"The basic principles of evolutionary biology would seem to dictate that any natural phenomenon as prominent in our lives as our experience of consciousness must necessarily have some discernible and quantifiable effect in order for it to exist, and to persist, in nature at all. It must, in other words, confer some selective advantage. And that raises an obvious question: What possible selective advantage could consciousness offer if it is only a functionless phantasm? How could consciousness ever have evolved in the first place if, in and of itself, it does nothing? Why, in short, did nature bother to produce beings capable of self-awareness and subjective inner experience? True, evolutionary biologists can trot out many examples of traits that have been carried along on the river of evolution although not specifically selected for (the evolutionary biologists Stephen Jay Gould and Richard Lewontin called such traits spandrels, the architectural term for the elements between the exterior curve of an arch and the right angle of the walls around it, which were not intentionally built but were instead formed by two architectural traits that were "selected for"). But consciousness seems like an awfully prominent trait not to have been the target of some selection pressure. As James put it, "The conclusion that [consciousness] is useful is...quite justifiable. But if it is useful, it must be so through its causal efficaciousness."