朴敏晶的碩士論文："柳永與蘇軾的歌妓詞研究" (韓文，2012)。讀書中的中文，知道韓國有柳永的碩士論文5篇；蘇東坡博士論文2篇等等。孫康宜的英文著作和兩岸的譯本、錢鍾書的"宋詩選註"有韓譯.....《樂府餘論》說柳詞”一時動聽，散佈四方，東坡、少游輩繼起，慢詞遂盛。 ” ......
10月初，美國愛因斯坦醫學院的團隊利用人口學資料發現了人類壽命的大限，成了新聞。其實這不該是新聞，因為生物壽命有自然大限，是經驗事實，是常識。可是我們從小背誦的樂觀說詞，例如科學發達、醫藥昌明，卻讓我們忽略了經驗與常識。
人的平均壽命，或者說人出生時的壽命期望值，已經大幅上升，是事實。在20世紀，平均壽命幾乎增加了一倍：從40歲到80歲，因此現在每個人都預期自己或他人會活到七老八十。這個成就是大家熟知的因素造成的，包括環境衛生、醫藥保健、飲食營養。結果，幼年人口的存活率大幅提升，平均壽命增加。
那麼科技的進步，特別是生物醫學，會不會繼續提升我們的壽命呢？人口學資料顯示，推升平均壽命的力量在1980年代便已進入高原期：高齡人口的存活率並沒有繼續上升，而且到了100歲便陡然下降。
另一方面，人的絕對壽命（死亡年齡）也沒有上升。已知最長壽的人是法國婦人金‧卡芒（Jeanne Calment, 1875-1997），她活了122歲，20年來還無人超越。人的絕對壽命已經停滯了20年！
老聃曰：「人生天地之間，若白駒之過隙，忽然而已。」嘆人生之短暫，可與老聃媲美的，絕無僅有。
參考資料
- Olshansky, S. J. (2016) Measuring our narrow strip of life. Nature, 538(7624), 175-176.
Ageing
Measuring our narrow strip of life
In line with previous research, a demographic analysis corroborates the presence of a limit to human lifespan, indicating that increases in life expectancy are likely to slow down or stop over the coming years.
The British author Annie Besant once wrote1: “out of the darkness of the womb, into the darkness of the grave, man passes across his narrow strip of life.” The ration of time allocated to humans is of profound personal and scientific interest. On page 257, Dong et al.2 turn to the demographic literature to analyse whether there is a limit to human lifespan — and find evidence to suggest that there is.
Before discussing the study at hand, we should define some relevant terms. Lifespan describes how long an individual lives. Life expectancy is a population-based estimate of expected duration of life for individuals at any age, based on a statistical 'life table'. And maximum lifespan is the age reached by the longest-lived member of a species.
Human life expectancy has risen fairly steadily and rapidly over the past 150 years3 in most countries. In 1990, colleagues and I predicted that this increase would slow over time4, and this has proved to be the case5. Maximum lifespan also seems to have risen steadily6, but this too might have reached an upper asymptote — no one is known to have lived longer than Jeanne Calment, who died in 1997 at the age of 122. Thus, the debate about life's limits is ongoing.
Some scientists speculate that fixed limits to life are unlikely to exist, because they cannot be observed using the tools of mathematical demography7. Others suggest that unknown technological advances in the future will continue to drive down death rates8, leading to accelerated gains in life expectancy and maximum lifespan. And yet others argue that there is a limit to lifespan9.
Dong and colleagues used demographic data to investigate whether there is a limit to human lifespan and, by implication, life expectancy. They first hypothesized that, if a biological limit does not exist (or is currently unobservable), the age group experiencing the greatest increase in survival should shift to ever-older groups over time. This hypothesis makes perfect sense, and the authors discovered that, in most countries that have reliable data, the greatest improvement in survival in the oldest age groups peaked in about 1980 and has not shifted since.
Next, the researchers investigated whether increases in maximum lifespan had been observed in recent decades. They discovered that, since the death of Calment, maximum lifespan for humans has regressed. This occurred in spite of the increasing size of ageing populations worldwide, which, in itself, should have led to an increase in maximum lifespan. Dong et al. conclude that these two observations represent compelling evidence that human lifespan has a 'natural limit' (Fig. 1).
Alessandro Grassani/The New York Times/Eyevine
At 116, Emma Morano is the oldest known person alive today. Dong et al.2 provide evidence that we are approaching the natural limit to human lifespan.
Scientists who study ageing know that there is considerable variation in the duration of life across species10, but within species there are fixed attributes associated with life history — and longevity determination is one of them. Under protected living conditions in which predation is largely removed, mice tend to live about 1,000 days10, dogs about 5,000 days10 and humans about 29,000 days11. Clearly, there are biological reasons for each species' average lifespan, so why would anyone think that people could live for much longer than we do now?
The answer lies in the historical context within which human longevity has changed. The 30-year rise in life expectancy at birth seen during the past century has nothing to do with a modified rate of ageing12. Instead, it reflects improvements in public health that have drastically reduced early-age mortality, allowing most people in developed nations to reach old age for the first time in history. Death now clusters in people between the ages of 65 and 95 (ref. 11). But, without further biomedical breakthroughs, life expectancy cannot continue to rise by much, and so future longevity gains will diminish. The crucial question is how much more survival time can be gained through medical technology. With fixed life-history traits, it would seem that we are running up against a formidable barrier.
As the authors rightly point out, the idea of a 'natural limit' to life does not imply that such a limit is a direct by-product of some genetically driven program that causes both ageing and death. Fixed genetic programs that directly cause ageing and death cannot exist as a direct product of evolution, because the end result would be death at an age beyond which almost every member of a species would ordinarily live. A genetic time bomb designed to kill us at older ages is equivalent to automobile manufacturers building in an explosive device that is set off only when a car reaches one million miles. Because most cars are never driven that far, such a device would be useless.
How is it possible to have a biological limit to life, yet no genetic program that runs it? There are biological clocks that measure time from conception and birth, but these metronomes are there to transform a fertilized egg into an adult capable of reproducing. These fixed genetic programs for growth, development, maturation and reproduction (collectively known as a life-history strategy) are products of more than 3.7 billion years of evolution. Biological metronomes do not measure the time to age or die; instead, ageing is an inadvertent by-product of these clocks, which are designed to sustain life.
This distinction is important — it means that there is no fixed limit beyond which humans cannot live, but that there are, nevertheless, limits on the duration of life that are imposed by other genetically determined life-history traits. Think of constraints on running speed as an analogy. No genetic program specifically limits how fast humans can run, but biomechanical constraints on running speed are imposed by a fixed body design that evolved for other purposes. The absence of ageing and death programs opens the door to non-genetic interventions that extend health and length of life, just as new training methods enable us to run incrementally faster. This is precisely why modifying behavioural risk factors such as diet and exercise does extend the period of healthy life, but yields diminishing gains in life expectancy.
Dong and colleagues remind us that humanity is approaching a natural limit to life. This limit is now apparent in national vital statistics. Humanity is working hard to manufacture more survival time, with some degree of success, but we should acknowledge that a genetically determined fixed life-history strategy for our species stands in the way of radical life extension.1
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