One possible explaination (I heard of. Not sure how mainstream an explanation is) is that insect metamorphosis is the result of two species fusing together in a

One possible explaination (I heard of. Not sure how mainstream an explanation is) is that insect metamorphosis is the result of two species fusing together in a kind of chimera. One "piggybacking" on the other and gradually each phase specializing EDIT: An article that contains some more pointers (research papers etc) on the idea: https://www.npr.org/sections/krulwich/2012/08/01/157718428/are-butterflies-two-different-animals-in-one-the-death-and-resurrection-theory https://www.npr.org/sections/krulwich/2012/08/01/157718428/a...