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How Fit Is E.O. Wilson’s Evolution?

I read E.O. Wilson’s 1975 book Sociobiology: The New Synthesis in 1979 while I was an undergraduate studying archaeology. Along with The Selfish Gene by Richard Dawkins (1976), Sociobiology transformed my view of the world, leading me away from a concern with the typology of stone tools and ceramics to deeper thoughts about human nature. As Wilson now expresses thirty-seven years later in the concluding pages of The Social Conquest of Earth, “History makes no sense without prehistory, and prehistory makes no sense without biology.” Whatever the specific arguments and ultimate merits of Sociobiology, it saved me from a life of measuring rim diameters and handle dimensions of ancient pots. Thank you, Professor Wilson.

At the time I did not appreciate E.O. Wilson’s stature as one of the greatest biologists of the twentieth century. I soon came to learn that in 1967 he was coauthor with Robert H. MacArthur of The Theory of Island Biogeography, which remains a key work for conservation today. I then learned that Wilson was the world authority on ants. Like so many others, I had gone through a “bug phase” as a boy and had even once declared to a primary school teacher that I wished to be an entomologist. I then began to appreciate the elegance of his prose. So E.O. Wilson was rapidly installed as an intellectual hero: someone who contributes to the highest-level theory about the nature of humanity, engages in fieldwork, analyzes data with meticulous erudition, and communicates to the layperson as effectively as to his scientific peers. Quite rightfully, he has been described as Darwin’s heir.

Now aged eighty-three, E.O. Wilson once described himself as never having grown out of his own childhood bug phase. Born in Alabama, he was awarded a Ph.D. in biology at Harvard in 1955, where he has remained for the entirety of his academic career, currently as Pellegrino Professor (Emeritus) in the Museum of Comparative Zoology. He has published a library of books and academic papers and been awarded a huge anthill of honors for his distinguished academic contributions to entomology, science, and the environment. These include the Crafoord Prize from the Royal Swedish Academy of Sciences, often described as the equivalent of a Nobel Prize for biosciences. Wilson has been twice awarded the Pulitzer Prize and has had a profound influence on twentieth- and twenty-first-century thought and culture. He is a champion of the preservation of biodiversity.

Sociobology remains Wilson’s most influential work. It argued that whether dealing with ants or humans, social behavior has a biological basis. It promoted the theory of inclusive fitness, or kin selection, as originally developed by William Hamilton in the 1960s as a means to explain seemingly altruistic behavior while remaining consistent with Darwin’s principle of natural selection. In The Social Conquest of Earth, Wilson describes how he had become “enchanted by the originality and proposed explanatory power of kin selection.”

In simple terms, this explains behavioral acts that are detrimental to the reproductive success of an individual as being a means to promote the success of genetically related individuals and hence maximizing the number of shared genes within future generations. It is, according to this hypothesis, better for your own biological fitness to sacrifice your own life to save the lives of three of your children (each of whom has 50 percent of your genes) or, even better, seven of your grandchildren (each of whom has 25 percent of your genes). Wilson went on to collaborate with Charles Lumsden on Genes, Mind, and Culture: The Coevolutionary Process (1981), one of the first serious attempts to explore the interaction between biology and culture.

Sociobiology was enormously controversial, not only among those in the humanities and social sciences who saw a biologist impinging on their academic territory, but also among many of his fellow biologists. In 1986 Stephen Jay Gould lambasted it, along with Genes, Mind, and Culture, in the pages of The New York Review.* Others have voted it the most influential book on animal behavior of the twentieth century.

I tend toward the latter view. So how marvelous it felt a few months ago to have received an e-mail from the man himself asking if he could reproduce a diagram relating to human evolution from one of my own publications in his forthcoming book, The Social Conquest of Earth. What an honor to then be invited to review the book for The New York Review. And how awfully disappointed I have been.

The Social Conquest of Earth considers the evolution of the two types of organisms that have indeed made a conquest of the earth—humans and social insects, notably ants. These show some remarkable similarities in their social behavior: it is difficult, for example, to avoid imposing the terminology of “building cities” and “practicing agriculture” onto the behavior of leafcutter ants. Needless to say, there are also profound differences in human and ant social behavior.

As one would expect from E.O. Wilson, he finds memorable ways of making the comparisons: if one were to pack together the estimated ten thousand trillion ants living today, they would form a cube less than a mile on each side—the same size as would be achieved by log-stacking the seven billion humans. Both packages could be easily hidden away in a small section of the Grand Canyon. Elsewhere Wilson helps us imagine an alien visitor to planet Earth some three million years ago who is amazed at the social insects but dismissive of the australopithecines, which appear to be on an evolutionary road to nowhere.

Social insects were fully evolved by 50 million years ago, with an evolutionary rate sufficiently slow to enable counter-evolution in other species—such as the sap-sucking insects that formed symbiotic partnerships with some ant species, or the pitcher plants that evolved to trap and digest ants—resulting in sustainable ecosystems. Homo sapiens, in contrast, only emerged 200,000 years ago, providing no time for the rest of the biosphere to adapt to its presence:

The rest of the living world could not coevolve fast enough to accommodate the onslaught of a spectacular conqueror that seemed to come from nowhere, and it began to crumble from the pressure.

Beguiling phrases such as this introduce the book, announcing a fascinating approach but setting off alarm bells in my mind about the picture of the human past being created, intentionally or otherwise.

The key similarity between humans and social insects is the characteristic of “eusociality,” defined by Wilson as “group members containing multiple generations and prone to perform altruistic acts as part of their division of labor.” This is, in fact, only characteristic of a small proportion of social insects, and of a mere 20,000 of the two million known insect species as a whole. The complexity of social life has certainly been a central theme in recent studies of human evolution, especially those concerning the brain, mind, and language. Although E.O. Wilson ignores most of that literature (at least it is not cited), he captures its general direction by describing human social strategies as being a “complicated mix of closely calibrated altruism, cooperation, competition, domination, reciprocity, defection, and deceit,” all of which depend upon feeling empathy, measuring emotions, and judging intentions.

As a path to eusociality, this is radically different from that taken by the instinct-driven, robotic insects. But once eusocial colonies are formed, Wilson contends, group selection becomes a key driver for both human and insect evolution. Group selection proposes that alleles—a particular form of a gene or group of genes—become fixed in a population because of the benefits they bestow on the whole group, regardless of the effects on the (inclusive) fitness of individuals—for instance, the benefit of being willing to sacrifice one’s life as a soldier.

Group selection was once popular among biologists, and then went entirely out of favor following critiques from William Hamilton and others who argued that social behaviors evolved entirely as the result of their benefits to the genetic fitness of individuals and those closely related to them—the theory known as kin selection, or inclusive-fitness theory. Group selection has recently made something of a return among a small group of biologists in the case of multilevel selection—a process combining selection at both the individual and group levels—for which Wilson has become a champion. As he writes:

In colonies composed of authentically cooperating individuals, as in human societies, and not just robotic extensions of the mother’s genome, as in eusocial insects, selection among genetically diverse individual members promotes selfish behavior. On the other hand, selection between groups of humans typically promotes altruism among members of the colony. Cheaters may win within the colony, variously acquiring a larger share of resources, avoiding dangerous tasks, or breaking rules; but colonies of cheaters lose to colonies of cooperators. How tightly organized and regulated a colony is depends on the number of cooperators as opposed to cheaters, which in turn depends on both the history of the species and the relative intensities of individual selection versus group selection that have occurred.

In drawing his evolutionary comparisons and contrasts, Wilson’s book alternates between sections devoted to humans and to social insects. There is an immense contrast of style and impact: the parts on humans are written as an external observer, a mere reviewer of literature, and suffer accordingly. The parts on social insects are the work of a key participant during the last half-century in research, enabling him to present a delightful blend of scientific account and personal experience.

The numerical facts are especially impressive: ants and termites originated 120 million years ago; one leafcutter ant can produce 150 million daughters. We learn how in 1967 Wilson received the first piece of fossil amber from the Mesozoic era, about 90 million years ago, to contain not one but two fossilized ants—twice as old as any seen before. It was, he describes, one of the most exciting moments of his life, so much so that he fumbled and dropped the piece. It broke into two—fortunately with one undamaged ant within each fragment. Elsewhere we read both how he enjoyed the sweet taste of scale insect [i.e., aphid] excrement during his hikes through the New Guinea rainforest and also his reflections when watching harvester ants on Jerusalem’s Temple Mount, pondering how Solomon would have sat there watching precisely the same species at work.

Such accounts must be the tiny termite tip of a million and more stories that E.O. Wilson could relate. All readers will want more—fortunately there are plenty available within his other books, notably in Naturalist, his 1994 autobiography. Any more within the The Social Conquest of Earth would have been a distraction because Wilson is seeking to convey his bold theoretical perspective on the evolution of eusociality.

At the heart of the book lies Wilson’s rejection of inclusive-fitness theory in favor of group selection. This is not a trivial matter: inclusive fitness has been the preeminent theory in social evolution for half a century and Wilson himself describes it as a virtual dogma. Perhaps for that very reason he does not mince his words, writing about “the misadventure of inclusive-fitness theory” and how this is a “phantom mathematical construction that cannot be fixed in any manner that conveys realistic biological meaning.” A reader cannot fail to be impressed by such conviction coming from such a distinguished biologist.

  1. *

    Stephen Jay Gould, “ Cardboard Darwinism,” The New York Review, September 25, 1986. 

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