How Does Comparative Embryology Support the Theory of Evolution?

Comparative embryology supports the theory of evolution because scientists have found that the embryos of many different species show similarities, which implies they share a common origin. For example, in humans the embryo passes through a stage in which it has a gill structure similar to that of fish. Human embryos also have a tail, much like other primates, though the tail is usually re-absorbed before birth, and this suggests that, even though their adult forms are different, these various species all have a common ancestor.