“Darwin is the one who changed everything, our self-conception; greater than Copernicus,” Wilson told me. “This guy is irritatingly correct, time and time again, even when he has limited evidence.” In Darwin’s mold, the thrust of Wilson’s life work has been aimed at changing humankind’s self-conception. Indeed it can be difficult, from today’s vantage point, to see what much of the fuss of the 1970s was about, so thoroughly has the Wilsonian idea that our genes shape our nature penetrated the mainstream.
This reality is illustrated, among countless possible examples, in Francis Fukuyama’s most recent book, The Origins of Political Order: From Prehuman Times to the French Revolution. Rejecting the views of classic political philosophers like Hobbes, Locke, and Rousseau that primitive humankind started out as a collection of scattered, unorganized individuals, Fukuyama writes: “Human sociability is not a historical or cultural acquisition, but something hardwired into human nature.” Nowhere is Wilson, who pioneered this view, even mentioned.
The current controversy results from another bid by Wilson to overturn conventional scientific wisdom. For more than four decades, evolutionary biology has been dominated by a school of thought known as “kin selection,” which postulates that some species arrive at cooperative behavior and a complex division of labor as a matter of reproductive strategy among close relatives. In other words, self-sacrifice and other forms of altruism are really driven by what might be described as a coolly selfish calculation: cooperation among related individuals favors the reproduction of kin and hence the propagation of shared genes. This notion was established in a famous mathematical rule laid out by W. D. Hamilton in 1964, Rb>c, which means that genetic benefits (b) realized by helping a relative (R) pass on his or her genes must be greater than the cost (c) of assisting that relative in order for the behavior to be favored by natural selection.
Wilson believes that this whole theory has been a wrong turn, intellectually, and that this bedrock concept, with major implications for understanding our own nature, is overdue for radical revision.
The furor erupted with the publication, in the scientific journal Nature in August 2010, of an article written by Wilson and two co-authors, Martin A. Nowak and Corina E. Tarnita, both of Harvard. Titled “The Evolution of Eusociality,” it amounted to a frontal challenge to a key concept of kin-selection theory, called “inclusive fitness.” Among other things, inclusive fitness says that species like ants have become highly social, and that the sisters that make up the overwhelming bulk of any colony cede the right to reproduce to the queen, because of the extraordinarily high degree of genetic relatedness between the sisters, which surpasses even that between mother and daughter.
Ants and humans are among the very few “eusocial” animals—the most highly social creatures in the history of life on Earth, capable of building complex societies in which individuals specialize in various activities and sometimes act altruistically. Darwin himself, in his most influential book, The Origin of Species, recognized the vexing question of why female ants would sacrifice the right to reproduce rather than seek to pass along their own genes as the greatest challenge to his theory of evolution. Now, employing advanced mathematics involving evolutionary game theory and population genetics, the authors of the controversial Nature article have shaken up the evolutionary-biology establishment by rejecting kin selection, and claiming that the close genetic similarity of sister ants is not mathematically necessary to explain their “eusociality”—and, indeed, is not the cause of it.
The mathematical heavy lifting comes from Nowak and Tarnita, showing, in the words of Nowak, that “simple versions of Hamilton’s rule … are almost always wrong,” and that recent efforts to create more-generalized versions of the rule are of no help in explaining evolution. But the proposed new interpretation of what causes ants and a few other species to become highly social, to the point of intricate specialization and even self-sacrifice, or altruism, is classic Wilson. “The causative agent,” the authors wrote, “is the advantage of a defensible nest.” Eusocial creatures are driven to cooperate not by their relatedness, in other words, but by the advantages that accrue to any group from the division of labor. As natural circumstance forced individuals to interact, certain cooperative traits became advantageous, and proliferated, in a handful of cases.
In support of their attack on kin selection, the authors invoke the rarity of eusociality across the animal kingdom, even among species in which the genetic similarity of kin is extremely high. Among species that use clonal reproduction, for example, only one major group, the gall-making aphids, are known to be eusocial. What’s more, eusocial behavior can occur—even among insects—in the absence of kinship. One example is the propensity of certain solitary bees to behave like eusocial bees when they are forced to live together in the laboratory. “The coerced partners proceed variously to divide labor in foraging, tunneling, guarding.”
The authors conclude that a very small number of species simply seem to be genetically “spring-loaded,” or “strongly predisposed” to the development of eusociality in conditions where natural selection favors it. The article then ropes humans into the picture in its last and most provocative sentence: “We have not addressed the evolution of human social behavior here, but parallels with the scenarios of animal eusocial evolution exist, and they are, we believe, well worth examining.” Until now, the conventional wisdom on the social evolution of humans has focused on the growth and development of the brain, not on the existence of a social gene or set of such genes that may have spring-loaded humans for civilization—or for altruism. Yet Wilson and his co-authors imply that such genes very likely exist.
The outcry from the evolutionary-theory establishment, including luminaries in the field ranging from Richard Dawkins to Robert Trivers, was exceptionally fierce, including unusually personal attacks. One of several critical letters to the editor published by Nature was signed by 137 scientists. Another letter called the authors’ findings “largely irrelevant.”
Elsewhere, commentators objected that Nature should never have published the article, and only did so because Wilson’s name was attached to it. Some claimed that the authors had not fully understood or had willfully misrepresented kin-selection theory. One commentator even wrote off Wilson for his “senescence.” On his blog, Jerry A. Coyne, a leading figure in the field and a professor in the department of ecology and evolution at the University of Chicago, voiced pity for Tarnita, a Romanian theoretical mathematician who works at Harvard’s Program for Evolutionary Dynamics. Calling the paper “dreck,” he said that it “will always cast a shadow over her career.”
“Nowak et al.,” as the authors are called in the Nature back-and-forth, have firmly held their ground. “Inclusive fitness theory,” they wrote in their published response, “is neither useful nor necessary to explain the evolution of eusociality or other phenomena.” In an e-mail to me, Tarnita wrote about the criticisms directed at her:
Coming from a mathematics background and having contributed a mathematical argument to this discussion, I am not one to be impressed by such statements, unless they are supported by an actual mathematical refutation of my arguments. So far there has been none.
In collaborating with Nowak and Tarnita, Wilson was in effect reprising a tactic that led to his first major theoretical triumph, with island biogeography—joining forces with talented mathematicians. In that instance, in the early 1960s, he teamed up with the late Robert H. MacArthur, whose work on population growth and competition, Wilson says, made him the most important ecologist of his generation.
“Nothing is more attractive to me than a muddled domain awaiting its first theory,” Wilson wrote in Biophilia:
I feel most at home with a jumble of glittering data and the feeling that they might be fitted together for the first time into some new pattern. This inclination made me especially compatible with mathematicians. I became fascinated with the way they think, why they should be so much better at quantitative reasoning than I, what difference it made in the end, why I should be the one so often to suggest moving in a particular direction, but then even more frequently not be able to do so, and finally how different everything looked after a little progress had been made.