Some people see evolution as an undeviating upward march from simple organisms to the very complex,a straight and narrow tree-lined road unswerving across the lowlands.

• 有些人认为进化是从简单生物体到非常复杂的生物体的这么一个不断向上的进程，一条笔直的、狭窄的三车道公路径直穿过低地。