“退化的”用英语怎么说？

人类仍有尾巴退化的痕迹.A human being has the vestige of a tail.杂质和污染对退化的作用不能忽视.The role of dopants and contaminants in degradation cannot be ignored.虚圆点实际上是一退化的二次曲线.The circular points are really a degenerate conic....