【英语时差8,16】扭曲的演变途径

 What does "Survival of the Fittest" mean?   Imagine that some predatory animal happens to be born with slightly better vision than average. This improved vision will give it an advantage while hunting, so it'll be more likely to survive and pass on the genes¹ for that good eyesight to future generations. Eventually, the individuals with good eyesight genes will dominate over those without them, and the species as a whole will change, becoming more "fit."This simple example is a pretty good description of how evolution works. Unfortunately, nature is rarely so simple. The same genes can often control more than one physical trait at a time. For instance, what would happen if the "good eyesight" genes in our example also resulted in purple toes? Our hunters would have to evolve this extra trait too, despite the fact that it doesn't necessarily make them any fitter than before.

While purple-toed, keen-eyed hunters are just a made up example, a real animal that demonstrates this is the three-spined stickleback fish of western Canada. These fish moved into glacier-carved lakes thirteen thousand years ago. Over time, they evolved into two separate species. The original is short and thin, and has a small mouth, while the other is long, fat, and wide-mouthed. Why did they evolve this way?

Biologist Dolph Schluter has recently discovered that all three traits--length, thickness, and mouth size--are linked together on the same genes. Although the fittest possible stickleback might be both slender and wide-mouthed, these linked traits make such an evolutionary² jump unlikely.

So evolution doesn't always take the straight road to fitness. It often detours³ along a crooked⁴ path.  

1 genes   

n.基因( gene的名词复数 )

参考例句：

• You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因，所以能够活得很长。 来自《简明英汉词典》
• Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪

2 evolutionary   

adj.进化的；演化的，演变的；[生]进化论的

参考例句：

• Life has its own evolutionary process.生命有其自身的进化过程。
• These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。

3 detours   

绕行的路( detour的名词复数 )； 绕道，兜圈子

参考例句：

• Local wars and bandits often blocked their travel, making countless detours necessary. 内战和盗匪也常阻挡他们前进，迫使他们绕了无数弯路。
• Could it be that all these detours had brought them to Moshi Pass? 难道绕来绕去，绕到磨石口来了吗？ 来自汉英文学 - 骆驼祥子

4 crooked   

adj.弯曲的；不诚实的，狡猾的，不正当的

参考例句：

• He crooked a finger to tell us to go over to him.他弯了弯手指，示意我们到他那儿去。
• You have to drive slowly on these crooked country roads.在这些弯弯曲曲的乡间小路上你得慢慢开车。