Everyone has had the experience of standing in a long line waiting to get something when another person rudely butts in front to avoid the long wait. If you’re the one at the end of the line, you’ll probably be pretty unhappy at the behavior, but if you’re a scientist, you may wonder about the molecular basis of such anti-social action. Is it learned or is it encoded in the genome? We’re a long ways away from settling this nature/nurture argument, but an interesting set of first steps has been taken to identify social genes in one of the simplest eukaryotic organisms – Dictyostelium discoideum. In a publication in the journal Nature, researchers at Rice University and the Baylor College of Medicine reported the identification of 100+ genes that cause the organism to “play nice.” Cooperation between cells is important in unicellular organisms for processes as diverse as tooth decay, medical implant-related infections, and much more. To identify Dictyostelium genes for social behavior, scientists screened 10,000 randomly mutated strains of the organism and checked for individuals that “cheated,” the cellular equivalent of butting in line. Cheating allows mutated individuals to have advantages over their non-cheating siblings and enables researchers to easily flag the gene(s) involved. Why don’t all cells cheat then? The answer likely lies in the evolutionary advantage to the organism of social behavior. Strains that cheat probably won’t survive as long as ones that cooperate. Perhaps humans should take note.