How does signal selection work? Any ability we have to determine the actual capabilities of others will be used for that end. And any means we have for manipulating the behavior of others will tend to be used for that end, if possible. In humans, our sensory abilities limit the kinds of information we can collect about other humans and animals, and therefore our ability to learn about them and predict their behavior is limited to what our senses tell us. However, many other animals are not so restricted in what they can learn about other organisms; they have other avenues for reading each other's minds as well as manipulating each other's behavior. I thought about these other sensory abilities after watching “The Cove” the other day.
Dogs live in a world filled with scents. Their noses are so sensitive that they can smell the change in body odor associated with the growth of cancer cells. Of course, dogs do use chemical signals to manipulate the behavior of other dogs and determine their intentions, we just don't yet know the extent of their use of this signalling ability. Another interesting example is that of dolphins. Their sonar abilities are more advanced than anything man has yet created. They are capable of seeing through a person and revealing details of internal structures such as the heart and skeletal system. Could it be that dolphins use this information to learn about animals and other dolphins too? And if they can use the information, could certain features of it be subject to signal selection? I say yes. I know of no features in the natural living world that are beyond the reach of signal selection. Perhaps female dolphins can determine which males have strong healthy hearts or other organs and preferentially mate with these males over others. Or perhaps status in pods of whales is partially determined by skeletal features. We just don't know. Of course, it would be easier for dolphins to determine another's health through more obvious behavioral means. But I hope the point I am making is clear. Whereas chemical signalling in dogs and other animals is better studied, the use of sonar information and signalling is poorly understood. When we understand what kind of signals animals can sense in the world around them, and how they send and receive these signals, our view into the minds of other animals like dogs and dolphins will be clearer, assuming we have not degraded the environment to such a point that the minds of cetaceans would no longer be available to study. In the event this happens, our children, biological or artificial, will condemn us for consuming our evolutionary cousins. Hopefully we will be spared the same treatment.