The presence of gill slits in embryos of all vertebrates supports which theory?

The presence of gill slits in the embryos of all vertebrates supports the theory of recapitulation. This theory, often summarized by the phrase "ontogeny recapitulates phylogeny," proposes that the development of an organism (ontogeny) reflects the evolutionary history of that organism's species (phylogeny).

In less complex terms, as the embryos of vertebrates develop, they exhibit features reminiscent of their evolutionary ancestors. The gill slits observed in the early stages of development are indicative of a common ancestry among vertebrates. These structures are reminiscent of the gills found in fish, supporting the idea that all vertebrates share a common origin and that their embryonic development retraces their evolutionary lineage.

By highlighting the similarities in embryonic development across diverse vertebrate species, the theory of recapitulation reinforces the concept of evolutionary relationships and common descent. This observation encourages the understanding of how complex organisms develop and hints at their ancestral characteristics, which are reflected during early stages of growth.