But the whole point of evolutionary theory is that there is no predetermined "direction" to natural selection! There is no "higher" or "upward" in evol theory; there is simply the emergence of traits that help a species to survive under specific environmental conditions. --Thus the disappearance of vision in some crustacean species that live in the dark. The lobsters without eye stalks are not "higher" or "lower" on some evolutionary ladder than lobsters with eye stalks; rather, they are well adapted to the environment is which they live.
--Now, I agree that the popular representation of evolution encourages the "great chain of being" fallacy, but that is a misunderstanding of the basic premises of evolutionary theory. In fact, evolutionary theory and research demonstrate how silly that idea is. For instance, in evolutionary terms (survival and reproductive success), insects are kicking primates' asses. From the perspective of evolutionary theory, it is incoherent to argue that primates (or homo homo sapiens) are somehow "higher" on a unidimensional evolutionary ladder than insects are.
Miles