广播电视英语短句 第 84 课：有关智齿-4

And removal is called for in cases where fluid collects around a wisdom tooth that is partly or fully below the gum. 再者，当部分萌出或者完全未萌出的智齿周围有液体积聚时，也应该拔除。

But why do we have wisdom teeth if we often need to get them removed? 但是，既然通常情况下都要拔除智齿，它们为什么会存在呢？

One theory has to do with our diets. 有一个理论认为与我们的饮食有关。

Scientists say the diet of prehistoric humans probably required more chewing teeth. 科学家们说，史前人类的饮食结构可能要求他们有更多的咀嚼齿。

Life was probably a little rougher on the teeth back then, too. So it was good to have extras. 对于位于后部的牙齿来说，生活可能有点艰辛。因此，如果有多余的牙齿就更好了。