The genome starts piling on mutations that mean nothing; that's how they date the branches of the genome, by looking at the number of neutral mutations.

基因积累了许多无意义的突变,这就是他们如何鉴定基因分支的年代,看中性突变的数量就行了

耶鲁公开课 - 金融市场课程节选

You have n branches on the tree and you count the number of leaves and sum them up.

一共有n根树枝,你数了叶子的数量然后把他们加起来

耶鲁公开课 - 金融市场课程节选