死亡率模式保持不變 何必爲長壽煩惱

In developed countries today life expectancy at birth is about 80 years. That figure has almost doubled over the past century. Life expectancy at birth measures how long someone born today would survive if the patterns of mortality existing when they were born continued through their lifetime. But they will not.
在發達國家，現在出生的人預期壽命約爲80歲。這個數字在過去的1個世紀裏幾乎翻了一番。人在出生時的預期壽命衡量的是，現在出生的人，如果他們出生時整個社會的死亡率模式在他們一生中保持不變，那麼他們的壽命是多久。但死亡率模式不會保持不變。

These patterns improve, so that most people born in the past century have lived far beyond their life expectancy at birth. Children born today can expect to live well beyond 80 years, even if the claim by Peter Thiel and Aubrey de Grey that the first 1,000-year man is already alive is optimistic.
死亡率模式在不斷改善，因此，過去一個世紀中出生的大部分人活着的時間，已經遠遠超出了他們出生時的預期壽命。即便企業家彼得•蒂爾(Peter Thiel)和學者奧布里•德格雷(Aubrey de Grey)宣稱第1個能活到1000歲的人已經出現的說法過於樂觀，但可以預計，今天出生的兒童的壽命將遠不止80歲。

Life expectancy was much lower a century ago because many children died in infancy and many adults failed to achieve a normal lifespan because they were killed by now-curable infectious diseases. Deaths from these sources are now so low that even dramatic further improvements will not have much effect on average lifespan. The most important factor today is increases in life expectancy after conventional ages of retirement. This measure has recently been improving at one to two months a year.
一個世紀以前，預期壽命比現在低得多，因爲當時嬰兒夭折率很高，許多現在我們已經能夠治癒的傳染性疾病又提前奪去了許多成年人的生命。現在因這些原因死亡的人數很少，以至於即使在這方面出現巨大的進步，也不會顯著提高平均壽命。如今最重要的因素是，預期壽命減去通常退休年齡後所餘時間的增長。近年來這項指標每年提高1到2個月。

Life-saving advances are the greatest benefit of technological change. And yet when pundits discuss the future, the excitement around driverless cars and nanotechnology gives way to long faces when the topic moves to human longevity. It may be nice to live longer, but what about the effect on the economy? The question is absurd. Economic growth is about giving people more choices, and no choice is more earnestly sought than the chance of a longer life. The hard economic evidence is the amount that people are willing to pay to extend their lives even for short periods.
技術變革帶來的最大福祉就是生命救助方面的技術進步。然而同樣是在展望未來，專家們談論起無人駕駛汽車和納米技術時一臉興奮，話題轉到人類長壽時他們卻拉長了臉。長壽固然好，但是這對經濟的影響該怎麼辦呢？這個問題是荒謬的。經濟增長的目的是給人們更多選擇，而沒有什麼選擇能比有機會延年益壽更讓人魂牽夢繞了。爲了延長壽命，哪怕只是很短的時間，人們也願意花很多錢，這就是經濟上的鐵證。The demographic “crisis” has several components. There is the cost of pensions. Someone born today, retiring at 60 and living to 100, would have equal spells of work and retirement. Society is moving towards the obvious resolution – a concept of flexible retirement in which people can choose their preferred trade-off between work and leisure.
這個人口統計學上的“危機”有幾個組成部分。養老金費用是其中之一。現在出生的人，如果60歲退休、活至100歲，那麼退休後的時間就和工作的時間一樣長了。社會正趨向顯而易見的解決方式——彈性退休制，讓人們可以在工作和退休間自由權衡。

Achieving these extended lifespans costs money. Not necessarily much, because healthy lifestyle is a more important contributor to longevity than medical treatment. But we all die, either from the remaining diseases we have not yet learnt to cure, or the accumulated effects of old age itself. So medical and care costs will inevitably be an increasing fraction of national income. But this is money the public really wants to spend. It resists attempts to control the grotesque costs of private US healthcare. “More for the National Health Service” is always the British electorate’s top spending priority.
實現壽命的延長要花錢。並不一定需要很多錢，因爲就長壽而言，健康的生活方式比醫療保健更重要。但人都不免一死，要麼死於那些我們還不知道如何治癒的絕症，要麼死於年老本身帶來的累積效應。因此，醫療和護理費用在國民收入中的比重將不可避免地上升。然而這份錢是公衆確實想花的。美國控制私人醫療保健極高費用的嘗試遭到了公衆的抵制。“多向國民醫療服務體系(NHS)投入”一直都是英國選民對政府支出的頭號要求。

Then there is the burden of an ageing population on a younger workforce. Here we are caught in a squeeze between the growing numbers of the elderly and a lower birth rate. In Europe today, the median age at which women have their first child is over 30. But we do not know whether these women, pursuing careers before starting a family, will ultimately have fewer children or just later children: completed family size is the key variable.
其二是老齡化人口對青壯年勞動力造成的負擔。我們面對老齡人口日益增長和出生率降低的兩頭夾擊。在當今的歐洲，女性生育第1胎的年齡中值超過了30歲。但是我們不知道這些先立業後生育的女性，最終將生育更少的孩子，還是僅僅選擇晚生孩子：最終家庭中人口的數量纔是關鍵變量。

Prediction is hard, especially about the future. Gloomy prognostications, sometimes of population explosion, then of secular stagnation, have repeatedly been falsified. But one certainty is that all the issues of concern result from developments that give us more choices – the choice between higher material living standard and more leisure, the indulgence of spending more looking after ourselves, and the opportunity for women to have careers as well as, or along with, family lives.
預測本來就很難，預測未來就更難了。那些悲觀的預言，一會兒是人口爆炸一會兒是長期經濟停滯，已經一次又一次的被證僞了。但有一點是肯定的，那就是所有這些令人擔心的問題都是由一些新動向帶來的，這些新動向讓我們擁有了更多選擇——是要更高的物質生活水平還是要更多的閒暇時間，要不要盡情花更多錢用於健康護理，女性也有了兼顧事業和家庭（或是在家庭之外也擁有一份事業）的機會。

What is not to like about these developments? Why should we care about lower gross domestic product per capita, or higher public spending as a share of national income if it is the consequence of things that make us better off?
這些新動向哪一點不好？如果人均國內生產總值(GDP per capita)沒那麼高或者公共支出佔國民收入比重上升只是因爲我們的生活變得更好了，我們又何須憂慮呢？