ing to avoid the sterile caste. We have delineated cheating into fixed, facultative, and social parasite forms. We have shown that cheating can be controlled by high relatedness, kin discrimination, pleiotropy, or lotteries. We have shown that conflict can be controlled by conventions and power. The first cells to starve become spore, as do stronger cells. A small, toxic molecule called DIF-1 mediates social interactions. We and others have backed up much of this work with specific genes and knockouts. Further whole-genome outcomes are on the horizon, as is a much more detailed understanding of kin discrimination. Frontiers include the farming symbiosis and exploration of the sexual cycle. Clearly, this is a system that has yielded many important secrets about the cooperative side of major transitions.
We thank John Avise and Francisco Ayala for inviting us to help organize the Arthur M. Sackler Colloquium on Cooperation. We thank many colleagues for helpful discussions of these points, especially Sandie Baldauf, Koos Boomsma, Kevin Foster, Richard Gomer, Ashleigh Griffin, Rob Kay, Richard Kessin, Adam Kuspa, Gene Robinson, Gadi Shaulsky, Chris Thompson, Greg Velicer, and Stuart West as well as our own laboratory group. Our research is supported by the U.S. National Science Foundation under Grants DEB 0816690 and DEB 0918931.