MOLECULAR VESTIGES. “Just as illnesses, injuries, and other accidents of ontogeny often leave remains in the form of scars where tissues have incompletely healed from damage, chance events of phylogeny can likewise leave ‘vestiges’ in the form of molecules and nucleic acid sequences that are non-functional (as might apply to ‘junk DNA’).”
https://evolution-outreach.springeropen.com/articles/10.1186/s12052-014-0012-5