Selfish Gene, The
KeywordsEvolutionary Psychological Science Inclusive Fitness Stable Evolutionary Strategy Reciprocal Altruism Extended Phenotype
A seminal text in evolutionary biology that articulates the gene-centered view of evolution by natural selection, explains how self-interested genes can give rise to altruism, and introduces the meme.
The Selfish Gene (1976) was English ethologist and evolutionary biologist Richard Dawkins’s first book. Drawing on the theory developed by G. C. Williams (1966), Dawkins asserts that the gene is the primary unit of natural selection and criticizes group selection accounts. Another goal of the book was to “examine the biology of selfishness and altruism” (p. 1) by combining theories of inclusive fitness, such as kin selection, with the gene-centered view of natural selection. Dawkins also coined the meme as a unit of human cultural evolution. The Selfish Gene, now in its fourth edition, has remained an influential articulation of evolutionary theory and has been employed by evolutionary psychological science as a foundational theoretical perspective (e.g., Tooby and Cosmides 1992).
The Gene-Centered View of Life: Replicators and Gene Machines
Biologists since Darwin have agreed that evolution by natural selection occurs by the differential survival and reproduction of self-replicating entities. However, as explained early in The Selfish Gene, there has been debate as to the level(s) on which selection acts, with some advancing the possibility of selection between groups in addition to selection between individual organisms. Dawkins expresses skepticism toward group selection accounts, arguing groups lack “longevity, fecundity, and copying-fidelity” (p. 35), the key attributes of a replicator. The gene, by contrast, exemplifies those properties. Defined as a given stretch of DNA, genes are capable of persisting across generations, exist in duplicate copies found across individuals of a species, and self-replicate with a high degree of accuracy. Such attributes allow Dawkins to conclude that the gene is the “largest practical unit of natural selection” (p. 36): it is the fittest gene which outcompetes its rivals (alleles) and differentially propagates into the next generation.
All successful genes are then necessarily selfish in the sense that they seek replication at the expense of their competitors. A gene may gain an advantage over another should it code for proteins that compose what Dawkins terms survival machines, or vehicles, that enhance that gene’s capacity to exploit the environment and reproduce. Early in the evolution of life, these vehicles consisted of relatively simple chemical barriers, but eventually “both animals and plants evolved into many-celled bodies” as “selection has favored genes that cooperate together” (p. 46). Central to Dawkins’s thesis, therefore, is that a successful gene is “compatible with, and complementary to, the other genes with whom it has to share a long succession of bodies” (p. 84). In brief, genes are replicators that cooperate to create machines, living bodies, which enhance their individual reproduction. Selection then favors the fittest set of genes based on their phenotypic, expressed, effects on the world.
The Evolution of Altruism
Next, Dawkins references the work of W. D. Hamilton (1964) to illustrate how altruism may arise between individual organisms. Altruism is defined as a behavior which confers a fitness benefit to another at a cost to one’s own fitness. For example, a honeybee may launch a suicide attack on an intruder in support of her hive mates. The selfish gene theory, Dawkins argues, best predicts such phenomena because a given gene exists as duplicates found across individuals of a species. As a consequence, selection would favor a gene that was able to promote its duplicate’s fitness in another body, and “this would appear as individual altruism but it would be brought about by gene selfishness” (p. 87). Genes therefore may be selected to promote their inclusive fitness, all copies, in addition to their personal fitness, a particular copy.
This is observed in kin selection. First note that there is a comparatively higher probability that close relatives, such as bees from the same hive, share a particular gene. Altruistic behavior may evolve should an action result in a net gain in gene replication, even at the expense of a particular individual’s genes: a honeybee’s costly defense of her relatives is ultimately an act that benefits the survival and reproduction of her genes across bodies. Kin-directed altruism extends into parent-offspring relations as well. Indeed, a parent can invest in its offspring at an expense to itself, but to the net benefit of the genes shared between the two (although conflict may arise between parent and child concerning the optimal distribution of investment; see Trivers (1972)).
In a later chapter of The Selfish Gene, Dawkins also connects the gene’s-eye view of natural selection with work from economics, political science, and psychology to explain the evolution of reciprocal altruism. This is where an individual behaves altruistically toward a non-kin other, given that the roles are reversed at some point in the future. Such situations are often modeled after the prisoner’s dilemma, where two agents both have the option to cooperate or defect. Typically the payout structure of the different outcomes favors the decision to defect. However, should the scenario be played out repeatedly over an indefinite period of evolutionary time, with offspring as the payoff, selection may favor the evolution of mutual cooperation. Under such conditions, simulation studies reveal that a simple “tit for tat” strategy of default cooperation coupled with punitive recrimination of defectors evolves as a stable evolutionary strategy in iterated games of prisoner’s dilemma. Empirical examples that Dawkins cites include the regurgitation of blood from a successful vampire bat to a less fortunate conspecific after a hunt. Recent laboratory evidence additionally suggests humans have a host of evolved psychological mechanisms regulating reciprocal exchange relationships (Kaplan et al. 2012).
Memes: The Cultural Replicators
The Selfish Gene also devotes a chapter to human cultural transmission and evolution. Change over time in human language and technology, Dawkins notes, exhibits parallels to genetic evolution. Indeed he writes that an evolutionary process is inevitable given the existence of any self-replicating entity. Genes are one such replicator, and in the domain of human culture Dawkins proposes the existence of a replicator he calls the meme. These are ideas or beliefs that “propagate themselves… by leaping from brain to brain” (p. 192) and constitute the unit of cultural evolution. Like in genetic natural selection, the meme that is most fit to its environment, in this case by appealing to human psychology, differentially reproduces across the minds of individuals. Successful memes then band together, forming clusters that mutually reinforce their transmission. Examples of such meme complexes may include religious doctrine, a symphony, or scientific theory. Dawkins’s meme spawned its own field of study, memetics, whose proponents include philosopher of mind Daniel C. Dennett. Critics, however, argue that memes do not replicate from mind to mind with the requisite accuracy (e.g., Richerson and Boyd 2005).
Richard Dawkins’s The Selfish Gene greatly popularized the gene-centered view of evolution and has remained influential across disciplines. In biology, Dawkins expands on several of the book’s arguments in his follow-up, The Extended Phenotype (1982). Here, he describes how genes have consequences that extend far outside the body they inhabit, for instance, in the creation of artifacts like a bird nest or in the actions of parasites. Furthermore, The Selfish Gene bridged the life and behavioral sciences, foreshadowing the development of evolutionary psychological science. Specifically Dawkins provides early speculation that “our basic psychological attributes and tendencies” (p. 192) are the product of evolution, including kin selection and selection for reciprocal altruism, assertions later supported by entire literatures. Highly focused yet wide-ranging, the selfish gene theory continues to inform research connected to the life, brain, and behavioral sciences.
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