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.

• 紫色的脚趾，敏锐的视力都只是编出来的例子，加拿大西部的三刺鱼为我们展示进化历程，这是一种真正存在的动物。