The topic: Sociality and signal evolution
The gist: There’s a trade-off between social recognition (the ability to learn, memorize, and recognize individuals within a group due to repeated interactions) and elaborate, external quality signals (think peacock feathers or lion manes, which don’t require repeated interactions but still can communicate important info about the individual giving the signal). Social group size may drive selection to favor either social recognition (in smaller groups, in which repeated interactions with individuals are common) or external quality signals (in larger groups, in which interactions with randos are common).
One question that remains is how social network size within a larger social group can affect signal evolution. If social networks within a larger social group are relatively small, can selection on signals parallel that within small social groups? Or is it the quantity of interactions (with either unknown or known members or both) in larger groups that primarily drive signal evolution type?
Why care? This research can give us a predictive framework to understand species’ use of signals (be they visual, auditory, or chemical) given what their social structure looks like and vice versa. Also, the framework can have far-reaching implications for understanding social behavior within most animals, including us humans. Because of the inherent trade-off between the two, social recognition may limit the evolution of quality signals, which may explain why we don’t see quality signals in humans (at least non-cultural ones).
The bottom line: Understanding signal use is important for understanding social behavior because it gives us an idea of how individuals interact with one another in a social group and how information about potential rivals, allies, or mates is gathered and used.