Lesson 37 The process of ageing 衰老过程
At the age of twelve years, the human body is at its most vigorous. It has yet to reach its full size and strength, and its owner his or her full intelligence; but at this age the likelihood of death is least. Earlier, we were infants and young children, and consequently more vulnerable; later, we shall undergo a progressive loss of our vigour and resistance which, though imperceptible at first, will finally become so steep that we can live no longer, however well we look after ourselves, and however well society, and our doctors, look after us. This decline in vigour with the passing of time is called ageing. It is one of the most unpleasant discoveries which we all make that we must decline in this way, that if we escape wars, accidents and disease we shall eventually ‘die of old age’, and that this happens at a rate which differs little from person to person, so that there are heavy odds in favour of our dying between the ages of sixty-five and eighty. Some of us will die sooner, a few will live longer — on into a ninth or tenth decade. But the chances are against it, and there is a virtual limit on how long we can hope to remain alive, however lucky and robust we are.
Normal people tend to forget this process unless and until they are reminded of it. We are so familiar with the fact that man ages, that people have for years assumed that the process of losing vigour with time, of becoming more likely to die the older we get, was something self-evident, like the cooling of a hot kettle or the wearing-out of a pair of shoes. They have also assumed that all animals, and probably other organisms such as trees, or even the universe itself, must in the nature of things ‘wear out’. Most animals we commonly observe do in fact age as we do, if given the chance to live long enough; and mechanical systems like a wound watch, or the sun, do in fact run out of energy in accordance with the second law of thermodynamics (whether the whole universe does so is a moot point at present). But these are not analogous to what happens when man ages. A run-down watch is still a watch and can be rewound. An old watch, by contrast, becomes so worn and unreliable that it eventually is not worth mending. But a watch could never repair itself — it does not consist of living parts, only of metal, which wears away by friction. We could, at one time, repair ourselves –well enough, at least, to overcome all but the most instantly fatal illnesses and accidents. Between twelve and eighty years we gradually lose this power; an illness which at twelve would knock us over, at eighty can knock us out, and another 700 for the survivors to be reduced by half again.
人体在12岁时是生命力最旺盛的时期。虽然这个时期人的身材、体力和智力还有待发展和完善，但在这个年龄死亡的可能性最小。再早一些，我们是幼儿和小孩子，身体较脆弱；再迟一些，我们就要经历生命力和抵抗力逐步衰退的过程。虽然这个过程起初难以觉察，但最终会急转直下，不管我们怎样精心照料我们自己，不管社会和医生怎样对我们进行精心照顾，我们也无法再活下去了。生命力随着时间的流失而衰退叫做衰老。人类发现的最不愉快的一个事实是：人必然会衰老。既使我们能避开战争、意外的事故和各种疾病，我们最终也会“老死”；衰老的速度在人与人之间相差甚微，我们最可能死亡的年龄在65至80岁之间，有些人会死得早一些，少数人寿命会长一些 — 活到八十几岁或九十几岁，但这种可能性很小。不管我们多么幸运，多么健壮，我们所希望的长寿实际上是有限度的。