Of all the achievements of life on land, few are stranger or more consequential than the insect society. A colony of ants, of termites, or of the social bees and wasps is not a crowd, not a herd, not a swarm in the loose sense of a great many creatures happening to occupy the same patch of ground. It is an organized whole. And the recognition of that fact — that a mass of small, separate, short-lived creatures can behave, and can be understood, as a single coordinated being — is the thread that runs through the whole of Edward O. Wilson's life in science. He came back to it again and again across five decades, from his first great synthesis in 1971 to the sweeping restatement he wrote with Bert Hölldobler near the end of his working life. It was the idea that made him, and it is the right place to begin a reader of his work, because nearly everything else he thought about the living world grew from it.
This chapter follows that idea from its foundations: what makes an insect society a society rather than a gathering; how a colony divides its labor and governs itself without a governor; how thousands of individuals are welded into one functioning entity; and how, over Wilson's career, a suggestive metaphor — the colony as a kind of organism — hardened into an explicit and productive scientific concept, the superorganism. Along the way it introduces the puzzle that would occupy Wilson to the end of his days, the puzzle of how creatures that surrender their own reproduction to serve others could ever have been produced by a process as selfish, on its face, as natural selection.
Wilson began, in The Insect Societies (1971), by drawing a hard line. Not every group of insects is a society. A swarm of gnats dancing in the evening light is not one; an aggregation of overwintering beetles is not one; a honeybee hive most certainly is. What separates the true societies from the mere gatherings, he argued, is a specific and demanding combination of traits. There must be cooperative care of the young, so that individuals tend offspring not necessarily their own. There must be an overlap of generations, so that parents and their grown offspring live together in the same nest and the society persists through time. And there must be, most decisively of all, a reproductive division of labor: some members breed, and others, though physically capable of it in many cases, do not, devoting themselves instead to labor on behalf of the colony.
This third condition is the crux, and Wilson placed it at the center of his subject from the very first pages. Later given the name eusociality — true sociality — it describes the deepest of the divisions that structure an insect society. It means that in a colony of ants or termites the great majority of individuals are workers who will never reproduce, who spend their lives foraging, building, nursing, and defending, and who leave no direct descendants of their own. That surrender of personal reproduction is the central problem of the entire field. Under the plainest reading of Darwin, an individual that forgoes reproduction ought to be swiftly eliminated, its self-denying tendencies dying with it. That insect societies are built precisely upon such individuals — that they are not merely common but ecologically triumphant — is the paradox Wilson set himself to explain, and it is worth keeping in view through all that follows, for it is the engine of the whole inquiry.
The organizing conviction of that first book, and of everything that came after, was that a colony can be analyzed as a unit — an entity possessing properties that none of its members possess alone. An ant colony has an architecture: a queen, a force of sterile workers, a population of developing brood, arranged and maintained in a nest of sometimes astonishing complexity. It has something like a physiology, a division of labor that keeps it fed, clean, defended, and reproducing as surely as organs keep a body alive. Wilson treated this organismal perspective not as a poetic conceit but as a working analytical stance, a way of asking questions. It shaped how he approached caste, communication, and reproduction, and it anticipated, by nearly forty years, the explicit superorganism he and Hölldobler would eventually develop in full. The colony, he saw, was a level of biological organization in its own right, sitting above the individual as the individual sits above the cell, and demanding to be studied on its own terms.
It is worth pausing, before going further into the machinery of these societies, on the sheer scale of what that machinery has accomplished, because it supplies the stakes of the whole inquiry. The social insects are not a marginal curiosity. Though they make up only a small fraction of all insect species, they dominate the terrestrial world in the one currency that matters most in ecology, which is living mass. Wilson and Hölldobler assembled the striking estimates: in many habitats, and above all in the tropical forests, the ants and termites together may compose a large fraction of the entire animal biomass, outweighing all the vertebrates — all the mammals, birds, reptiles, and amphibians combined — that share the same ground. The social insects turn the soil on a scale that rivals the earthworms, disperse the seeds of countless plants, prune and harvest the vegetation, and concentrate nutrients around their nests until they become, in Wilson's phrase, ecological engineers whose collective activity restructures the very landscapes they inhabit.
This ecological dominance is the direct dividend of sociality, and Wilson never let the reader forget the connection. It is precisely because these insects act collectively — because a colony can mass hundreds of foragers on a food source within minutes, can defend a rich nest site against all comers, can build and climate-control a structure no individual could make — that they have come to rule the insect world so thoroughly. Solitary insects, however numerous, cannot marshal such coordinated force. The colony can. The advantages of cooperation, once sociality had arisen, drove the social insects to their ecological triumph, and that triumph is the reason the puzzle of their evolution is not a small technical matter but a central question about how the living world came to be arranged as it is. The self-denying worker is the foundation on which the most successful insects on Earth are built.
If the division of labor is the defining achievement of insect societies, then the question of how a colony parcels out its work becomes the master problem of the field, and Wilson approached it with an economist's eye. He introduced into the study of insects an explicitly ergonomic view of the colony: the colony as a system that allocates its workers among competing tasks so as to maximize its overall productivity, and ultimately its output of new queens and males. This was an unusual framing for its time, and a revealing one. It reflected Wilson's lifelong drive to make natural history quantitative and predictive rather than merely descriptive — to move from cataloging what colonies do to modeling why they do it. Caste ratios, in this view, are not arbitrary facts of natural history. They are something closer to solutions: the proportions of nurses and foragers and soldiers that, given a species' way of life, yield the most successful colony. The colony became, in his hands, a problem in optimization, and the tools of economics became instruments of biology.
Caste itself, Wilson showed, is produced in more than one way, and the variety is deeply instructive, for it lays out something like an evolutionary sequence for the eye to read. In many bees, whether a genetically ordinary female larva grows into a queen or into a worker is settled not by its genes but by its nutrition and its developmental environment — caste as an environmentally regulated outcome, a switch thrown by circumstance rather than a fate written in the egg. In many social wasps, reproductive roles are not built into the body at all but are negotiated continuously among adult females through dominance interactions, contests of rank that determine who lays eggs and who labors. Here caste is behavioral and reversible, a matter of social standing rather than anatomy. In the ants and the termites, by contrast, caste is often locked irreversibly into the body's very form, with workers, soldiers, and reproductives following separate developmental tracks that produce separate physical types.
How a larva is steered onto one developmental track rather than another — how the colony builds the castes it needs — is a question Wilson pursued with particular care, because it is where the biology of the individual meets the organization of the whole. Caste determination, he showed, is a regulated developmental process, channeled by nutrition, by hormones, and by environmental cues acting during sensitive windows of a larva's growth. A female larva in a honeybee colony fed the rich diet of royal jelly becomes a queen; her sister, fed ordinarily, becomes a worker, though the two are genetically alike. In the ants, the quantity and quality of food a larva receives, the temperature at which it develops, even chemical signals from the queen and workers, tip it toward one caste or another. The colony, in effect, manufactures its workforce to specification, adjusting the proportions of its castes by regulating the development of its young — a colony-level control over individual development that is among the clearest expressions of the society's organismal integration.
Among the termites this morphological specialization reaches baroque extremes. Soldier castes appear equipped with defensive structures so exaggerated — enormous armored heads, mandibles like shears, nozzles that spray defensive chemicals — that the soldiers can no longer feed themselves and must be fed by others. Division of labor, carried to such a pitch, has made the individual not merely specialized but dependent, a component that functions only within the whole. Arranged side by side, from the plastic, negotiated castes of the wasps to the fixed and physically differentiated castes of the ants and termites, these cases sketch a plausible evolutionary progression: from flexible roles settled by behavior toward rigid roles settled by development, a gradual hardening of the division of labor as societies grow more advanced. Wilson read that progression across the living diversity of the social insects as one might read a sequence preserved in stone.
Even where the bodies within a caste are identical, a colony can still divide its labor — not across forms but across time. Wilson described the widespread pattern he called age polyethism, in which a single worker moves through a sequence of occupations as it ages. Typically it begins its adult life deep inside the nest, tending the queen and nursing the brood in the safest quarters, and graduates over the following weeks to work nearer the entrance, and at last to foraging in the dangerous world outside, where a worker is most likely to die. This temporal division of labor achieves specialization without requiring physically distinct castes: the same individual simply performs different work at different stages of a life that spends its safest early days on the colony's most precious cargo and its expendable later days on its most hazardous errands. There is an economy even in the sequence, the colony extracting the safe indoor labor of a worker's youth before risking it in the field.
And the allocation is never fixed. Colonies continually adjust the proportions of workers assigned to each task in response to disturbance, opportunity, and need — sealing a breach, mustering foragers to a windfall, shifting nurses to a sudden abundance of brood. This adaptive plasticity is not directed from above. It reveals a decentralized system of workforce regulation, in which colony-level responsiveness emerges from the local decisions of many individuals rather than from any central authority surveying the whole and issuing commands. For there is no such authority. This is perhaps the deepest of Wilson's insights into insect societies, and the one whose reach extends furthest beyond entomology. The queen, despite her name, commands nothing; she is an egg-laying organ, not a ruler. There is no overseer in the nest, no coordinator, no insect that holds a plan of the colony's needs. Order at the level of the colony emerges from the summed simple actions of many individuals, each responding only to the local cues immediately before it.
The point about the queen is worth dwelling on, for it overturns the intuition that a society must have a sovereign. In the popular imagination the queen governs, issues orders, directs the colony's affairs. She does none of these things. She is, functionally, the colony's ovary — an organ of reproduction, specialized so completely for egg-laying that in many species she cannot feed or groom herself and depends entirely on her workers. What influence she exerts over the colony's reproduction is chemical and largely inhibitory: in some species her pheromones suppress the development of the workers' ovaries, so that her presence, not her command, keeps the reproductive division of labor intact. Even this queen control has its limits, and the tensions it papers over — the latent reproductive interests of workers who are not, after all, perfectly identical in their genetic stakes — are among the frictions that a fuller account of colony life must acknowledge. The colony is a cooperative venture, but it is not a frictionless one, and Wilson was careful never to present it as a utopia of selfless harmony.
Wilson gave this phenomenon a name — mass action — and described how individually modest signals, each conveying almost nothing on its own, aggregate into colony-level information processing, into adaptive collective behavior with no collective decision-maker anywhere in the system. A single ant laying a chemical trail to food is following a rule of the utmost simplicity; ten thousand ants laying and following such trails produce a foraging system that discovers, exploits, and abandons food sources across a territory with an efficiency no individual could approach or comprehend. In this early articulation of what would later be called self-organization, the colony appears as a system that computes solutions to its problems through the combined small acts of its members. The intelligence is real — colonies solve genuine problems of logistics, defense, and construction — but it is distributed. It lives in the interactions, not in any insect. No ant is smart; the colony is.
What binds these decentralized actors into a single functioning entity is communication, and here Wilson wrote from the very center of his own research, for the decoding of insect communication was among his greatest scientific contributions. Insect colonies are coordinated overwhelmingly by chemistry. Chemical signals — pheromones — pass information from individual to individual: trails that lead to food, alarm substances that summon defenders and orient them toward a threat, recognition labels that mark an insect as friend or foe. The machinery of the superorganism, in other words, is largely chemical, a traffic of molecules through which thousands of separate bodies are made to act as one. Wilson would give this subject its own sustained treatment, and it receives a chapter of its own in this book; here it is enough to see that communication is the medium in which the colony's collective life is conducted, the invisible tissue connecting the parts. (The language of chemical communication is taken up in Chapter 3.)
One class of chemical signal deserves particular notice here, because it makes the colony possible as a bounded thing at all: the signals of recognition. A colony can function as a cooperative unit only if its members can reliably tell one another apart from outsiders, admitting kin and excluding intruders, parasites, and the social parasites that specialize in slipping past a colony's defenses. Wilson and Hölldobler traced how a colony comes to carry a distinctive shared odor — a chemical signature blended from genetics, diet, and the materials of the nest, and spread among all the members by constant contact, so that the colony smells, in effect, of itself. Young workers learn this signature and judge others against it. Here the superorganism reveals a kind of immune system, a means of maintaining its own integrity against a world of would-be exploiters, and it is no accident that the analogy to a body's defenses is so close. A whole must be able to distinguish itself from what is not itself; the colony odor is how the insect society draws that line.
The collective foraging of the social insects shows this distributed intelligence at its most impressive, and it drew from Wilson some of his most characteristic analysis. A colony faces a genuine problem of logistics: food is scattered unpredictably across a territory, it must be found, and once found it must be exploited quickly before competitors or the elements claim it. No ant holds a map or a plan. Yet the colony solves the problem through mass recruitment — a forager that finds food returns to the nest laying a chemical trail, and the nestmates it draws out lay trail in their turn if the food proves good, so that a rich source rapidly recruits a crowd while a poor one is quietly abandoned as its faint trail evaporates. The colony, through nothing more than many individuals following and reinforcing a simple rule, allocates its foragers across the landscape in rough proportion to the reward available, behaving as though it were optimizing its energetic yield. Wilson brought foraging theory, developed for whole organisms, to bear on this colony-level economy, treating the society as a single forager writ large.
The honeybees carry signal-based coordination to a height that has astonished observers since it was first decoded: the waggle dance, by which a returning forager communicates to her nestmates, through the angle and duration of a stylized run performed in the darkness of the hive, both the direction and the distance of a food source she has found. It is a symbolic communication system — a signal that stands for something remote in space — and it ranks among the most sophisticated known anywhere outside human language. Wilson treated it as a demonstration of just how far the signaling of a social insect can be elaborated when selection favors the swift, accurate sharing of information among the members of a colony. What a solitary insect has no use for, a society turns into the very sinew of its collective life.
The same collective capacities that make a colony a superb forager make it a formidable combatant, and Wilson did not romanticize the social insects into models of universal peace. Colonies war upon colonies, and here too numbers and coordination decide the outcome: larger colonies overwhelm smaller ones, and the tactics of mass attack and coordinated assault turn a society's collective strength against its rivals. The cooperation that binds a colony inward is matched by an implacability turned outward, toward other colonies and other species, and the recognition systems that admit a nestmate as kin are the same systems that mark an outsider for attack. The insect society is a cooperative whole precisely by being a bounded one, its internal harmony inseparable from the sharp line it draws at its own edge.
Having built the concept in the insects he knew best, Wilson could not resist testing how far it would reach. In Sociobiology: The New Synthesis (1975) he extended the analysis of social behavior — division of labor, cooperation, communication, conflict — outward across the whole of the animal kingdom, beginning at the humblest level with the colonial microorganisms and invertebrates in which cooperation and role-specialization already faintly appear, and proceeding upward through the fishes, birds, and mammals to the primates. The social principles he had worked out among ants and bees became, in this larger frame, particular instances of something general: the recurring tendency of life to assemble cooperative wholes out of competing parts, at level after level, wherever the advantages of cooperation come to outweigh its costs. That vast extension would carry him, controversially, all the way to our own species — but that part of the story, and the storm it raised, belongs to later chapters (see Chapter 6, Sociobiology, and Chapter 16, Human Evolution). What matters here is the intellectual move itself: the insect society had become a template for thinking about social life as such.
It is worth remembering that all of this began in observation — in a boy's and then a young man's patient watching of ants in the field, turning logs and following trails, the naturalist's work that Wilson never abandoned even as his ambitions grew theoretical. The synthesis of 1971 was possible because Wilson had first gathered, and then gathered together, the scattered findings of many specialists across many groups of insects into a single unified science of insect societies, positioning himself deliberately as the one who would join what had been studied piecemeal. The comparative program he announced — systematically setting the four great groups of social insects side by side, the ants, the social bees, the social wasps, and the termites, to reveal both their shared principles and their instructive differences — was the method of a naturalist raised to the level of a research strategy. The superorganism was not an armchair abstraction. It was distilled from a lifetime spent watching real colonies do the things that only colonies can do.
The comparison across the four groups yielded one of the most profound lessons of the whole science, which is that eusociality is not a single event but a repeated one. The ants, the social bees, the social wasps, and the termites did not inherit their sociality from a common social ancestor; each lineage crossed the threshold into true sociality independently, and the honeybees and the termites are as distantly related as an insect can be from another. That the same demanding combination of traits — cooperative brood care, overlapping generations, reproductive division of labor — arose again and again, by separate paths, tells us that the conditions favoring it must recur in nature, that there is something about the situation of certain insects that repeatedly makes the surrender of individual reproduction pay. And the differences among the groups are as instructive as the shared outcome. The termites, uniquely, are diploid like ourselves and social in both sexes, their workers and soldiers drawn from males and females alike, whereas in the ants, bees, and wasps the sterile castes are exclusively female, the males mere brief instruments of reproduction. That contrast alone, Wilson saw, forbids any single, tidy explanation of insect sociality and forces the naturalist to hold several forces in view at once — the genetic, the ecological, the developmental — as the true account of how these societies came to be.
In his more reflective books Wilson turned the superorganism to broadly philosophical use. In Biophilia (1984) he dwelt on the leafcutter ants — their subterranean fungus gardens, their elaborate caste systems, their assembly lines of workers graded by size for graded tasks — as a case study in how natural selection can build, from simple parts following local rules, an order of astonishing intricacy. The emergent order of the colony he presented as one of nature's most striking phenomena: properties belonging to the whole that reside in none of the parts, arising from the interactions among members rather than from any member itself. And he let the colony raise questions that reach far past entomology — questions about the individual and the whole it serves, about identity and sacrifice and the reconciling of the interests of parts with the interests of the wholes they compose. The colony became for him a way of thinking about one of the oldest problems in biology and in ethics alike: how the one and the many are to be squared. That theme returns, transformed, in his writing on human society and on the moral sense (see Chapter 22, Ethics & the Moral Sense).
The idea reached its mature and fully explicit form in The Superorganism (2009), written once more with Hölldobler, a book whose very title announced the arrival of what had for decades been an undercurrent. Here the analogy Wilson had carried quietly since 1971 was set out in the open and made to do real analytical work. The development of a colony — its sociogenesis, the process by which a founding queen's first few workers give rise, over months and years, to a mature and complex society — was placed deliberately alongside the development of an organism from a fertilized egg, its morphogenesis. The two were treated as comparable problems, governed by comparable logics of differentiation and regulation. The colony has a life cycle that invites the comparison directly: it is founded, it grows, it matures, it reproduces, and it dies, exactly as an organism is born, grows, matures, reproduces, and dies.
Wilson and Hölldobler divided that life cycle into three stages, and the division repays attention, for it is the organismal analogy made concrete. First comes the founding stage, when a single mated queen, having shed her wings, seals herself into a chamber and rears her first brood alone, drawing on her own body's reserves — a stage of extreme vulnerability, a bottleneck through which only a small fraction of queens survive. Then comes the ergonomic stage, in which the colony grows purely by adding workers and builds up its labor force and its stores, producing no reproductives at all, investing everything in growth — the insect equivalent of an organism's development toward maturity. Only when the colony reaches a sufficient size does it enter the reproductive stage and begin to produce the winged males and new queens that will fly out to found colonies of their own. Growth first, then reproduction: the colony, like the body, does not attempt to reproduce until it has grown up.
The founding stage repays a closer look, for it is where the colony's life is most precarious and where the logic of the whole enterprise is thrown into sharpest relief. When a young queen leaves her natal colony on her nuptial flight, mates, and descends to earth, she performs an act of startling finality: she breaks off her wings, never to fly again, and seals herself into a small chamber, cut off from the world. There, drawing solely on the reserves stored in her own body — including the now-useless flight muscles, which she metabolizes — she lays her first eggs and rears her first brood entirely alone, without the workers who will later do all such labor. It is a bottleneck through which only a tiny fraction of queens pass; the vast majority die, taken by predators, by rivals, by the elements, or by simple failure before that first cohort of workers matures. But once those first workers emerge and take up the tasks of foraging and nursing, the queen need never work again, and the colony's exponential growth begins. Wilson saw in this vulnerable, solitary founding the recapitulation of the colony's own evolutionary past — the queen, briefly, living the self-sufficient life of the solitary ancestor before the superorganism she is founding takes over and relieves her of everything but reproduction.
The brood — the eggs, larvae, and pupae on which so much of the colony's labor is lavished — are not incidental to this life cycle but are its very point, the colony's future taking shape in its most protected chambers. The care of the young, one recalls, was among the defining criteria of eusociality, and in a mature colony that care is unceasing: larvae are cleaned, fed, moved among chambers to keep them at the right temperature and humidity, and defended ahead of the adults themselves. In this the priorities of the superorganism show plainly. A colony will sacrifice its foragers, its oldest and most expendable members, before it risks its brood, in which its whole reproductive prospect is invested. The willingness of the individual worker to place the colony's future above its own survival — to rush toward a threat, to be spent in the field — is the behavioral face of the reproductive division of labor, and it is nowhere more visible than in the defense of the young.
The integration of the colony runs deeper than signaling; it extends to the sharing of food itself, and so to the colony's very metabolism. Through trophallaxis, the mouth-to-mouth exchange of liquid food among members, nourishment taken in by foragers is passed through the colony from individual to individual, distributed among workers, brood, and queen in a continuous internal circulation. The developing larvae are not merely passive recipients of this flow but participants in it, secreting substances that the adults consume, so that even the immature stages are woven into the collective economy of the society. Food, and with it chemical information about the colony's state, moves through the society as blood moves through a body, and the boundary between the nutrition of the individual and the nutrition of the whole all but dissolves. To watch a colony feed is to watch a single distributed digestive system at work, its members the organs of a shared metabolism.
In this circulation, too, the superorganism analogy proves more than a figure of speech. The colony takes in energy and materials from its environment, distributes them internally according to need, maintains its internal conditions against external change, grows, and in time reproduces — the whole repertoire of an organism's physiology, achieved not by organs of tissue but by the coordinated behavior of thousands of separate insects. Wilson's insistence on treating the colony as a unit was, in the end, an insistence that this functional unity is real and not merely apparent, that the colony does the things a living thing does, and that a biology which studied only the individual insect would miss the phenomenon that most needed explaining.
Around this life cycle the authors gathered the evidence that most compellingly justifies the superorganism concept: the phenomena of social homeostasis. A colony maintains stable internal conditions — regulating the temperature and humidity of its nest through coordinated behavior, relocating brood among chambers as conditions change, adjusting its workforce to keep the whole in balance — in a manner directly analogous to the physiological regulation by which an organism holds its internal state steady against a fluctuating world. The colony behaves, in short, as a homeostatic system, and homeostasis is one of the surest marks of an integrated living thing. Simple behavioral rules of thumb, followed by individual workers and compounded through what the authors called multiplier effects, generate at the colony level a regulation that no individual intends or perceives. The parts, each following its own small rules, produce a self-governing whole.
Nowhere is the colony's collective capacity more tangible than in what it builds. The nests of the social insects are among the most impressive structures made by any animals: the great mounds of certain termites, raised to heights many thousands of times the length of their builders and ventilated by a system of passages that regulates the flow of air and the escape of heat with a sophistication human engineers have studied for lessons. No termite holds the plan of the mound; the structure arises, like the colony's foraging and its division of labor, from many individuals following simple local rules, each responding to the work already done by others, so that the building guides its own construction. Wilson saw in such architecture the same principle that governed everything else about the insect society — complex, adaptive, colony-level order emerging without design from the summed simple acts of the many — and he saw, too, that a structure of this kind is best understood not as a thing the insects make but as a part of the superorganism itself, an external organ of the collective body, as much a product of the colony's coordinated life as a shell is the product of a mollusk's.
The superorganism concept also reframes the most vivid feats of insect cooperation as the coordinated action of a single entity. Wilson and Hölldobler described the weaver ants, whose workers form living chains of their own bodies to draw the edges of leaves together, while other workers hold larvae in their mandibles and gently squeeze them to extrude the silk that binds the leaves into a nest — the larvae pressed into service as living tools, the whole a feat of synchronized teamwork impossible for any solitary insect and difficult even to describe without the language of collective purpose. Such construction, like the great regulated mounds of the termites, represents a high grade of cooperation in which the individual all but disappears into the coordinated act. And when at last the queen dies, the colony dies with her, for the workers cannot perpetuate the society; the death of the reproductive individual is the death of the superorganism, the final term of the organismal analogy, birth answered by death.
What all these phenomena have in common — the fed soldier who cannot feed himself, the larva pressed into service as a source of silk, the forager spent in the field, the queen who cannot survive without her workers nor they reproduce without her — is a thoroughgoing interdependence, a mutual reliance so complete that the individual insect can no longer be understood as a self-sufficient organism at all. It has become a part. Just as a cell taken from a body dies, unable to live the independent life its distant ancestors led, so a worker ant removed from her colony is a fragment of a thing, not a whole thing, and does not long survive. This is the deepest sense in which the colony is a superorganism: not merely that it behaves like an organism, but that its members have become, over evolutionary time, something like the organism's parts, their independence traded away for the advantages of belonging to a greater whole. The insect society represents one of life's major transitions, one of those rare events in the history of life in which formerly independent units combined so thoroughly that a new and higher level of individuality was born.
One question Wilson raised at the very beginning he never fully put to rest, and it is a measure of his intellectual honesty that he kept reopening it rather than declaring it closed. If selection can favor arrangements that help the colony as a whole to survive and reproduce, how does that colony-level advantage relate to the older Darwinian accounting in terms of individuals and their genes? The most powerful answer developed during his career came from the theory of kin selection: because the sterile workers of ants, bees, and wasps are helping to rear close relatives — in the Hymenoptera, owing to their peculiar haplodiploid genetics, sometimes relatives more closely related to them than their own offspring would be — the genes for self-sacrificing labor can spread after all, carried forward in the bodies of the kin that the workers help to produce. Altruism, on this account, is not a defiance of Darwinism but an expression of it, once one learns to count genes rather than individuals.
Wilson used this framework, and yet he never let it settle into dogma, for he was too honest a naturalist to ignore the cases that strained it. The termites, he pointed out candidly, are as advanced in their sociality as any ant, and yet they are not haplodiploid; the neat genetic asymmetry that helps explain eusociality in the Hymenoptera simply does not apply to them, so that relatedness alone cannot be the whole story, and ecology, inbreeding, and the advantages of defending a valuable nest must be admitted alongside it. He weighed selection on individuals against selection on whole colonies in 1971, and the tension he identified there never left him. Decades later, to the consternation of many colleagues who regarded the matter as settled, it led him back toward a controversial re-embrace of group selection, a willingness to say that selection among colonies, and not only among genes, had shaped the social insects. The debate is properly the subject of a later chapter (see Chapter 5, The Evolution of Social Behavior). What belongs here is the recognition that the insect society was for Wilson never a settled curiosity but a living problem, one he was still turning over, and still revising his mind about, at the end of his life.
That, finally, is why the insect societies stand at the head of this book. They were the ground on which Wilson learned to see the world — not as a collection of isolated objects but as a hierarchy of levels, each with its own emergent order, each built from the level below by the patient, unplanned work of natural selection. The colony taught him that a whole can be genuinely more than, and different from, the sum of its parts; that coordination can arise without a coordinator; that the surrender of the individual to the collective can be, under the right conditions, the very thing that natural selection rewards. And it left him with a question he would spend the rest of his career carrying upward, from the ant nest to the human city and at last to the fate of the living planet: how far, and by what means, can the interests of the part and the interests of the whole be reconciled? The chapters that follow trace where that question led him — to the ants in their full variety, to the evolution of cooperation and its great controversy, to human nature itself, and at last to the living world in need of saving. But it begins here, in the nest, with the small and inexhaustible astonishment that separate creatures can become one.