Some structures in humans were once thought to have no function, but to have once been useful in some evolutionary ancestor.a They were called vestigial organs. As medical knowledge has increased, at least some function has been discovered for all alleged vestigial organs.b For example, the human appendix was once considered a useless remnant from our evolutionary past. The appendix plays a role in antibody production, protects part of the intestine from infections and tumor growths,c and safely stores “good bacteria” that can replenish the intestines following bouts of diarrhea.d The absence of true vestigial organs implies evolution never happened.