You know that little pink thing nestled in the corner of your eye? It’s actually the remnant of a third eyelid. In humans, it’s vestigial, meaning it no longer serves its original purpose. There are several other vestigial structures in the human body, quietly riding along from one of our ancestor species to the next. But why have they stuck around for so long?

你知道那个依偎在你眼角的粉红色小东西吗？它实际上是第三只眼睑的残余物。在人类中，它是残存的，这意味着它不再为其最初的目的服务。人体中还有其他一些遗留结构，悄悄地从我们的一个祖先物种延续到下一个物种。但是，为什么它们坚持了这么久？