#game-theory #biology >The greatest opportunity for selfish genes comes during sex. Most animals and plants are diploid: Their genes come in pairs. But diploidy is an uneasy partnership between two sets of genes, and when partnerships end, things often get acrimonious. The partnerships end with sex. During [[Biology/Evolution/Meiosis|meiosis]], the central genetic procedure of sex, the paired genes are separated to make haploid sperm and eggs. Suddenly each gene has an opportunity to be self ish at its partner's expense. If it can monopolize the eggs or sperm, it thrives and its partner does not. ~ [[Biology/Matt Ridley|Ridley]] Some self ish genes have seized this opportunity and have become selfish, at least in the sense that they have produced selfish effects. Most selfish genes are not selfish in the sense that they are conscious or have intentions. They are selfish only because they act in ways that make them more abundant. Their selfishness is a product of their structure. The selfishness of genes leads to conflict among genes within organisms and to conflict among organisms themselves. The conflict among genes is the central subject of Richard Dawkins's 1976 book, The Selfish Gene, the book that gave the selfish gene its name. The conflict among organisms is the central subject of Robert Trivers's 1972 book, The Evolution of Reciprocal Altruism. The conflict between genes and organisms is the central subject of W. D. Hamilton's 1964 paper, "The Genetical Evolution of Social Behaviour." The selfish gene was originally a metaphor. It was a way of thinking of genes as agents, with their own goals and ambitions, that try to maximize their growth by controlling the bodies that carry them. But the metaphor turned out to be useful. It allowed biologists to think about biology in new ways, and to understand many old puzzles in new ways. The selfish gene is now more than a metaphor. It is a theory. It is an attempt to explain a great many evolutionary facts. The selfish gene theory has been tested against observations, and some of its predictions have been confirmed. The selfish gene theory has also been attacked. It has been criticized, criticized, and criticized. Some of the criticisms have been shown to be wrong. Others have led to modifications of the theory. The selfish gene theory is not the only theory about evolution. It competes with many other theories. But the selfish gene theory is the best theory we have. It is the theory that makes the most sense of the evidence. The selfish gene theory has two parts. The first is what I will call the replicator hypothesis. The second is what I will call the vehicle hypothesis. The replicator hypothesis explains how replicators—the things that propagate themselves—make copies of themselves. The vehicle hypothesis explains how replicators control the bodies that carry them. The Replicator Hypothesis The replicator hypothesis begins with a simple idea. Replicators are things that make copies of themselves. They are things that reproduce themselves. Genes are replicators. So are viruses and computer programs. How do replicators reproduce themselves? Similar topic links: [[Genetic cooperation]] [[Selfish gene]] [[Pros and cons of cloning yourself]] [[Evolution]] [[Genome]]