Dawkins uses the metaphor of a fictional alien race called “Andromedans” to explain how genes control the bodies of organisms. Andromedans are aliens who want to control planet earth. Unfortunately, they live very far away from earth. So far, in fact, that if they send a message to earth, they would be long dead before a response comes back. Instead of a message, they decide to send instructions for building a computer. When those instructions finally reach earth, humans decode them and build the computer, which controls earth. In the metaphor, the computer stands for an organism’s brain. Genes control organisms in the same sense that the Andromedans can be thought of as controlling earth. Similarly, genes don’t control organisms directly, the way that a puppeteer controls a puppet. Instead, genes act by containing instructions for building brains, and these brains then govern the organisms’ behavior in a way that is beneficial to the genes.
In this metaphor, both the Andromedans and the instructions they send out are analogous to genes. This point matters to Dawkins because he wants to argue that genes (and not organisms or species) evolve. In order to make his view convincing, he needs a plausible account of why brains exist, since we normally take brains, and not genes, as the powerhouses of our agency.
Andromedans Quotes in The Selfish Gene
Just as the Andromedans had to have a computer on earth to take day-to-day decisions for them, our genes have to build a brain.