弃我去者, 弃我去者,昨日之日不可留 乱我心者, 乱我心者,今日之日多烦忧
>80 Evolution and Wheels In the past, evolutionary biologists contemplating the absence of wheels in nature agreed that the explanation was not undesirability: wheels would be good for animals, just as they are for us. Animals were prevented from evolving wheels, the biologists reasoned, by the following dilemma: living cells in an animal's body are connected to the heart by blood vessels, and to the brain by nerves. Because a rotating joint is essential to a wheel, a wheel made of living cells would twist its artery vein and nerve connections at the first revolution, making living impracticable. However, there is a flaw in the argument that the evolution of wheeled animals was thwarted by the insoluble joint problem. The theory fails to explain why animals have not evolved wheels of dead tissue with no need for arteries and nerves. Countless animals, including us, bear external structures without blood supply or nerves - for example, our hair and fingernails, or the scales, claws, and ho rns of other animals. Why have rats not evolved bony wheels, similar to roller skates? Paws might be more useful than wheels in some situations, but cats' claws are retractable: why not retractable wheels? We thus arrive at the serious biological paradox flippantly termed the RRR dilemma: nature's failure to produce rats with retractable roller skates. 进化与轮子 从前, 研究自然界没有轮子的进化论生物学家都同意不能用无此需要来解释这种现象: 轮子 对于动物会像对于我们人类一样有好处。 生物学家们推论,动物没有进化出轮子是由下述 困难所致:动物身上的活细胞通过血管与心脏相连,通过神经与大脑相连。 因为一个旋转 的接头对轮子来说是至关重要的, 由活的细胞构成的轮子在第一次转动时便会扭伤其上的动 脉和神经的连结,因而不现实。 不过,动物未能进化出轮子是受阻于无法解决接头问题的说法有一个缺陷。 这种理论无法 解释为何动物没有进化出由死组织构成的而无需动脉和神经的轮子。 包括人在内的无数动 物都有一些没有血液供应和神经的体外构造,例如,我们的头发和指甲,或者鳞片、爪子和 其它一些动物的角。为什么老鼠没有进化出类似于滑轮溜冰鞋的骨质的轮子呢?在某些情况 下,爪子可能比轮子更有用,但猫的爪子是可以伸缩的: 为什么不能有可以伸缩的轮子呢? 这样,我们便得出了一个被戏称为 RRR 的严肃的生物学悖论:大自然未能产生出有可伸缩 的滑轮溜冰鞋的老鼠。
>79 Population Growth The growth of population during the past few centuries is no proof that population will continue to grow straight upward toward infinity and doom. On the contrary, demographic history offers evidence that population growth has not been at all constant. According to paleoecologist Edward Deevey, the past million years show three momentous changes. The first, a rapid increase in population around one m illion B. C., followed the innovations of tool making and tool using. But when the new power from the use of tools has been exploited, the rate of world population growth fell and became almost stable. The next rapid jump in population started perhaps 10,000 years ago, when mankind began to keep herds, plow and plant the earth. Once again when initial productivity gains had been absorbed, the rate of population growth abated. These two episodes suggest that the third great change, the present rapid growth, which began in the West between 250 and 350 years ago, may also slow down when, or if, technology begins to yield fewer innovations. Of course, the current knowledge revolution may continue without foreseeable end. Either way - contrary to popular belief in constant geometric growth - population can be expected in the long run to adjust to productivity. And when one takes this view, population growth is seen to represent economic progress and human triumph rather than social failure. 人口增长 以往几个世纪人口的增长并不能证明人口会无限地直线向上增长直到毁灭的地步。 相反地, 人口统计史料证明人口的增长完全不是稳定的。 古生态学家爱德华?狄维认为, 在过去 100 万年间出现过 3 次重大的变动。 第一次在公元前 100 万年左右, 随着在工具的制作和使用 上的革新而出现人口迅速增长。 但当工具的使用所产生的新动力被充分利用以后,世界人 口增长率下降并且趋于稳定。 第二次人口剧增大约始于人类开始蓄畜、垦耕的
  10,000 年前。 一旦最初的生产力增长被吸收殆尽,人口的增长再次衰落。 以上两段说明,若技术 革新的成果开始减少, 250 到 350 年前就在西方开始出现的并且目前还在继续的人口迅 从 速增长可能也会放慢。 当然,当前的知识革命也许会持续下去而无法预见其末来。 无论如 何,与那种认为人口以几何级数持续增长的观点相反,从长远的观点来说,人口可望受到生 产力的调节。 接受了这一观点,人口的增长就可以被看成是经济进步和人类胜利的标志,
而不是社会衰败的标志。
>78 Police and Communities Few institutions are more important to an urban community than its police, yet there are few subjects historians know so little about. Most of the early academic interests developed among political scientists and sociologists, who usually examined their own contemporary problems with only a nod toward the past. Even the public seemed concerned only during crime waves, periods of blatant corruption, or after a particularly grisly episode. Party regulars and reformers generally viewed the institution from a political perspective; newspapers and magazines - the nineteenth century's media - emphasized the vivid and spectacular. Yet urban society has always vested a wide, indeed awesome, responsibility in its police. Not only were they to maintain order, prevent crime, and protect life and property, but historically they were also to fight fires, suppress vice, assist in health services, supervise elections, direct traffic, inspect buildings, and locate truants and runaways. In addition, it was assumed that the police were the special guardians of the citizens' liberties and the community's tranquillity. Of course, the performance never matched expectations. The record contains some success, but mostly failure; some effective leadership, but largely official incompetence and betrayal. The notion of a professional police force in America is a creation of the twentieth century; not until our own time have cities begun to take the steps necessary to produce modern departments. 警察与社区 对城市社区来说, 很少有比它的警察更为重要的机构了, 但少有课题像历史学家们对此了解 得那样少。 早期的学术兴趣是在政治科学家和社会学家中发展起来的,他们一般只研究他 们自己当代的问题而对过去的问题只是偶尔带过。 甚至公众似乎也仅仅在犯罪浪潮、明目 张胆的贪污或特别的恐怖事件发生时才关心。 政党的忠诚支持者和改革家们通常是从政治 的前途来看待警察这个机构;而报纸和杂志-19 世纪的传播媒介-则着重活泼生动和惊人的 事件。 可是城市社会总是把广泛得可怕的责任交给警察。 他们不仅维持秩序、防止犯罪、 保护生命财产,而且在过去还要救火、镇压罪恶、协助医疗服务、监督选举、指挥交通、检 查建筑物、寻找逃学学生和搜捕逃犯。 除此以外,警察还被认为是公民自由和社会稳定的
特别保护者。 自然, 警察的表现并不尽如人意。 他们的记录中有成功者, 但多数是失败的; 有高效率的领导,但多半的人在职务上无能和不讲信用。 专业警察部队的概念在美国还是 20 世纪的产物;直到我们这个时代,一些城市才开始采取设立现代化部门的必要步骤。
>77 Food and Health The food we eat seems to have profound effects on our health. Although science has made enormous steps in making food more fit to eat, it has, at the same time, made many foods unfit to eat. Some research has shown that perhaps eighty percent of all human illnesses are related to diet and forty percent of cancer is related to the diet as well, especially cancer of the colon. Different cultures are more prone to contract certain illnesses because of the food that is characteristic in these cultures. That food is related to illness is not a new discovery. In 1945, government researchers realized that nitrates and nitrites, commonly used to preserve color in meats, and other food additives, caused cancer. Yet, these carcinogenic additives remain in our food, and it becomes more difficult all the time to know which things in the packaging labels of processed food are helpful or harmful. The additives which we eat are not all so direct. Farmers often give penicillin to beef and poultry, and because of this, penicillin has been found in the milk of treated cows. Sometimes similar drugs are administered to animals not for medicinal purposes, but for financial reasons. The farmers are simply trying to fatten the animals in order to obtain a higher price on the market. Although the Food and Drug Administration (FDA) has tried repeatedly to control these procedures, the practices continue. 食品与健康 我们所吃的食物似乎对我们的健康有深远的影响。 尽管科学上已取得许多进展,使食物更 适合我们食用,但与此同时它也使许多食物不宜食用了。 一些研究已经表明,人类大概有 80%的疾病与饮食有关,40%的癌症,特别是结肠癌,也与饮食有关。 不同的文化会使 人们更易患某些疾病,这是由这些文化的人们喜好的食物所致。 食物与疾病有关并不是新 发现。 1945 年,政府部门的科研工作者了解到,被广泛用于肉类以保持肉类色泽的硝酸 盐、 亚硝酸盐和其他的添加剂可诱发癌症。 可是这些致癌物质依然存在于我们的食物之中。 与此同时,要想知道加工食品标签上的哪些成分对健康有利,哪些成分对健康不利,变得更 加困难了。 我们吃到的这些添加物并非都是如此直接的。 农民常给牛和家禽注射青霉素, 因而在受过注射的牛所产牛奶里发现青霉素。 有时让家禽服用这类药物并非是为了治病,
而是为了经济上的缘故。 农民们只是想使家畜长得更肥壮可以上市场上卖到好价钱。 虽然 食物和药品管理局已一再设法控制这种情况的发生,但是这种行为仍在继续。
>76 MARS Mars According to the best evidence gathered by space probes and astronomers, Mars is an inhospitable planet, more similar to Earth's Moon than to Earth itself - a dry, stark, seemingly lifeless world. Mars' air pressure is equal to Earth's at an altitude of 100,000 feet. The air there is 95% carbon dioxide. Mars has no ozone layer to screen out the Sun's lethal radiation. Daytime temperatures may reach above freezing, but because the planet is blanketed by the mere wisp of an atmosphere, the heat radiates back into space. Even at the equator, the temperature drops to 50℃ ( 60 ) at night. Today there is no liquid water, although valleys and channels on the surface show evidence of having been carved by running water. The polar ice caps are made of frozen water and carbon dioxide, and water may be frozen in the ground as permafrost. Despite these difficult conditions, certain scientists believe that there is a possibility of transforming Mars into a more Earth like planet. Nuclear reactors might be used to melt frozen gases and eventually build up the atmosphere. This in turn could create a "greenhouse effect" that would stop heat from radiating back into space. Liquid water could be thawed to form a polar ocean. Once enough ice has melted, suitable plants could be introduced to build up the level of oxygen in the atmosphere so that, in time, the planet would support animal life from Earth and even permanent human colonies. "This was once thought to be so far in the future as to be irrelevant," said Christopher McKay, a research scientist at the National Aeronautics and Space Administration. "But now it's starting to look practical. We could begin work in four or five decades." The idea of "terra forming" Mars, as enthusiasts call it, has its roots in science fiction. But as researchers develop a more profound understanding of how Earth's ecology supports life, they have begun to see how it may be possible to create similar conditions on Mars. Don't plan on homesteading on Mars any time soon, though. The process could take hundreds or even thousands of years to complete, and the cost would be staggering. 火星 据宇宙探测器和天文学家收集的有力证据, 火星是一个人类不能居住的星球。 它不像地球, 而更像月球--一个干涸、荒芜,看上去没有任何生命的世界。 火星的气压相当于地球上十 万英尺高空处的气压。 火星大气的构成中有 95%是二氧化碳,而且,火
 

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