The enigma of vestigial tissues.

There are several structures and various tissues in the human body that appear to be functionless relics of ancestral or embryonic development. As such they have long been of interest and have been cited in support of theories of evolution and of oncogenesis. Evidence can be adduced to show that these remnants are not necessarily degenerate, nor are they inevitably functionless. Vestigial tissues are especially common in tooth-bearing areas of the mouth, and the span of tooth development from early embryonic life until adolescence affords unique opportunities for studying the part played by embryonic remnants in later life.