評論
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The Earth. on the other hand, was born only 4.6 billion years ago. That result comes from measurements of the ages of meteorites and from the ages of the moon rocks brought back by the Apollo astronauts. Since meteorites and the moon are relatively unchanged samples of solar-system material, dating back to the birth of the planets, their age is thought to give a good estimate of the age of the Earth.
而地球僅誕生于46億年前。這個結(jié)論是通過檢測隕星的年齡和阿波羅號宇航員帶回的月球巖石的年齡得出的。由于隕星和月球是行星誕生的時候太陽系物質(zhì)的相對說來未發(fā)生變化的樣本，所以人們認為，它們的年齡為估計地球的年齡提供了很好的參照。
Thus, many planets circling distant stars are 5, 10 and even 15 billion years older than the Earth.It follows that the Earth is a very recent arrival in the cosmic family of planets, and man is among the youngest denizens of the Universe.
這樣算來，許多圍繞遙遠的恒星運轉(zhuǎn)的行星要比地球古老50億、100億年乃至150億年。由此可見，地球是宇宙行星系中一個相當晚的后來者，而人類則是宇宙中最年輕的居民之一。
Of course, the fact that life elsewhere is older than man does not necessarily mean that this life is more intelligent. However, other scientific evidence suggests that this is likely to be the case. Throughout the last 300 million years of life on Earth, only one seemingly universal trend can be discerned in evolution; this is the trend toward greater intelligence. Since before the fishes left the water, the most intelligent form of life present on Earth in each era has been the rootstock out of which new and still more intelligent forms have evolved. The line of increasing intelligence stretches unbroken from the fishes to the reptiles to the mammals, the primates and man. Apparently, intelligence -- which permits a flexible response to changing conditions -- has a greater survival value than any other single trait.
當然，別處的生命比人類年長的事實并不一定意味著那些生命具有更高的智慧。然而，其他科學證據(jù)表明，情況可能確實如此。從地球上的生命經(jīng)歷的最近3億年間，僅能看出一個像似普遍的進化規(guī)律，這就是向更高智慧發(fā)展的趨勢。早自魚類離開水之前開始，地球上每個時期出現(xiàn)的智能最高的生命形式，總是演化新的具有更高智慧的生命形式的來源。智慧不斷提高像一條線從未間斷過，它從魚類延伸到爬行動物，再延伸到哺乳動物、靈長目動物和人類。顯然，智慧——它使對不斷變化的環(huán)境作出靈活反應成為可能——與其他任何單個特征相比，對于生存具有更高的價值。
