Clarification of the Term "Vestigial"

Opponents of evolution always raise the same argument when vestigial traits are cited as evidence for evolution. “The features are not useless,” they say. “They are either useful for something, or we haven’t yet discovered what they’re for.” They claim, in other words, that a trait can’t be vestigial if it still has a function, or a function yet to be found. But this rejoinder misses the point. Evolutionary theory doesn’t say that vestigial characters have no function. A trai...