The Selfish Gene



The Selfish Gene is a very popular and somewhat controversial book on evolutionary theory by Richard Dawkins, published in 1976. The phrase "selfish gene" in the title of the book was coined by Dawkins as a provocative way of expressing the gene-centric view of evolution, which holds that evolution is best viewed as acting on genes, and that selection at the level of organisms or populations almost never overrides selection on genes. More precisely, an organism is expected to evolve to maximise its inclusive fitness – the number of copies of its genes passed on globally (rather than by a particular individual). As a result, populations will tend towards an evolutionarily stable strategy. The book also coins the term meme, for a unit of human cultural evolution analogous to the gene, suggesting that such "selfish" replication may also model human culture, in a different sense. Memetics has become the subject of many studies since the publication of the book.

"Selfish" genes
Describing genes with the term "selfish" is not meant to imply that they have actual motives or will – only that their effects can be accurately described as if they do. The contention is that the genes that get passed on are the ones whose consequences serve their own implicit interests, not necessarily those of the organism, much less any larger level. Some people find this metaphor entirely clear, while others find it confusing, misleading or simply redundant to ascribe mental attributes to something that is mindless. For example, Andrew Brown has written:

''"Selfish," when applied to genes, doesn't mean "selfish" at all. It means, instead, an extremely important quality for which there is no good word in the English language: "the quality of being copied by a Darwinian selection process." This is a complicated mouthful. There ought to be a better, shorter word – but "selfish" isn't it.''

A crude analogy can be found in the old saw about a chicken being just an egg's way of making more eggs. In a similar inversion, Dawkins describes biological organisms as "vehicles", with genes as the "replicators" that create these organisms as a means of acquiring resources and copying themselves. At the level of organisms, we can see genes as being for some feature that might benefit the organism, but at the level of genes, the sole implicit purpose is to benefit themselves. A related concept here is the extended phenotype, in which the consequences of the genes to the environment outside the organism are considered.

Genes and selection
Dawkins proposes that genes that help the organism they happen to be in to survive and reproduce tend to also improve their own chances of being passed on, so – most of the time – "successful" genes will also be beneficial to the organism. An example of this might be a gene that protects the organism against a disease, which helps the gene spread and also helps the organism. There are other times when the implicit interests of the vehicle and replicator are in conflict, such as the genes behind certain male spiders' instinctive mating behaviour, which increase the organism's inclusive fitness by allowing it to reproduce, but shorten its life by exposing it to the risk of being eaten by the cannibalistic female. Another good example is the existence of segregation distortion genes that are detrimental to their host but nonetheless propagate themselves at its expense. Likewise, the existence of junk DNA that provides no benefit to its host, once a puzzle, can be more easily explained. A more controversial example is aging, in which an old organism's death makes room for its offspring, benefiting its genes at the cost of the organism.

These examples might suggest that there is a power-struggle between genes and their host. In fact, the claim is that there isn't much of a struggle because the genes usually win without a fight. Only if the organism becomes intelligent enough to understand its own interests, as distinct from those of its genes, can there be true conflict. An example of this would be a person deciding not to breed because they'd be miserable raising children, even though their genes lose out due to this decision.

When looked at from the point of view of gene selection, many biological phenomena that, in prior models, were difficult to explain become easier to understand. In particular, phenomena such as kin selection and eusociality, where organisms act altruistically, against their individual interests (in the sense of health, safety or personal reproduction) to help related organisms reproduce, can be explained as genes helping copies of themselves in other bodies to replicate. Interestingly, the "selfish" actions of genes lead to unselfish actions by organisms.

Prior to the 1960s, it was common for such behaviour to be explained in terms of group selection, where the benefits to the organism or even population were supposed to account for the popularity of the genes responsible for the tendency towards that behaviour. This was shown not to be an evolutionarily stable strategy, in that it would only take a single individual with a tendency towards more selfish behaviour to undermine a population otherwise filled only with the gene for altruism towards non-kin.

Acclaim and criticism
The book was extremely popular when first published, and continues to be widely read. It has sold over a million copies, and been translated into more than 25 languages. Proponents argue that the central point, that the gene is the unit of selection, usefully completes and extends the explanation of evolution given by Darwin before the basic mechanisms of genetics were understood. Critics argue that it oversimplifies the relationship between genes and the organism.

Most modern evolutionary biologists accept that the idea is consistent with many processes in evolution. However, the view that selection on other levels, such as organisms and populations, seldom opposes selection on genes is more controversial. While naive versions of group selectionism have been disproved, more sophisticated formulations make accurate predictions in some cases while positing selection at higher levels. Nevertheless, the explanatory gains of using sophisticated formulations of group selectionism as opposed to Dawkins' gene-centered selectionism is still under dispute.

Some biologists have criticised the idea for describing the gene as the unit of selection, but suggest describing the gene as the unit of evolution, on the grounds that selection is a "here and now" event of reproduction and survival, while evolution is the long-term trend of shifting allele frequencies.

Another criticism of the book, made by the philosopher Mary Midgley in her book Evolution as a Religion, is that it discusses philosophical and moral questions that go beyond the biological arguments that Dawkins makes. For instance, humanity finally gaining power over the "selfish replicators" is a major theme at the end of the book. Dawkins has pointed out that he is only describing how things are under evolution, not endorsing them as morally good. Nevertheless, the gap between "is" and "ought" is not always as clearcut as purported, and very easily transgressed.

The idea is sometimes mistakenly believed to support genetic determinism. This is incorrect: knowing that an organism carries a particular allele, we might be able to say that the organism is more likely than otherwise to behave in a certain way, but its actual behaviour will depend on its environment and its developmental history. Of course, while this argumentation eschews genetic determinism, it does not overcome determinism in a wider sense, for environmental factors will still restrict the behavior of the organism. Dawkins is quick to point out that, although humans may be influenced by their genes, they are not controlled by them. Even further from Dawkins' concept is the misunderstanding of the idea as predicting (or even prescribing or justifying) that human behaviour must inevitably be "selfish" in a moral or ethical sense.

Editions
The Selfish Gene was first published in 1976 in eleven chapters with a preface by the author and a foreword by Robert Trivers. A second edition was published in 1989. This edition added two extra chapters, and substantial footnotes to the preceding chapters, reflecting new findings and thoughts. It also added a second preface by the author, but the original foreword by Trivers was dropped. In 2006, a 30th anniversary edition was published which reinstated the Trivers foreword and contained a new introduction by the author (alongside the previous two prefaces), and also some selected extracts from reviews at the back.