It is good to look like you
It is an individual difference so obvious to us that we never think about it. People look different from each other. I'm not talking about fluctuating asymmetry or melanin content or facial attractiveness, but rather your overall physiognomy. Perhaps there is some advantage to being identifiable to other individuals:
Identifying broad-scale evolutionary processes that maintain phenotypic polymorphisms has been a major goal of modern evolutionary biology…Traits used for individual recognition are strikingly variable and have evolved independently in numerous lineages…Theoretical models suggest that individuals may benefit by advertising their identities with distinctive, recognizable phenotypes. Here, we test the benefits of advertising one's identity with a distinctive phenotype. We manipulated the appearance of Polistes fuscatus paper wasp groups so that three individuals had the same appearance and one individual had a unique, easily recognizable appearance. We found that individuals with distinctive appearances received less aggression than individuals with nondistinctive appearances. Therefore, individuals benefit by advertising their identity with a unique phenotype…Given that recognition is important for many social interactions, selection for distinctive identity signals may be an underappreciated and widespread mechanism underlying the evolution of phenotypic polymorphisms in social taxa.
Sheehan and Tibbetts. Evolution of identity signals: frequency-dependent benefits of distinctive phenotypes used for individual recognition. Evolution (online in advance of print) doi:10.1111/j.1558-5646.2009.00833.x
