Nearly everyone has heard stories of how humans with one damaged sense (e.g. hearing or sight) often experience heightened sensitivity in other areas. Now, a new study suggests that the theory of sensory trade-offs may hold true for the evolution of species as well. For instance, primates (including humans) have a highly developed visual sense, but the ability to see all the colors of the rainbow may have come at the expense of, say, a superior sense of smell.