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. […]
Evolution is based on a fierce competition between individuals and should therefore reward 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. There are many examples of cooperation among ani- mals. Humans are the champions of cooperation: From hunter-gatherer societies to nation-states, cooperation is the decisive organizing principle of human society. No other life form on Earth is engaged in the same complex games of cooper- ation and defection. The question of how natural selection can lead to cooperative behavior has fascinated evolutionary biologists for several decades.
Five Rules for the Evolution of Cooperation by Martin A. Nowak