【英语生活】长命百岁，生活会变成什么模样？

In Jonathan Swift's 'Gulliver's Travels,' Gulliver encounters a small group of immortals, the struldbrugs. 'Those excellent struldbrugs,' exclaims Gulliver, 'who, being born exempt from that universal calamity of human nature, have their minds free and disengaged, without the weight and depression of spirits caused by the continual apprehensions of death!'

But the fate of these immortals wasn't so simple, as Swift goes on to report. They were still subject to aging and disease, so that by 80, they were 'opinionative, peevish, covetous, morose, vain, talkative,' as well as 'incapable of friendship, and dead to all natural affection, which never descended below their grandchildren.' At 90, they lost their teeth and hair and couldn't carry on conversations.

For as long as human beings have searched for the fountain of youth, they have also feared the consequences of extended life. Today we are on the cusp of a revolution that may finally resolve that tension: Advances in medicine and biotechnology will radically increase not just our life spans but also, crucially, our health spans.

The number of people living to advanced old age is already on the rise. There are some 5.7 million Americans age 85 and older, amounting to about 1.8% of the population, according to the Census Bureau. That is projected to rise to 19 million, or 4.34% of the population, by 2050, based on current trends. The percentage of Americans 100 and older is projected to rise from 0.03% today to 0.14% of the population in 2050. That's a total of 601,000 centenarians.

But many scientists think that this is just the beginning; they are working furiously to make it possible for human beings to achieve Methuselah-like life spans. They are studying the aging process itself and experimenting with ways to slow it down by way of diet, drugs and genetic therapy. They are also working on new ways to replace worn-out organs─and even to help the body to rebuild itself. The gerontologist and scientific provocateur Aubrey de Grey claims that the first humans to live for 1,000 years may already have been born.

The idea of 'conquering' aging has raised hopes, but it has also spurred a debate about whether people should actually aspire to live that long. What does a longer-living population mean for relationships and families? How can we afford to support massive numbers of aging citizens, and how can individuals afford to support themselves? Won't a society of centenarians just be miserable, tired and cranky?

The scientists working on these issues respond to such concerns by stressing that their aim is not just to increase the quantity of life but its quality as well. A life span of 1,000 may be optimistic, they suggest, but an average span of 150 years seems well within reach in the near future, with most of those years being vital and productive.

One key area of research is gene therapy. Cynthia Kenyon of the University of California, San Francisco, found that partially disabling a single gene, called daf-2, doubled the life of tiny worms called Caenorhabditis elegans. Altering the daf-16 gene and other cells added to the effect, allowing the worms to survive in a healthy state six times longer than their normal life span. In human terms, they would be the equivalent of healthy, active 500-year-olds.

Experiments with animals are not always applicable to humans, of course, but humans do have the same sort of genetic pathways that Dr. Kenyon manipulated. Other researchers have made similar findings. A laboratory at the University of Arkansas genetically altered worms to live 10 times longer than normal. Spain's National Cancer Research Center found an altogether different way to extend the lives of mice by 45%.

Other scientists are working to repair and replace worn-out body parts. The Wake Forest Institute for Regenerative Medicine, led by Anthony Atala, has successfully grown bladders in a lab and implanted them in children and teenagers suffering from a congenital birth defect. The basic structure of the bladders was built using biodegradable materials and was then populated with stem cells from the patients, so that their bodies wouldn't reject the transplant. It worked. Today the institute is working to grow more than 30 different organs and tissues, including livers, bone and hearts.

With heart disease the No. 1 killer in the U.S., building a human heart will be a major step forward. Doris Taylor announced in 2008 that her cardiovascular lab at the University of Minnesota had managed to grow a rat heart using a technique similar to Dr. Atala's, except that the structure she used was from a donor rat. Dr. Taylor is currently repeating the experiment on pigs, not only because their hearts are closer in size to human hearts but also because pig hearts are already used for replacement parts for some human heart patients.

Another promising new technology is organ printing, which is exactly what it sounds like: Cells, rather than ink, are put into a sophisticated 3-D printer and then printed onto a biodegradable material. The machine prints 'pages' of cells on top of each other to make a three-dimensional shape. In December 2010, a company called Organovo announced that it had successfully printed human blood vessels─an important feature of all organs.

At the McGowan Institute for Regenerative Medicine at the University of Pittsburgh, Stephen Badylak is working with 'extracellular matrix'─the material that gives structure to tissue─from pig bladders. Dr. Badylak has used ECM to grow back the tips of patients' fingers that have been accidentally snipped off, and his colleagues have used it to cure early-stage esophageal cancer by removing the cancerous cells and replacing them with ECM. Scientists don't yet understand why the substance promotes new tissue growth, and ECM can't yet grow back entire limbs, but the results so far are impressive.

Assuming that the necessary technology eventually arrives, the big question is: What will life look like when we live to over 100?

One of the most important areas of potential change is family and relationships. With an average life expectancy of 150 years, it's possible that we might see age differences of as much as 80 or 90 years between spouses and partners. But the historical evidence suggests that such disparities in age probably won't be common.

Research by Norway's government statistics bureau shows that between 1906 and 2002, life expectancy rose from around 57 years to around 79 years in that country. But the average age difference in relationships remained at around 3.5 years (men being slightly older).

One reason for the rarity of relationships with large age gaps is that modern societies tend to look down on them. Will the number of men marrying much younger women continue to grow as people live longer and such relationships become less stigmatized?

Research done at Stanford, the University of California, Santa Barbara, and the University of Wisconsin suggests that older men seek younger partners primarily to continue having children. If that is the case, such men won't need to find younger partners once it is easier for older women to have their own biological children using new fertility technologies.

And in the future, older women (and men) will likely look less 'aged' because they will remain healthy for much longer. Remarriage for beauty or youth will lose some of its distinguishing force.

More time to live also raises the possibility of more divorces and remarriages─the seven-year itch turned into the 70-year itch. Today, some people get married two or even three times, but as people live longer, these numbers could increase, perhaps exceeding Liz Taylor proportions for at least a small slice of the population. But greater longevity might also lead to a higher incidence of serial monogamy, regardless of whether it leads to marriage, perhaps interspersed with periods of living alone.

As researchers further refine reproductive technology like egg freezing and ovary transplants, the ranks of older parents, currently on the rise, are bound to increase even more. This raises the prospect of families in which siblings are born many decades apart, perhaps 50 years or more. How would such age gaps between children change family dynamics?

We know that siblings of the same age cohort have more meaningful and longer-lasting relationships than those separated by more years, but it is difficult to predict how the relationship between siblings born decades apart would function. It probably would be akin to that of a child and an aunt or uncle, or even a child and a grandparent.

Living longer would also mean both making and spending money longer. What would an economy look like in which work lives extended into a second century of potential productivity?

Most of us already don't expect to retire at 65. The Social Security system cannot afford it even now, and in the future, going out to pasture at 65 will mean decades of boredom. People who live to 150 will use their additional years for second and third careers, and we are likely to see a greater movement toward part-time and flex-time work.

It has long been clear that wealth creates health. We now know that health also begets wealth. In a paper titled 'The Health and Wealth of Nations,' Harvard economist David Bloom and Queen's University economist David Canning explain that, based on the available research, if there are 'two countries that are identical in all respects, except that one has a five-year advantage in life expectancy,' then the 'real income per capita in the healthier country will grow 0.3 0.5% per year faster than in its less healthy counterpart.'

Although these percentages might look small, they are actually quite significant, especially when we consider that between 1965 and 1990 countries experienced an average per capita income growth of 2% per year.

Those numbers are based on only a five-year longevity advantage. What if a country had a 10-, 20-, or 30-year advantage? The growth might not continue to rise in linear fashion, but if the general rule holds─a jump in life expectancy causes an increase in economic growth per capita─then having a longer-lived population would generate enormous differences in economic prosperity.

In a 2006 study, the University of Chicago economists Kevin Murphy and Robert Topel painstakingly calculated that for Americans, 'gains in life expectancy over the century were worth over $1.2 million per person to the current population.' They also found that 'from 1970 to 2000, gains in life expectancy added about $3.2 trillion per year to national wealth.'

The world's advanced societies are finally in a position to launch a true offensive against the seemingly irresistible terms imposed on our lives by disease and death. That's good news for us as individuals and for humanity as a whole. A longer span of healthy years will lead to greater wealth and prospects for happiness.

But realizing the full potential of the longevity revolution will not be easy. We will need to tackle important and legitimate questions about the effects of greater health spans on population growth, resource availability and the environment. The decisions that we make in this regard will matter far more than the mere fact of greater numbers.

The very idea of radically greater longevity has its critics, on the right and the left. Leon Kass, who served as chairman of the President's Council on Bioethics under George W. Bush, sees the scientific effort to extend life as an instance of our hubris, an assault on human nature itself.

The environmental writer Bill McKibben, for his part, strongly opposes what he calls 'techno-longevity,' arguing that 'like everything before us, we will rot our way back into the woof and warp of the planet.'

I'm unconvinced. Arguments against life extension are often simply an appeal to the status quo. If humans were to live longer, we are told, the world, in some way, would not be right: It would no longer be noble, beautiful or exciting.

But what is noble, beautiful and exciting about deterioration and decline? What is morally suspect about ameliorating human suffering?

The answer is nothing. Everything that we have, socially and as individuals, is based on the richness of life. There can be no more basic obligation than to help ourselves and future generations to enjoy longer, healthier spans on the Earth that we share.

Adapted from '100 Plus: How the Coming Age of Longevity Will Change Everything, From Careers and Relationships to Family and Faith' by Sonia Arrison.

F. Martin Ramin for The Wall Street Journal
在乔纳森·斯威夫特(Jonathan Swift)的小说《格列佛游记》(Gulliver's Travels)中，格列佛遇到了一小群被称为“斯特鲁德布鲁格”的长生不老之人。格列佛惊呼：“最幸福的还要算那些杰出的斯特鲁德布鲁格。他们从出生开始就不用受人类那共有的灾难，因为他们永远不怕死亡，所以心情舒畅，一点也不会感到心情沉重、精神萎靡。”

但是，随着斯威夫特的描述，我们看到这些长生不老之人的命运并非如此简单。他们也会衰老，也会疾病缠身，因此到了80岁左右，他们就会变得“性情顽固、暴躁、贪婪、沮丧、虚荣、多嘴，而且丝毫不讲友谊和情爱，即使有，顶多也只能对儿孙还有些感情。”到了九十岁，头发、牙齿全部脱落，连与人交谈都不能了。

人类一边仍在寻找长生不老泉，一边对寿命延长所带来的后果感到恐惧。如今，我们正处在一场革命的顶峰，这场革命可能最终解决这个让人紧张的问题：医药和生物技术的发展不仅将大大延长我们的生命年限，更关键的是，还将延长我们的健康年限。

高龄人口数量已经在增加。根据美国人口普查局(Census Bureau)公布的数据，美国年龄在85岁及以上的人口的数量约为570万，占人口总数的1.8%左右。按照目前的趋势，预计到2050年，这部分人口的数量将增至1,900万，占总人口的4.34%。那时候，美国百岁及百岁以上老人的数量占总人口的比重将从目前的0.03%升至0.14%，也就是说总共将有601,000位百岁以上老人。

但是，许多科学家认为，这不过是刚刚开始。他们正在全力以赴地工作，努力使人类能够像《圣经》中的玛士撒拉(Methuselah)一样高寿。他们正在研究衰老过程，并且通过控制饮食、服用药物和遗传疗法等方式对延缓衰老的方法进行试验。他们还在研究新的方法来替换衰竭的器官，甚至帮助人体自我重建。老年病学专家、科学狂人奥布里·德雷格(Aubrey de Grey)声称，第一个寿逾千岁的人可能已经出生了。

“征服”衰老这一理念给人类带来了希望，但也引发了关于人类是否真的应该追求如此长的寿命的争议。人口寿命的延长对婚姻关系和家庭意味着什么？我们怎么能养活如此多的老年人？每个人又该如何养活自己？一个满是百岁老人的社会难道不会让人觉得痛苦、厌倦而且诡异吗？

致力于解决长寿问题的科学家在回应这种关切时强调，他们的目标不仅仅是延长生命的长度，还要提高生命的质量。他们指出，寿逾千岁也许过于乐观了，但平均寿命达到150岁似乎是在不远的未来很有可能达到的目标，而且在这150年的大部分时间里，人们都能保持活力和生育能力。

基因疗法是一个关键的研究领域。美国加利福尼亚大学旧金山分校(University of California, San Francisco)的辛西娅·凯尼恩(Cynthia Kenyon)发现，在使一个单独的daf-2基因部分失效之后，一种名为秀丽隐杆线虫(Caenorhabditis elegans)的小蠕虫的寿命延长了一倍。改变daf-16基因和其他细胞可以增强长寿效果，使这种蠕虫在健康状态下存活的时间达到正常生命期限的6倍。就人类而言，这相当于健康、有活力地活到500多岁。

当然，动物试验并不一定都适用于人类，但是，人类身上确实存在凯尼恩博士改动过的那种基因调控机制。其他研究人员也有类似的发现。美国阿肯色大学(University of Arkansas)的一间实验室改变了蠕虫的基因，结果蠕虫的寿命比正常情况延长了10倍。西班牙国立癌症研究中心(National Cancer Research Center)通过研究发现了一种截然不同的方法，可以将老鼠的寿命延长45%。

R. Colman/Science/AAAS2009年的研究发现，通过限制热量似乎可以延缓猕猴衰老超过20年。如图所示，两只猕猴都是27岁。左边的那只（A，B）是吃的正常食物。而右边的猕猴（C，D）所吃食物的热量是被严格控制的，比正常食物要低30％，所以它看起来更年轻。还有一些科学家正在致力于修复和替换衰竭的人体器官。安东尼·阿塔拉(Anthony Atala)领导下的美国维克森林大学再生医学研究所(Wake Forest Institute for Regenerative Medicine)已经成功地在实验室中培育出了膀胱，并将其植入到存在先天性生理缺陷的儿童及青少年体内。人造膀胱的基本架构是用生物可降解材料制成的，然后用患者的干细胞进行繁殖，这样，患者的身体就不会排斥这个移植而来的器官。这项技术取得了成功。如今，这家研究所正在努力培育30多种器官和人体组织，包括肝脏、骨骼和心脏。

心脏病是美国第一大健康杀手，如果能培育出人造心脏，将是一项重大的进步。2008年，多丽丝·泰勒(Doris Taylor)曾宣布，她在美国明尼苏达大学(University of Minnesota)的心血管实验室采用一种类似于阿塔拉博士的技术培育出了一颗老鼠心脏，不同之处在于，她使用了一只供体老鼠的组织作为基础架构。泰勒博士目前正在猪身上重复进行这项试验，这不仅是因为猪心的大小接近人类心脏，还因为猪心已经被用来对某些心脏病患者进行心脏移植。

另一项很有前景的新技术是器官打印。顾名思义，器官打印就是将细胞（而不是油墨）装进尖端的3D打印机，然后在生物可降解材料上进行打印。这种机器能打印出一层层叠加的细胞，然后形成三维形状。2010年12月，一家名为Organovo 的美国生物技术公司宣布成功打印出人类血管，而血管是所有器官的一个重要组成部分。

美国匹兹堡大学(University of Pittsburgh)麦高恩再生医学研究所(McGowan Institute for Regenerative Medicine)的斯蒂芬·贝狄拉克(Stephen Badylak)正在研究能够为人体组织提供基本架构的“细胞外基质”(ECM)，这种材料取自猪膀胱。贝狄拉克博士已经利用ECM使患者意外折断的指尖重新生长出来，他的同事则通过移除癌细胞并代之以ECM来对早期食道癌患者进行治疗。科学家们还没有弄明白这种材料为什么能够促进新组织生长，而且ECM尚不能使整肢重生，但目前所取得的成果已经很令人振奋了。

假设长寿技术最终被人类所掌握，一个重要的问题是：当我们活到100多岁时，生活会变成什么模样？

可能发生变化的最重要领域之一就是家庭和婚姻关系。在人均寿命达到150岁的情况下，可能会出现配偶间年龄相差80岁或90岁的情况。但历史证据表明，这种年龄差距悬殊的情况可能不会很常见。

挪威政府统计局的研究显示，在1906年至2002年期间，该国的预期寿命从57岁左右延长至79岁左右。但是在婚姻关系中，平均年龄差距依旧保持在3.5岁左右（男性略微年长一些）。

年龄差距悬殊现象不常见的一个原因是现代社会一般看不起这种行为。随着人类寿命的延长，和比自己年轻许多的女性结婚的男性数量是否会增加？人们对这种关系的蔑视程度是否会减轻？

斯坦福大学、 美国加利福尼亚大学圣塔芭芭拉分校(University of California, Santa Barbara)和威斯康辛大学(University of Wisconsin)所做的研究表明，年长的男性寻找比较年轻的伴侣主要是为了继续生儿育女。如果情况果真如此，一旦年长的女性能够更容易地通过新的生殖技术孕育生物学意义上的子女，那么年长的男性就无需再去寻找较为年轻的伴侣了。

今后，年长的女性和男性可能看起来没有实际年龄那么老，因为他们保持健康状态的时间大大延长了。为了年轻或美丽而再婚的独特吸引力也将会下降。

寿命的延长还会使离婚和再婚的可能性增大，7年之痒会变成70年之痒。现在，有些人会结两次甚至三次婚，如果人们能活更长时间，这个数字可能会增加，至少会有少部分人的结婚次数超过伊丽莎白·泰勒(Liz Taylor)。但是，寿命的延长可能还会使“系列一夫一妻制”的现象增多，不一定每次都会结婚，也许在每段关系中间还会穿插独居的时期。

随着研究人员进一步完善卵子冷冻和卵巢移植等生殖技术，已经在不断壮大的高龄父母队伍势必将进一步扩大。这有可能使一个家庭中兄弟姐妹的年龄相差几十岁，也许相差50岁甚至更多。子女之间的这种年龄差距将会给家庭动力学特征带来什么样的改变？

众所周知，和年龄差距较大的兄弟姐妹相比，年龄相当的同胞之间能够维持更深厚、更长久的关系。但是，很难预测年龄相差几十岁的兄弟姐妹之间会保持一种怎样的关系。也许会类似于孩子和叔叔阿姨之间的关系，甚至像孩子和祖父母之间的关系。

寿命延长还意味着挣钱和花钱的时间也会延长。如果劳动寿命延长到一百年以上，经济看起来会是什么样？

我们当中的大部分人都已经不能指望在65岁退休了。即使是现在，社会保障体系就已经不堪重负了。今后，如果65岁就退休，将意味着还有几十年无所事事的光阴要打发。活到150岁的人们将利用多出来的时间展开第二次、甚至第三次职业生涯。我们可能会更多地转向兼职工作或弹性时间的工作。

人们早就知道，财富能增进健康。现在我们还知道，健康也会增进财富。哈佛大学(Harvard University)经济学家大卫·布卢姆(David Bloom)和加拿大皇后大学(Queen's University)经济学家大卫·坎宁(David Canning)在一篇题为《国民健康与财富》(The Health and Wealth of Nations)的论文中解释说，根据已有的研究，如果两个国家除了国民预期寿命相差5年之外其他各方面都完全一样，那么预期寿命较长的那个国家的实际人均收入的年增长率将比另一个国家高出0.3%-0.5%。

尽管这个百分比优势看起来不大，但实际上却会产生相当大的差异，尤其是考虑到1965年至1990年期间大多数国家的人均收入年增长率只有2%。

这些还只是根据预期寿命相差5年的前提得出的数据。如果一个国家在预期寿命方面存在10年、20年或者30年的优势呢？也许这种增长不会线性上升，但如果普遍规则成立（预期寿命的跃升会使人均经济增长率提高），那么国民寿命差距会给经济繁荣带来巨大的差异。

在2006年的一项研究中，芝加哥大学(University of Chicago)的经济学家凯文·墨菲(Kevin Murphy)和罗伯特·托佩尔(Robert Topel)花了很大的力气为美国人算了一笔账：一个世纪以来，预期寿命的延长给当前的人口带来了超过120万美元的人均价值。他们还发现，从1970年到2000年，预期寿命的延长使国民财富每年增长约3.2万亿美元。

如今，世界上最发达的一些国家终于已经准备好要对疾病和死亡加诸于人类身上的看似不可违逆的条款发起真正的攻势。不管是对我们个人还是对全人类来说，这都是个好消息。健康生命年限的延长将带来更大的财富和幸福的前景。

但是，要全面了解这场长寿革命的全部影响殊非易事。在健康生命年限的延长给人口增长、资源的可获得性和环境带来的影响方面，我们会有很多重要的问题和合法性问题需要解决。我们在这方面做出的决策所具有的意义要远远大于单纯的数字增长。

大幅延长人类寿命这一理念也招致了不少批评家的责难，其中既有右派人士也有左派人士。在乔治·W·布什(George W. Bush)政府担任过总统生物伦理委员会主席的利昂·卡斯(Leon Kass)认为，延长寿命的科学努力是人类狂妄自大的一个例证，是对人类本性的一种攻击。

环保作家比尔·麦吉本(Bill McKibben)认为这只不过是“技术性长寿”，并对此持强烈反对的态度。他认为，和人类面前的任何事物一样，我们都应该自然地枯萎腐烂，重新变成这颗星球上最基本的物质。

我对此不敢苟同。反对延长寿命的观点一般只是简单地要求保持原状。这种观点认为，如果人类活得更长，这个世界在某些方面就会变得不正常：不再那么高贵、美丽或激动人心。

但是，退化和衰败有什么高贵、美丽和激动人心可言呢？从道德角度来看，缓解人类的痛苦又有什么值得怀疑的呢？

答案是没有。无论是从社会角度还是个人角度来看，我们所拥有的每样东西都是建立在丰盛的生命这一基础上的。帮助我们自己和子孙后代在这个人类共同拥有的地球上生活得更长久、更幸福是一项最基本的责任。

本文改编自Sonia Arrison的新书 "100 Plus: How the Coming Age of Longevity Will Change Everything, From Careers and Relationships to Family and Faith"。