The Selfish Gene is a 1976 popular science book by Richard Dawkins that espouses the gene-centred view of evolution. It builds upon the thesis of George Christopher Williams's Adaptation and Natural Selection (1966) and W. D. Hamilton's work on kin selection. From the gene-centred view, it follows that the more genes two individuals share, the more sense it makes for them to co-operate.
The book introduced the term meme for a unit of cultural evolution analogous to the gene. Memetics has become a subject in its own right in the years since. In popularising Hamilton's ideas, as well as making its own valuable contributions to the field, the book has also stimulated research on human inclusive fitness.
The "selfish gene" is a metaphor for the gene-centred view of evolution. As such, the book is not about a particular gene that causes selfish behaviour; in fact, much of it is devoted to explaining the evolution of altruism. Dawkins says of the title that he "can readily see that it might give an inadequate impression of its contents" and in retrospect wishes he had taken Tom Maschler's advice and titled it The Immortal Gene. He laments that “Too many people read it by title only.” In response, he expanded on the evolution of altruism in the BBC documentary Nice Guys Finish First.
Background Dawkins builds upon George Christopher Williams's book Adaptation and Natural Selection (1966), which argued that altruism is not based upon group benefit per se, but results from selection that occurs "at the level of the gene mediated by the phenotype" and that any selection at the group level occurred only under rare circumstances. W. D. Hamilton and others developed this approach further during the 1960s; they opposed the concepts of group selection and of selection aimed directly at benefit to the individual organism: Despite the principle of 'survival of the fittest' the ultimate criterion which determines whether [a gene] G will spread is not whether the behavior is to the benefit of the behaver, but whether it is to the benefit of the gene G ...With altruism this will happen only if the affected individual is a relative of the altruist, therefore having an increased chance of carrying the gene. — W. D. Hamilton, The Evolution of Altruistic Behavior (1963)
The book's central metaphor is a means of explicating the gene-centred view of evolution.
Book Title Dawkins recalls showing The Selfish Gene to Tom Maschler, who "liked the book but not the title". He suggested The Immortal Gene. Dawkins writes that "Maschler may have been right. Many critics, especially vociferous ones learned in philosophy as I have discovered, prefer to read a book by title only. No doubt this works well enough for The Tale of Benjamin Bunny or The Decline and Fall of the Roman Empire, but I can readily see that ‘The Selfish Gene’ on its own, without the large footnote of the book itself, might give an inadequate impression of its contents."
Contents 1. Why Are People? Dawkins writes that "Intelligent life on a planet comes of age when it first works out the reason for its own existence. ... Living organisms had existed on earth, without ever knowing why, for over three thousand million years before the truth finally dawned on one of them. His name was Charles Darwin." Darwin (and Alfred Russel Wallace, working independently) discovered the mechanism of evolution: natural selection.
2. The Replicators Dawkins introduces the term replicator to describe self-replicating molecules like DNA and RNA. He considers the origin of life with the emergence of replicators. The original replicator was the first molecule which managed to reproduce itself and thus gained an advantage over other molecules within the primordial soup. As replicating molecules became more complex, Dawkins postulates, they evolved cells serving as survival machines. Cells joined to form bodies.
3. Immortal Coils Dawkins expands on DNA, its helical structure and its organisation into chromosomes. Genes are DNA segments which are translated into proteins. Darwin’s coeval Gregor Mendel worked out the laws of inheritance and found that traits are inherited as discrete units. In meiosis, the production of gametes, genes are recombined during crossing over. The individual organism is analogized to a boat of rowers that must each work together to travel. The average performance of each gene, in the environment formed by the other genes, determines how prevalent it will be in the next generations. Dawkins mentions Medawar's selection shadow theory of aging, which states that the selection pressure declines as an organism ages past reproductive maturity, for a gene that's lethal earlier in life prevents all future chance of reproduction, while a gene lethal in old age will affect the number of offspring less. Dawkins also raises the question of how sex and chromosomal crossover evolved, suggesting that the fact that only half of the genes of an individual are passed down through sexual reproduction poses less of a problem when one considers the genes for sexuality or crossover as selfishly manipulating the other genes for its own ends.
4. The Gene Machine Dawkins discusses the evolution of behaviour. Genes encoding behaviours that cause those genes to be passed on will naturally be selected for. He provides various examples.
5. Aggression Dawkins discusses John Maynard Smith’s evolutionarily stable strategy, "a strategy which, if most members of a population adopt it, cannot be bettered by an alternative strategy … once an ESS is achieved it will stay: selection will penalize any deviation from it." He gives the example of the hawk-dove game, where aggressive 'hawks' and non-aggressive 'doves' (which pretend to be aggressive) compete for some resource, with the hawks suffering severe losses against other hawks while gaining advantage against doves, and with doves suffering small losses against other doves (due to time wasted posturing until one eventually backs down). Even though both hawk and dove are Nash equilibria neither are evolutionarily stable, with the evolutionarily stable strategy being an intermediate ratio of 'hawks' (aggressors) and 'doves' (nonaggressors). This illustrates how evolution does not work for the 'good of the species', as the species on average would benefit more if every member was dove (and benefit the most on average at a different ratio with less hawks). In the presence of some uncorrelated asymmetry, like which member is the intruder or the defender of territory, the mixed ratio is no longer an evolutionarily stable strategy - instead the stable strategy is to play hawk when defending and dove when intruding or vice versa. In real life, there is usually some advantage to defending, which makes that become the equilibria present. Furthermore, if intruders played hawk and defenders played dove, then there would be an incentive to try to be the intruder and thus to move around all the time, wasting resources. Dawkins, however, provides an example of a spider species that in fact flees when another intrudes, leading to a chain of evictions.
6. Genesmanship Dawkins discusses kin selection: "Close relatives – kin – have a greater than average chance of sharing genes. It has long been clear that this must be why altruism by parents toward their young is so common. What R. A. Fisher, J. B. S. Haldane and especially W. D. Hamilton realized was that the same applies to other close relations—brothers and sisters, nephews and nieces, close cousins. If an individual dies in order to save ten close relatives, one copy of the kin-altruism gene may be lost, but a larger number of copies of the gene is saved."
7. Family Planning Dawkins discusses David Lack’s principle. Natural selection, according to Lack, adjusts initial clutch size so as to take maximum advantage of these limited resources.
8. Battle of the Generations Dawkins discusses R. L. Trivers’s concept of parental investment, "any investment by the parent in an individual offspring that increases the offspring’s chance of surviving (and hence reproductive success) at the cost of the parent’s ability to invest in other offspring".
9. Battle of the Sexes Dawkins discusses Darwin’s theory of sexual selection. Females can afford to be choosy in their mates, and select for attractive traits in males. Fisher's principle explains why a 50:50 ratio of males to females is evolutionarily stable. This is true even in an extreme case like the harem-keeping elephant seal, where 4% of the males get 88% of copulations. In that case, the strategy of having a female offspring is safe, as she will have a pup, but the strategy of having a male can bring a large return (dozens of pups), even though many males live out their lives as bachelors.
10. You Scratch My back, I’ll Ride on Yours Dawkins discusses reciprocal altruism. Amotz Zahavi's theory of honest signalling explains stotting as a selfish act that improves the springbok's chances of escaping from a predator by indicating how difficult the chase would be. Dawkins discusses why many species live in groups, achieving mutual benefits through mechanisms such as Hamilton's selfish herd model: each individual behaves selfishly but the result is herd behaviour. Altruism can evolve, as in the social insects such as ants and bees, where workers give up the right to reproduce in favour of a sister, the queen; in their case, the unusual (haplodiploid) system of sex determination may have helped to bring this about, as females in a nest are exceptionally closely related.
11. Memes Dawkins discusses cultural evolution, which is in some ways analogous to biological evolution. Dawkins proposes that units of information can propagate themselves like genes. "The new soup is the soup of human culture. We need a name for the new replicator or a unit of imitation. ‘Mimeme’ comes from a suitable Greek root, but I want a monosyllable that sounds a bit like ‘gene’. I hope my classicist friends will forgive me if I abbreviate mimeme to meme. If it is any consolation, it could alternatively be thought of as being related to ’memory’, or to the French word même. It should be pronounced to rhyme with ‘cream’."
Reception The Selfish Gene was extremely popular when published and it remains widely read. Proponents argue that the central point, that replicating the gene is the object of selection, usefully completes and extends Darwin's explanation of evolution. Peter Medawar wrote that it is "a most skillful reformulation of the central problems of social biology in terms of the genetical theory of natural selection. Beyond this, it is learned, witty and very well written." W. D. Hamilton wrote that "The book should be read, can be read, by almost anyone. It describes with great skill a new face of the theory of evolution." John Maynard Smith writes that "The Selfish Gene was unusual in that, although written as a popular account, it made an original contribution to biology."
The New York Times wrote "it's the kind of science writing that makes the reader feel like a genius." Tim Radford, reviewing it in 2012, wrote that "To re-read it is to be reminded of what an extraordinary achievement it was."
Ian McEwan writes "It hastened a sea change in evolutionary theory, it affected profoundly the teaching of biology, it enticed an enthusiastic younger generation into the subject, and spawned a huge literature, and eventually a new discipline - memetics. At the same time, and this is the measure of its achievement, it addressed itself without condescension to the layman. It did so provocatively, and with style."
Critiques