Evolutionary biologists increasingly accept that genes are selfish. But what does this mean? Clearly genes do not have personal motivations, and even if they did, they could not achieve their designs without cooperation of the bodies in which they reside. In the most general sense, genes are merely blueprints, or, better, recipes, for the production of proteins. As such they influence the anatomy and physiology of living things including not only structural proteins but also enzymes and other factors that underlie the functioning of organisms. Genes ultimately affect the structure of kidneys, as well as the structure of nervous systems. Genes thus influence kidney function, just as they influence central nervous system function. When the central nervous system functions, behavior results. In this sense, genes are intimately connected to behavior, no less than they are to the physiology and structure of our internal organs.
Organisms are typically rather short-lived. Although they occupy the most obvious stage of the ecological and evolutionary theater, and natural selection appears to act on organisms whenever some reproduce differentially relative to others, the fact remains that natural selection among organisms is only important in the evolutionary sense insofar as it results in the disproportionate replication of some genes relative to others. Individual bodies themselves do not persist in evolutionary time; genes do. In fact genes are potentially immortal whereas bodies are not.
Selfish Genes and Modern Genetics
At the time of Charles Darwin (1809–1882), genetics was unknown, and so the focus of early evolutionary biology was on bodies. With the rise of Mendelian genetics and, subsequently, the field of population genetics, it became possible to trace the consequences of differential reproduction on their ultimate units, the genes themselves. Recognition of DNA as the genetic material, along with identification of its structure and the rise of modern genomic technology, has enhanced our understanding and also clarified the importance of focusing on these crucial units. When a hippo or a human being has a certain fitness, this means that his or her DNA is projected into the future with a given degree of success.
The term selfish, in relation to genes, is no more than a useful verbal short-hand. Selfishness simply refers to success in contributing to a particular gene's own replication. Natural selection rewards those genes that produce a successful body by causing more of the genes that influence the production of that body to be projected into the future. In this regard a successful body is one that metabolizes efficiently, that pumps blood successfully, that regulates its internal environment in a way conducive to life, and that also behaves in a manner that maximizes its success in reproducing, and/or in contributing to the reproduction of its component genes in the other major way available to it: by contributing to the success of genetic relatives, with the importance of each relative devalued in proportion as it is more distantly related (i.e., in direct proportion as a gene in a subject individual is likely to be present, by shared descent, in the body of another).
A key event in the development of selfish gene thinking was the recognition by British geneticist William Hamilton (1936–2000) that reproduction itself is only a special case of the more general phenomenon whereby genes contribute to their own replication. In a sexual species, reproduction occurs at some cost to the parent—in time, energy, risk—for which the sole evolutionary payoff is that each of the parent's genes has a 50 percent probability of being present in each offspring, and thereby are given a boost into succeeding generations. Hamilton observed that although reproduction is not normally considered selfish, in fact it is, at the level of genes. Moreover it is only because of the selfish payoff to the genes in question that reproduction is favored by natural selection in the first place!
Unlike the usual, negative implication of the word selfish, when applied to the attributes of genes, the term has no direct ethical implications. Living things are considered to behave in a manner that maximizes their inclusive fitness, which is simply the net effect of an act on identical genes present in other bodies. As a result selfish gene theory suggests that behavior that is selfish at the gene level typically involves actions that are altruistic at the level of bodies.
Hamilton effectively demonstrated that much seemingly altruistic behavior can be explained by this gene-centered perspective. Individual genes can promote their evolutionary success not only by helping produce offspring—new bodies within which some of these genes will reside—but also by contributing to the success of other individuals that have a probability of containing the genes in question. These other individuals are genetic relatives; indeed, a genetic relative is defined as an organism with an above-average probability of containing genes already present in a designated individual. For example, alarm-calling, whereby individuals who sense an approaching predator announce their discovery, that is directed preferentially toward genetic relatives. This can be selected for even if it reduces the likely survival of the alarm-caller so long as it increases the prospects that these relatives—and the alarm-calling genes within them—will survive and reproduce.
British biologist Richard Dawkins has been especially successful in explaining and popularizing this perspective, notably through his highly influential book, The Selfish Gene (1989). Dawkins argued that genes are essentially replicators whose biological role is to make additional copies of themselves. Those that succeeded in doing so went on to write the continuing history of life. Whereas early in evolutionary history replicators presumably floated freely in an organic soup, as natural selection continued, some discovered—quite by chance—that they were more successful by surrounding themselves with cell membranes and eventually, by aggregating together into multicellular bodies. Accordingly these bodies served, and still serve, as mere survival vehicles for the replicators.
This view is counter-intuitive because human beings subjectively experience themselves as the center of their own worlds, and therefore assume that their bodies—and not their genes—are equally the center of evolutionary concern. But bodies do not persist through evolutionary time. Although bodies can be selected for in the very short term, in that certain individuals are more reproductively successful than others, in the long term, these bodies are only vehicles for the differential success of their constituent genes, which replicate by virtue of the actions of the bodies in which they are enclosed.
Selfishness versus Altruism: A False Dichotomy
Critics of sociobiology and evolutionary psychology—both of which disciplines have been strongly influenced by the concept of selfish genes—often assume that this perspective implies that selfishness is more natural than altruism. The assumption has two significant flaws. First it suggests that identifying a trait as natural means that it is necessarily good, a view that was criticized by English philosopher David Hume (1711–1776), and, in the twentieth century, by philosopher George Edward Moore (1873–1958), who emphasized that is does not necessarily imply ought. Moore called this the naturalistic fallacy, and he argued that it is not philosophically or ethically defensible. Although many biologists—including Darwin—have maintained that morality is rooted in a natural moral sense, it is one thing to see morality as somehow deriving from one's biological heritage, quite another to validate behavioral tendencies simply because they are natural. It may be natural to respond violently to frustration, or in certain situations of competition, but is debatable whether in such cases, naturalness confers any ethical legitimacy.
Second, the suggestion that selfishness is somehow more natural than altruism ignores the crucial recognition that underlies all of selfish gene theory: the biological reality that genes cannot and do not behave in a vacuum, but only in the context of bodies. As such when a gene predisposes its body to behave selfishly (from the perspective of the gene), it often does so by inclining that self to act altruistically at the level of bodies. When parents provide food for their offspring, defend them against predators, or invest time and energy in their training, they may well be acting selfishly at the level of shared genes between parent and child, but altruistically insofar as individuals are behaving benevolently toward one another. Accordingly selfish genes need not behave selfishly!
The technology of cloning, stem cell research, and allied genomic sciences—including the identification of the human genome—has made considerations of human genes increasingly real. When developmental geneticists or evolutionary theorists speak of genes, they are increasingly able to speak authoritatively about specific DNA sequences, on identifiable chromosomes. It nonetheless does not seem likely that technology will permit the isolation of specific selfish or altruistic genes because selfish behavior does not exist as such, but rather, as a constituent of other characteristics and tendencies. For example, as discussed above, alarm-calling, which is a common textbook example of animal altruism, enhances the likely survival of others but at some increased risk to the alarm-caller. Alarm-calling need not be a result of generalized altruistic tendencies; rather it could derive from enhanced watchfulness due to anxiety, or even more acute eyesight, or a greater tendency to scan the surroundings for any number of reasons. Neither altruism nor selfishness per se, isolated as a generalized behavior trait, need be involved. The likelihood, therefore, is that advances in genetic technology will continue to elaborate genetic influences on behavior (just as they will with respect to proclivities for disease), without teasing out selfish genes as such. This, however, would not negate the scientific cogency of the concept, or even its genuine reality, because genes are selfish whenever they contribute to their own evolutionary success, without necessarily inducing their bodies to behave in an overtly self-aggrandizing manner.
Ethical Considerations Regarding Selfish Genes
Traditionally selfish behavior is considered unethical and its alternative, altruism, has been lauded as highly ethical. When biologists speak of selfish and altruistic behavior, they are simply defining these actions by their fitness consequences, and are not implying moral judgments. At the same time, one can speculate that the widespread, cross-cultural valuing of altruism and derogation of selfishness may itself derive from recognition that the living world inclines toward selfishness (at least at the level of genes) to a degree that may make exhortations to the contrary especially worthwhile.
Based on this cynics might point out that social and ethical systems may emphasize the desirability of altruism because of the payoff such behavior confers on others: Most people would be better off if others could be persuaded to be more altruistic, while they themselves remain comparatively selfish! Similarly biologists might point out that, as argued above, the boundaries between selfishness and altruism are unclear and often interpenetrating. Ethicists might emphasize that whereas evolutionary phenomena are crucially important to learn about, they are not suitable for learning from: Insofar as natural selection has produced human beings, along with other organisms, as the survival vehicles for selfish genes, the evolutionary process simply promotes whatever works. It is the responsibility of human beings to decide how they choose to assess such inclinations, and how, if at all, they elect to be influenced by that knowledge.
DAVID P. BARASH
Alcock, John. (2001). The Triumph of Sociobiology. New York: Oxford University Press. An explanation of the scientific underpinnings as well as the successes of sociobiology and its selfish genes approach.
Barash, David P. (2001). Revolutionary Biology: The New, Gene-Centered View of Life. New Brunswick, NJ: Transaction Publishers. A nontechnical but scientifically accurate account of how a selfish genes perspectives helps illuminate human behavior in particular.
De Waal, Frans B. M. (1996). Good Natured. Cambridge, MA: Harvard University Press. An account of various prosocial behaviors in nonhuman primates, showing that a selfish genes perspective is not incompatible with animal benevolence.
Hamilton, William D. (2002). The Narrow Roads of Gene Land. New York: Oxford University Press. A compilation of the important technical papers written by the founder of selfish gene thinking, with useful commentary.
Trivers, Robert L. (2003). Natural Selection and Social Theory. Cambridge, MA: Harvard University Press. A compilation of the important technical papers by one of the most original practitioners of selfish gene thinking, along with personal commentary.
Williams, George C. (1998). The Pony Fish's Glow: And Other Clues to Plan and Purpose in Nature. New York: Basic Books. An exceptionally lucid treatment of the benefits and limits of selfish gene thinking.
Wilson, Edward O. (1975). Sociobiology: The New Synthesis. Cambridge, MA: Harvard University Press. The now-classic summarization of sociobiology, which generated much of the controversy, and also brought together many important ideas, previously isolated.
a. that extra DNA separates the genes so as to increase the cross-over frequency;
b. that the possibility of varying the total amount of DNA per cell allows the control of cell volume and cell growth rate; and
c. the selfish DNA hypothesis) that selection acts within the genome favouring any method by which DNA may more rapidly replicate itself, and that this can be better achieved if phenotypic expression can be bypassed.
This is achieved, it is proposed, by DNA spreading laterally so as to be duplicated at new loci elsewhere in the genome. In this way the DNA may be viewed as acting ‘selfishly’, since the apparently surplus DNA confers no advantage on the organism bearing it and therefore supplying the materials from which it is made. See also SELFISH GENES.