vestigial structures

基本解释

This is why these vestigial structures are almost always removed when they begin to come in.
所以今天我们总是在它们刚刚开始长的时候就会拔掉。
Similar in concept to vestigial structures are atavisms, which are the reappearance of a structure or trait that isn’t found in the immediate ancestors.
跟退化结构相似的概念还有返祖现象，它的意思是生物体身上重新出现直系祖先没有的结构或特征。
But these vestigial organs and structures, once useful in an ancestor and now diminished in size, complexity, and/or utility, carry important information and give us clues to our evolutionary past.
可是事实上，这些退化的器官和结构在它们的祖先身上是有用的，而现在则从尺寸、结构复杂性和实用性上面都逐渐退化，这提示了我们关于人类进化的重要线索。