TEMPE, Ariz. How social or altruistic behavior evolved has been a central and hotly debated question, particularly by those researchers engaged in the study of social insect societies ants, bees and wasps. In these groups, this question of what drives altruism also becomes critical to further understanding of how ancestral or primitive social organizations (with hierarchies and dominance fights, and poorly developed division of labor) evolve to become the more highly sophisticated networks found in some eusocial insect collectives termed superorganisms.
In a paper published online May 21 before print by the Proceedings of the National Academy of Sciences (PNAS), a pair of researchers from Cornell University and Arizona State University propose a model, based on tug-of-war theory, that may explain the selection pressures that mark the evolutionary transition from primitive society to superorganism and which may bring some order to the conflicted thinking about the roles of individual, kin, and group selection that underlie the formation of such advanced eusocial groups.
A superorganism ultimately emerges as a result of intergroup competition according to findings by theoretician H. Kern Reeve of Cornell Universitys Department of Neurobiology and Behavior and professor Bert Hlldobler of Arizona State Universitys School of Life Sciences and Center for Social Dynamics and Complexity.
Reeve and Hlldoblers model is unique in that it is comprised of two interlocked nested tug-of-war theories. The first piece describes the tug of war over resource shares within a group or colony (intragroup competition), and the second piece incorporates the effects of a tug-of-war between competing colonies (intergroup competition).
According to Hlldobler, the path to colonial supergiant is first paved by the maximization of the inclusive fitness of each individual of the society. How this might arise, he believes, is that competition that might
Contact: Margaret Coulombe
Arizona State University