Scents of self: The expression component of self/non-self recognition systems

Tsutsui, N. D. 2004. Scents of self: The expression component of self/non-self recognition systems. Annales Zoologici Fennici, 41: 713-27.

 The ability to distinguish self from non-self is one of the fundamental organizing
principles of life on Earth. Such recognition systems permit the unification of dis-
tinct elements into cohesive social groups, from multicellular organisms to colonial
“superorganisms”. Although the phenomenon of self/non-self recognition has been
studied extensively, recent advances have provided fascinating glimpses into the inner
workings of recognition systems, and have illuminated some of the extreme forms of
selection that drive the evolution of label polymorphism. This polymorphism permits
different classes of individuals to be distinguished with high precision, thus creating
barriers to outsiders who seek entry into the social group. Here I review the structure
and evolution of self/non-self recognition systems across a variety of taxa, with par-
ticular attention to the selective forces that maintain label polymorphism. I highlight
recent findings that have opened up new avenues of research, and suggest future direc-
tions that may provide additional novel insights.