Five rules for the evolution of cooperation

Cooperation is needed for evolution to construct new levels of organization. Genomes, cells, multicellular organisms, social insects, and human society are all based on cooperation. Cooperation means that selfish replicators forgo some of their reproductive potential to help one another. But natural selection implies competition and therefore opposes cooperation unless a specific mechanism is at work. Here I discuss five mechanisms for the evolution of cooperation: kin selection, direct reciprocity, indirect reciprocity, network reciprocity, and group selection. For each mechanism, a simple rule is derived that specifies whether natural selection can lead to cooperation. Evolution is based on a fierce competitionbetween individuals and should thereforereward only selfish behavior. Every gene, every cell, and every organism should be de-signed to promote its own evolutionary success at the expense of its competitors. Yet we ob-serve cooperation on many levels of biolog-ical organization. Genes cooperate in genomes. Chromosomes cooperate in eukaryotic cells. Cells cooperate in multicellular organisms. Ther