Dawkins likes to think of the genes as getting together to build a survival machine, i.e. the animal body, which acts as their vehicle and protection. A good metaphor for this would be the way humans get together to build a fortified city to enable them to ward off attacks and generally survive against the elements. The city needs walls to defend its citizens and it needs weapons to ward off attack. The body is the gene’s moat, high wall, cannon, etc. And just as no gene could construct such a thing alone, requiring the cooperation of many genes, though each is inherently selfish, so no individual human being could build the right sort of fortified city, and so needs to cooperate with other selfish individuals. The genes make a social contract and then proceed together to defend and arm themselves. Thus “The Citizen Gene”.