I recently watched a documentary about the evolution of eyes. Beginning with simple photoreceptive cells in jellyfish-like creatures, the organ eventually developed into compound and camera-style eyes, according to the documentary. I found it really interesting, but it got me wondering: How exactly does a creature’s brain (or general nervous system) derive advantage from the new sensory organ?
For example, if a jellyfish suddenly develops simple eyes, its nervous system receives a signal from the photoreceptive cells. How would the nervous system, not adapted to receiving this information, be able to make use of the new input? What if the initial response to the new signal actually caused the creature to behave detrimentally – wouldn’t that cause the presence of the organ to be selected against?
tl;dr: How would improvements in eye “hardware” be selected for if the “software” is not yet adapted to make effective use of it?