.來做discovered的賓語：when animals are forced... normally eat是一個由when引導的時間狀語從句，同時又是一個被動句；than they would normally eat是一個由than引導的部分省略的比較狀語從句。
參考譯文： 大約70年前，科學家發現當動物被迫攝入比正常生活需要少30%到40%的卡路裡時，一些奇怪的事情發生了。
3. Today many researchers suspect that Sir2 or other sirtuin genes—which are present in all animals,jncluding humans—are responsible for the health benefits of calorie restriction, perhaps by repairing our DNA.
結構分析： 本句是一個複合句。主句是Today many researchers suspect; that Sir2 or other... by repairing our DNA, 是that引導的一個賓語從句，來做suspect的賓語; which are present...humans是一個which引導的定語從句，來修飾Sir2 or other sirtuin genes, 同時其本身也是一個被動句；including humans是現在分詞短語作後置 定語，來修飾all animals.
參考譯文： 很多研究者懷疑Sir2基因或其他一些蛋白基因是通過對受損細胞的修復來達到這種效果的。
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