After our ancestors began to see color, a gene important in the pheromone-signaling pathway suffered a deleterious mutation, making it impossible for the scent signals to reach the brain, Zhang said.

张教授表示，在我们的祖先开始看到颜色后，一种对信息素信号通路十分重要的基因遭受了有害变异，使气味信号不能到达大脑。

youdao

First, when a new copy of copia inserts itself into a fly's genetic material, it may cause a deleterious mutation to a previously healthy gene (hence all the copia-related mutations detected by geneticists).

ECONOMIST: Truly selfish genes