The sensory-bias model, as Coyne outlines on pages 166-167, suggests that sexual dimorphisms evolved as a result of biases in the female nervous system – whether it be like the theoretical example that he shared with the mutant male's red coloration on his breast stimulating the female's visual preference for red color, or simply, a stimulation of the nervous system as a result of more extravagant displays. Consider why these preferences are so nonspecific; why might it be 'better' to recognize the red coloration rather than a certain chemical secretion? And to what extent do these animals have to recognize and 'appreciate' different behaviors or physical adaptations (such as shiny fur or long mating calls)? Why might females have adaptations to be able to process these different adaptations on males? Why spend more energy, for instance, developing eye spots to visually choose males if that's their only purpose? Is it worth it?