万物简史 第485期:多灾多难的生命进程(5)

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　　And the more complex they get, the more quickly they appear to go extinct. 它们变得越复杂，好像灭绝得越快。

　　Which is perhaps one reason why so much of life isn't terribly ambitious. 为什么那么多生命没有雄心壮志，这也许是一个原因。

　　So anytime life does something bold it is quite an event, 因此，只要生命干出勇敢的事，都是一件大事。

　　and few occasions were more eventful than when life moved on to the next stage in our narrative³ and came out of the sea. 我们将要讲到，生命向前迈入另一阶段，离开了海洋。这就是极少的大事之一。

　　Land was a formidable environment: hot, dry, bathed in intense ultraviolet radiation, lacking the buoyancy that makes movement in water comparatively effortless. 陆地是个可怕的环境：炎热、干燥，笼罩在强烈的紫外线辐射之中，没有在水中移动的那种相对轻松的浮力。

　　To live on land, creatures had to undergo wholesale⁴ revisions of their anatomies⁵. 在陆地上生活，动物们不得不彻底修正它们的结构。

　　Hold a fish at each end and it sags⁶ in the middle, its backbone⁷ too weak to support it. 要是你用手拿住一条鱼的两端，它的中部就会弯下去，因为它的脊骨不结实，无法支撑自己。

　　To survive out of water, marine⁸ creatures needed to come up with new load-bearing internal architecture—not the sort of adjustment that happens overnight. 为了在离开水以后生存下去，海生动物需要有个新的能够负重的内部架构——这不是一夜之间能调整过来的。

　　Above all and most obviously, any land creature would have to develop a way to take its oxygen directly from the air rather than filter it from water. 尤其重要的，也是最明显的是，任何陆生动物必须学会直接从空气里摄取氧气。而不是从水里过滤氧气。

　　These were not trivial challenges to overcome. 这一些都不是微不足道的困难。都需要克服。

　　On the other hand, there was a powerful incentive⁹ to leave the water: it was getting dangerous down there. 另一方面，动物们对于离开水有着强大的动力：水底下的环境正变得越来越危险。

　　The slow fusion¹⁰ of the continents into a single landmass, Pangaea, 大陆渐渐合并成一个陆块：泛古陆，

　　meant there was much, much less coastline than formerly¹¹ and thus much less coastal¹² habitat. 这意味着海岸线比以前少多了，因而沿海的栖息地也少了。

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