Essence of Selfish Gene Theory

Dawkins has spent much of his career defending a particular view of Darwinism. This so-called selfish gene view grew out of work in the 1960s by George Williams and William Hamilton. While Darwin argued that evolution involves a kind of survival of the fittest, Hamilton, Williams, and their heirs argued that it’s the fittest gene that matters, not the fittest organism. To see what this means, consider an example. When a small bird spots a hawk overhead it will often issue an alarm call, warning its flock-mates of the predator’s presence. The odd thing is that this behavior—which we’ll assume is instinctive, that is, genetically based—is “altruistic.” By sounding the alarm, a bird may well save its flock-mates but it simultaneously calls attention to itself, increasing the odds that it will be attacked by the hawk. How could such a behavior evolve?

If you think of Darwinism in traditional terms—as competition among different organisms—the answer isn’t obvious. A bird who sounds a call (and so perhaps gets eaten) is unlikely to have more offspring than a bird who keeps quiet (and so probably avoids getting eaten). And having more offspring is what Darwinism was supposed to be all about. But if you think of Darwinism in selfish gene terms— as competition among different genes —the answer is clearer. A gene that makes a bird emit an alarm may decrease the odds that the calling bird survives but it can increase the odds that the gene for alarm-calling survives. The reason is that the flock-mates who are saved by the alarm are, like all flock-mates, likely to be related to the caller; and relatives, by definition, tend to carry the same genes, including the gene for sounding the alarm. In effect, then, the alarm-call gene is warning—and saving— copies of itself. Those copies just happen to reside in other organisms. The counterintuitive conclusion is that a gene that sometimes causes an organism to sacrifice itself can increase its frequency by natural selection. The alternative kind of gene—one for not emitting an alarm call—can decrease in frequency, since such genes are on average less likely to be passed on to the next generation.

To Dawkins and other advocates of the selfish gene view, such examples reveal something deep about Darwinism: natural selection acts at the level of competing genes, not competing organisms.

—H. Allen Orr, NYBooks[^1]