Vestigial structures take many forms: organs, behaviors, and even biochemical processes. Their defining characteristic is they are structures that a species has retained, but no longer serve their ...

As with many body organs, the human central nervous system contains many structures and cavities that may have had functions in embryonic and fetal life but are vestigial or atrophic at maturity.

Organisms may retain nonfunctional anatomical features as a consequence of evolutionary natural selection. Resultant atavistic and vestigial anatomical structures have long been a source of perplexity ...