Interaction is the basis for all human social behavior. Without interactions, there would be no society, no group dynamics, no fun and festivities, and certainly no culture and civilization; we would each scurry from birth to death in a sad, solitary existence. But if anything, interactions are even more important in the physical world, for without interactions, the universe as we know it simply would not exist. There would be no galaxies, no stars, no planets, and therefore no life; there would not even be stable atoms without the various types of interactions to bind all the subatomic particles together. Something that fundamental in both the physical and the social universes can hardly be without deep parallels. So there are, and in this case, it turns out that while much can be learned about human interactions from their analogs in the natural world, even more can be learned about interactions in nature from the way people interact.