If the insect societies gave Edward O. Wilson his great idea, it was one family of insects above all that gave him his life's work. He was, before he was anything else, a student of ants — a myrmecologist, in the term of the trade — and he remained one to the end, through all the controversies and syntheses and public battles that carried his name far beyond entomology. Ants were his first scientific love and his last; the small creatures underfoot were, for him, a lens through which the whole of biology could be brought into focus. This chapter is about the ants themselves: what they are, how astonishingly various they are, how they came to rule so much of the terrestrial world, and how one boy's fascination with them grew into the most authoritative body of knowledge any single naturalist has assembled about a group of animals.
To begin with the plainest fact about ants is already to begin with a wonder, for ants are, by several measures, among the most successful animals that have ever lived. Though small and easily overlooked, they run much of the terrestrial world. Wilson and his lifelong collaborator Bert Hölldobler opened their great treatise on ants by establishing exactly this: that ants, unnoticed as they mostly are, function as the soil-turners, the scavengers, the predators, and the earth-movers of nearly every land habitat outside the polar regions. In many places, and above all in the tropical forests, ants compose a startling fraction of the entire animal biomass — by some of the striking estimates Wilson and Hölldobler assembled, the ants and termites together may outweigh all the terrestrial vertebrates combined. The living weight of ants on Earth is a thing difficult to grasp and impossible, once grasped, to forget.
This dominance is not a matter of numbers alone but of ecological force. Ants move soil on a scale that rivals the earthworms, aerating and turning the earth as they excavate their nests. They disperse the seeds of countless plants, and concentrate nutrients in the middens and chambers around their colonies until the very chemistry of the soil is altered. They are, in the phrase Wilson and Hölldobler made current, ecological engineers, organisms whose collective activity restructures the physical world around them. And they are predators and scavengers on a massive scale, collectively removing an enormous tonnage of other insects and organic matter from the landscapes they patrol. To remove the ants from a tropical forest would not be to subtract a detail; it would be to pull out a load-bearing wall.
That such abundance can persist at all raises a question Wilson found deeply absorbing: how do so many kinds of ants manage to coexist, when all of them want more or less the same things? Competition among ant species, he and Hölldobler argued, is a primary force organizing ant communities, shaping which species can live together in a given place and which are excluded. They drew from the mass of field data a dominance-impoverishment rule, by which a few aggressive, competitively superior species can suppress the diversity of an entire community, monopolizing the richest resources and driving subordinate species to the margins. Yet coexistence is the rule in nature, not competitive exclusion, and so they examined with equal care the conditions that allow ecologically similar species to persist side by side — the partitioning of resources by size or season or microhabitat, the trade-offs by which a species dominant at one thing cedes another. In this attention to how competition and coexistence balance out across whole assemblages, the study of ants became a study of community ecology itself, the ant fauna of a place serving as a model for how nature packs many species into a shared world.
Behind this ecological weight lies an extraordinary diversity, and it was the diversity, as much as the dominance, that held Wilson through a lifetime of study. There are many thousands of ant species — the number known to science has climbed past twelve thousand and continues to rise with every expedition into an under-collected forest — and they range across an astonishing spread of body forms, sizes, diets, and ways of life. Wilson surveyed this range early, in The Insect Societies, establishing the ants as at once the most diverse and the most ecologically pervasive of the social insects, and he never stopped marveling at what he and Hölldobler would later simply call the endless variety of ant forms and habits. From ants smaller than the head of a pin to tropical giants, from blind subterranean hunters to sharp-eyed jumpers, from strict predators to devoted farmers, the family Formicidae contains a range of adaptation that a naturalist could spend several lifetimes cataloging and still not exhaust.
To bring order to this profusion is the task of taxonomy, and here Wilson was a master of the old, exacting discipline of the systematist. He and Hölldobler surveyed the anatomical characters — the segments of the antennae, the structure of the waist, the armament of the mandibles — by which the ant taxa are distinguished, and provided the keys and diagrams by which a specimen in hand can be assigned its name. This is unglamorous work, the careful comparison of tiny structures under a microscope, but it is the indispensable foundation of everything else, for one cannot study what one cannot first tell apart. Wilson situated the ants phylogenetically among the Hymenoptera, the great order that also holds the bees and wasps, and traced their evolutionary origin back to wasp-like ancestors many tens of millions of years in the past, from which the whole radiation of modern ants descends.
To understand an ant is first to understand that one is rarely looking at an individual in any ordinary sense, but at a member of a colony that is almost entirely female and organized wholly around the welfare of its queen. The ant colony, Wilson and Hölldobler emphasized, is a queen-centered society: a single long-lived reproductive female, or sometimes several, surrounded by her sterile daughters, the workers, who carry out every task of the colony's life except reproduction itself. The queen is no ruler — that popular error is corrected at length in the treatment of the insect societies in the previous chapter — but she is the reproductive heart of the society, and her prodigious, sustained egg-laying, continuing in some species for a decade or more, is what sustains the colony across time. The males, by contrast, are ephemeral, produced in season for the single purpose of mating and dying soon after, a striking asymmetry that lies at the root of much of ant social biology.
How a new colony comes into being is one of the great dramas of ant natural history, and Wilson returned to it often. It begins with the nuptial flight, the dangerous aerial mating in which winged queens and males leave their nests, often in vast synchronized swarms timed to weather and season, and mate on the wing or shortly after landing. For the male it is a one-way journey ending in death; for the queen it is the beginning of everything, if she survives — and the great majority do not, falling to birds, to other predators, or to simple misfortune before they can establish themselves. A surviving queen sheds her wings, never to fly again, and founds her colony, most often by the mode called independent claustral founding: she seals herself into a chamber and rears her first brood entirely alone, drawing on the metabolized reserves of her own body, including her now-useless flight muscles, until the first workers emerge to take up the colony's labor. Wilson and Hölldobler catalogued the variations on this theme with a taxonomist's precision, distinguishing colonies founded by a single queen from those founded jointly by several, and describing how such jointly founding queens are often later reduced to one through eviction or outright execution once the first workers arrive.
Within the worker force itself, many ant species elaborate a further division, dividing labor not only by age but by body form, in a physical polymorphism that Wilson analyzed with particular care because it bears so directly on the ergonomic logic of the colony. In such species the workers are not uniform but come in graded sizes and shapes — small-headed minors that tend the brood and do the delicate indoor work, large-headed majors, often called soldiers, whose powerful mandibles serve in defense or in the milling of hard seeds. Wilson devoted some of his most influential early research to the mathematics of this caste system, to the question of what mix of minors and majors yields the most productive colony, and to how a colony adjusts the proportions of its castes to its needs. The distinction he drew among caste, task, and role — the physical type an ant is born into, the job it happens to be doing, the part it plays in the colony's economy — became standard conceptual currency in the field, a way of thinking clearly about how the labor of a society is partitioned among its members.
The nests in which all this life unfolds are themselves a study in diversity, and Wilson catalogued their range with evident pleasure. Ants nest in the soil and in rotting wood, under stones and in the hollow thorns and stems of plants, in the canopy of rainforests and in the walls of houses, from simple burrows to elaborate arboreal constructions and the vast subterranean cities of the leafcutters. The nest is not merely a shelter but, as Wilson stressed, a habitat in its own right, a stable and resource-rich microcosm that a whole community of other creatures has evolved to exploit — beetles, mites, and other arthropods that live as tolerated guests, as scavengers, or as cunning parasites and thieves within the colony's walls, mimicking its odors and stealing its food or its brood. To open an ant nest, Wilson knew, is to open a small world.
Some living ants offer a window onto that deep ancestry, and Wilson pursued them with particular relish. Certain anatomically primitive genera — Amblyopone, the fierce Australian bulldog ants of the genus Myrmecia, and above all the celebrated Nothomyrmecia — retain ancestral traits that hint at what the earliest ants may have been like, bridges to the wasp-like founders of the line. The rediscovery of Nothomyrmecia, the most primitive living ant, was one of the small epics of twentieth-century entomology, achieved after decades of searching in remote Australia, and Wilson and Hölldobler recounted it with the excitement of naturalists who understood exactly what such a living relic could teach. From humble and obscure beginnings, they showed, the ants radiated over geological time into the thousands of species alive today, a great evolutionary success story written across the Cenozoic.
The story of that radiation is one Wilson helped to write in more than one sense, for he contributed to the understanding of ant origins not only through living species but through the fossil record, including the discovery and interpretation of ants preserved in amber from the age of the dinosaurs. From forms close to the wasp-like ancestor, the ants diversified through the long ages of the Cenozoic into the thousands of species that populate the modern world, spreading into nearly every terrestrial habitat and evolving the whole spectrum of ways of life that Wilson spent his career documenting. He connected this deep-time origin story to the ants' present dominance, showing how an ancient and initially modest lineage came, through the compounding advantages of social life, to its current position as one of the ruling groups of the terrestrial biosphere. The rise of the ants was, in his telling, a slow revolution, its consequences still unfolding across every continent but Antarctica.
Among the countless forms this radiation produced, a handful of ways of life stand out as the great set pieces of ant natural history, and Wilson returned to them again and again, for they display the powers of the ant colony at their most spectacular. The first of these is the way of the army ants — the marauding legions, in the phrase Wilson and Hölldobler gave them. Army ants are defined not by their descent but by a distinctive syndrome of behavior: a nomadic life without a fixed nest, group predation, and mass raiding. Rather than send out scouts to find food and recruit to it, the army ants simply advance, hundreds of thousands of workers sweeping forward in a coordinated front across the forest floor, overwhelming and dismembering whatever prey cannot flee before them.
The details of the army-ant life are among the strangest in the animal kingdom. Lacking a permanent nest, the colony forms its shelter from its own bodies, the workers linking leg to leg to build a living bivouac around the queen and brood, and throwing living bridges of their own linked bodies across gaps in the terrain — an architecture, as Wilson put it, made of the animals themselves. This living construction is another face of the self-organization that runs through all the social insects, the colony solving the problem of shelter with no material but itself. And the ecological effect of these nomadic predators is profound: army ants function as keystone species and as a genuine force of nature, major predators whose raids shape the abundance of countless other forest animals, and whose swarms carry with them a whole travelling community of associated creatures, birds and insects that follow the raid to feed on what it flushes.
The army ants stand at one extreme of a spectrum of predatory strategies that Wilson and Hölldobler surveyed across the whole family, from generalist hunters that will take almost any prey they can subdue to extreme specialists honed to a single quarry. Some ants hunt springtails with trap-jaws that snap shut faster than almost any movement in the animal kingdom; others specialize on the eggs of particular insects, or on other ants, or on prey of a single kind. This diversity of predatory strategy is itself a measure of the ants' evolutionary inventiveness, the family having radiated to fill nearly every conceivable predatory niche on the forest floor and in the soil and canopy above it. Taken together with their roles as scavengers, seed-harvesters, fungus-farmers, and herders of honeydew-producers, the ants' modes of feeding span very nearly the whole range of ways an animal can make a living, which is a large part of why they are so ubiquitous and so ecologically weighty.
If the army ants are the great hunters, the leafcutters are the great farmers, and Wilson regarded them as perhaps the supreme achievement of social evolution below humanity. The leafcutter ants of the American tropics do not eat the vegetation they so industriously harvest; they carry it underground to nourish gardens of fungus, which they cultivate as their sole food in one of the most remarkable agricultural symbioses on Earth. Their colonies, numbering in the millions, function like factories, with assembly lines of workers graded by size to graded tasks — the largest cutting and carrying leaf fragments, the smallest tending the delicate fungal threads — in a division of labor of astonishing precision. Wilson used the leafcutters, as he used few other animals, as the supreme concrete example of the superorganism: a society so integrated, so specialized, so productive that it functions as a single farming enterprise, an agricultural civilization in miniature that preceded human agriculture by tens of millions of years.
If the leafcutters farm, the harvester ants reap, and Wilson and Hölldobler devoted careful study to these gatherers of seeds, whose way of life is concentrated in the deserts and other dry lands where seeds are an abundant and durable resource. Harvester ants collect and store seeds as their principal food, and in doing so they become significant players in the ecology of the plant communities around them, selecting among available seeds by size, nutritional value, and the labor of handling, and organizing their collection along trunk trails that structure the foraging of the whole colony across its territory. Some species have become extreme specialists, evolved in body and behavior for a life built almost wholly on seeds. And because seeds are a resource many creatures covet, the harvesters compete not only among themselves but with birds and desert rodents for the same harvest, so that the study of granivory opens onto the larger question of how species divide a shared and limited resource among themselves.
The leafcutters are only the most famous of the ants' many partnerships with other organisms, for the ants are, in Wilson and Hölldobler's phrase, the farmers and herders of the insect world. Many ants tend sap-feeding insects — aphids and their relatives — as human herders tend cattle, protecting them from predators and harvesting the sugary honeydew they excrete, a relationship called trophobiosis. Others live in intimate partnership with plants, which provide them with hollow chambers, called domatia, and nutritious secretions in exchange for protection against herbivores and encroaching vegetation, a mutualism known as myrmecophily. The ant nest itself becomes a habitat, a rich and stable microcosm exploited by a whole guild of other arthropods that have evolved to live as guests, and sometimes as thieves, within it. Wherever one looks closely at an ant colony, one finds it embedded in a web of relationships with other species, giving and taking across the boundaries of the superorganism.
These partnerships repay a closer look, for they show how thoroughly the ants have woven themselves into the fabric of terrestrial life. In trophobiosis, the herding of sap-feeding insects, ants stroke aphids and scale insects with their antennae to induce them to release droplets of honeydew, and in return guard their living herds against predators and parasites, even carrying them to fresh feeding sites and sheltering them in the nest — a mutualism so developed that some aphids have come to depend on their ant tenders entirely. In myrmecophily, the partnership with plants, the exchange is architectural and nutritional: the plant grows hollow structures that house an ant colony and secretes food bodies to feed it, and the ants in turn patrol the plant, attacking herbivores and pruning away competing vegetation, so that plant and ant prosper together in a bargain struck over evolutionary time. Wilson catalogued these relationships as expressions of a general truth about the ants: that their ecological dominance is achieved not in isolation but through a dense network of alliances and exploitations binding them to plants, to other insects, and to the whole community of life around them.
Underlying all of this collective achievement — the raids and the farming, the warfare and the herding, the building and the harvesting — is the chemical language by which ants coordinate their societies, and it was in the decoding of that language that Wilson made some of his most consequential scientific discoveries. Ants are creatures of scent, communicating chiefly through pheromones: the trail substances that guide nestmates to food and enable the mass recruitment on which ant foraging depends, the alarm signals that summon and orient defenders, the colony odors by which an ant knows its own kin from an intruder. Wilson himself worked out the classification of these chemical signals by their function and identified the glandular sources of several, laying foundations on which the field still builds. The full account of that chemical language belongs to its own chapter (see Chapter 3, Chemical Communication); what matters here is that it is the very medium of ant sociality, the invisible chemistry that makes the visible empire of the ants possible at all.
Not all these relationships are benign, and Wilson was fascinated by the darker specializations of ant life no less than by the cooperative ones. Some ants are slave-makers — the dulotic species, which raid the colonies of other ants to carry off their brood, the captured young maturing to labor for their captors, who in the most extreme cases have lost the ability to feed themselves and depend entirely on their stolen workforce. Others are social parasites, exploiting the social systems of other ant species from within, sometimes described as practicing the ultimate form of parasitism, the theft not of a body but of a society. In these grim specializations Wilson saw the same evolutionary logic that produced cooperation turned to exploitation, the machinery of the colony hijacked by species that had evolved to break into it. The ant world, he made clear, is no utopia; it is a world of competition, territory, warfare, and slavery as much as of cooperation, and it is the more fascinating for being so.
Among the peaks of ant achievement Wilson placed the weaver ants, whose nest-building displays a grade of cooperation that approaches the miraculous. To build their arboreal nests, weaver ants must bind living leaves together, and they accomplish this through a feat of coordinated teamwork: rows of workers grip the edge of one leaf and strain to draw it toward another, sometimes forming living chains of their own bodies to span the distance, while other workers take up the colony's own larvae and gently squeeze them to extrude the silk with which the leaves are bound. The larvae, in effect, are used as living tools, their silk — which they would otherwise spin for their own cocoons — commandeered for the colony's construction. Wilson and Hölldobler analyzed this behavior as one of the highest grades of cooperation known among the ants, and reflected on the uncertain evolutionary climb by which such exquisitely coordinated behavior might have arisen, candidly acknowledging the gaps in any reconstruction of how it came to be.
For all their cooperation within the colony, ants are among the most warlike of animals in their dealings between colonies, and Wilson did not soften the picture. Warfare among ant colonies is frequent and often brutal, fought over food, over territory, and over nest sites, and its outcomes turn, as in human war, on numbers and organization — larger colonies overwhelming smaller ones, mass attacks and coordinated assaults deciding the fate of societies. Some species practice territoriality on a grand scale, patrolling and defending fixed boundaries; others raid, exploit, and enslave. The same recognition systems that bind a colony together by marking its members as kin serve equally to mark outsiders for attack, so that the cohesion of the ant society is inseparable from its hostility to other societies of its kind. Wilson saw in this no cause for either dismay or celebration, but simply the working out, at the level of the colony, of the competition that pervades all of life.
Behind all these discoveries stood a particular human life, and no account of Wilson's ants would be honest that did not tell how a Southern boy became the world's foremost student of them. The story, which Wilson told with great charm in his memoir Naturalist, turns partly on an accident of the body. A childhood injury left him with impaired distance vision but exceptionally sharp sight at close range, and he came to see this not as a handicap but as a strange gift, an eye almost designed for the examination of tiny organisms held close. The small creatures underfoot, and ants above all, were perfectly suited to his sharpened near vision, and he described the convergence of his damaged eyes and his boyhood curiosity as the quiet accident that pointed him toward his life's subject.
That subject took hold early and never let go. As a boy and then a student in Alabama, Wilson began serious fieldwork on ants, including an early study of the imported fire ant, then spreading northward through the American South — one of his first genuine scientific contributions, undertaken while he was still very young. He recounted his transformation into a dedicated hunter of ants, pursuing them across the landscape with a collector's zeal, and reflected that his deep knowledge of the group came not through passive study but through active pursuit, the hunt itself a way of knowing. He learned the discipline of the collector, the methodical, painstaking labor of finding, gathering, and preserving specimens, and he mastered the systematic knowledge of regional faunas — learning the ants of a place so thoroughly that their patterns of distribution began to speak to him of larger questions.
The imported fire ant, which Wilson studied as a young man as it advanced through Alabama, would prove a fitting first subject, for it displayed in miniature much of what would fascinate him for the rest of his life: the drama of an aggressive, superbly organized species spreading into new territory, reshaping the communities it entered, provoking and defeating human efforts to control it. It was a lesson, delivered early, in the ecological power of ants — in how a single well-adapted social insect, arriving where it had not been before, could remake a landscape and defy a nation's attempts to be rid of it. Wilson would carry the memory of the fire ant through a career that ranged to the far side of the world and back, and would return to the ants of his boyhood South, with unmistakable affection, in the tales he gathered near the end of his life.
The fire ant also pointed toward a phenomenon of growing importance in Wilson's lifetime and beyond it: the rise of the invasive ant, the aggressive tramp species carried by human commerce far beyond its native range, there to overrun the resident fauna and remake whole communities. A handful of such species — the imported fire ant among them — have become, in effect, ecological wrecking crews, their success abroad built on the same traits that make ants formidable everywhere: dense, cooperative colonies, aggressive competition, rapid reproduction, and in some cases the formation of vast interconnected supercolonies that dispense with the usual boundaries between nests. Wilson recognized in these invaders both a scientific problem of great interest and a conservation threat of real gravity, for where they establish themselves they can drive native ants and other animals toward local extinction, impoverishing the very diversity he prized. The connection between the fate of ant diversity and the broader crisis of biodiversity was one he drew explicitly, noting that the loss of ants would ripple destructively through the ecosystems they do so much to sustain — a theme that opens onto the conservation concerns of his later career (see Chapter 12, Nature Conservation & the Fight for Life).
For the ants led Wilson outward, from natural history toward theory, in a way that shaped his whole career. His great expeditions through the islands of the South Pacific, collecting ants across Melanesia and New Guinea and beyond, were undertaken in the systematist's spirit of documenting a fauna, but they set him puzzling over why the islands held the particular numbers and kinds of species they did. Studying how the composition of the ant fauna changed from island to island, and how species turned over along the mountain slopes as elevation climbed, he found himself moving from cataloging what was there toward asking what governed it. The ants of the Pacific islands became, in this way, the seedbed of the equilibrium theory of island biogeography, the great quantitative idea he would develop with Robert MacArthur — a story that belongs to a later chapter (see Chapter 9, The Theory of Island Biogeography), but that began here, on his knees in the field, following ants.
Those Pacific years were, in the most literal sense, the making of Wilson as a scientist, and they left him with a mastery of a great and difficult fauna that few naturalists of any era have equaled. Collecting across Melanesia, New Guinea, and the scattered archipelagoes of the South Pacific, he learned the ant fauna of a vast region island by island, building the comprehensive, specimen-by-specimen knowledge on which all sound taxonomy rests. He studied how the composition of the fauna shifted from one island to the next, and how, on the mountain slopes such as those of Mexico's Orizaba, the species turned over with elevation, each zone holding its own characteristic assemblage. This was the systematist's labor at its most demanding — the learning of hundreds of species, the discernment of the fine characters that separate them, the patient mapping of where each occurs — and Wilson embraced it fully, even as it began to raise in his mind the larger, quantitative questions that would carry him toward theory.
The montane gradients were especially telling, and Wilson lingered over them. Ascending a tropical mountain such as Orizaba, he found the ant fauna changing zone by zone with elevation, warm-adapted lowland species giving way to hardier montane ones, the whole assemblage turning over as the climate cooled with height. Such gradients were natural experiments in how environment shapes the distribution of species, compressing into a single mountainside the kind of faunal turnover that elsewhere plays out across great stretches of latitude. To read a mountain's ants from base to summit was to watch ecology and biogeography at work in miniature, and observations of just this kind were sharpening in Wilson the questions about distribution, immigration, and the balance of species numbers that would soon crystallize into theory. The particular, once again, was leading him toward the general; the ants he gathered on a Mexican slope were quietly posing the problems he would spend the next decade learning to solve.
Out of such fieldwork came, too, a conception of the naturalist's vocation that Wilson would defend all his life. He came to believe that real knowledge of a group of organisms is earned through active pursuit rather than passive study — that the hunt itself, the disciplined chase across difficult terrain, is a way of knowing not available to the armchair. The collector's discipline, the methodical gathering and careful preservation of specimens, he presented not as drudgery but as the foundation of the whole enterprise, the concrete labor on which every generalization ultimately rests. In an age increasingly enamored of laboratory and equation, Wilson stood as a champion of the field, insisting that biology must keep faith with the actual living organism in its actual place, and that the naturalist who truly knows a fauna possesses something no purely theoretical training can supply.
It was in this passage from the particular to the general that Wilson's cast of mind revealed itself. He had been trained as a descriptive naturalist, a namer and classifier of species, and he never abandoned or disparaged that work; but he came to feel that natural history should aspire to more, that it could and should become quantitative and predictive rather than merely descriptive. The ants, which he knew more intimately than anyone, were his proving ground for this conviction. In The Ants, the encyclopedic treatise he and Hölldobler published in 1990 — a book so comprehensive it would win them a Pulitzer Prize — they framed their aim as nothing less than the reorganization of myrmecology around general biological principles: not merely to celebrate the ants, though the celebration is everywhere evident, but to make the study of ants a science of laws as well as of species. The dominance-impoverishment rule, by which a few strong competitors can suppress the diversity of a whole community; the relation of colony structure to patterns of species distribution; the application of equilibrium concepts to how many species a habitat can hold — these were the generalizations Wilson sought to lift out of the mass of ant particulars.
The ambition behind that great book is worth pausing on, because it captures something essential about Wilson's mind. Myrmecology before him had been, in large part, a descriptive science, a vast accumulation of observations about particular species; Wilson wanted to lift from that accumulation the general principles that would make it a predictive science, one that could say not merely what a given ant does but why ants in general do what they do. The reorganization of the field around such principles — around the economics of the colony, the rules of competition and coexistence, the equilibrium of species numbers, the evolutionary logic of caste and cooperation — was the animating purpose of his ant work, and it is why his influence reached so far beyond the specialists. He made the ants a model system for biology at large, a group in which the deepest questions about social evolution, ecology, and the organization of life could be posed with unusual clarity, because the ants were at once so various, so tractable, and so thoroughly known. In doing so he transformed the study of a single insect family into a window on the living world entire.
That great book also carried, in its final pages, an unexpectedly practical spirit that reveals much about the man. Having filled hundreds of pages with theory and phylogeny and physiology, Wilson and Hölldobler closed with a working guide to the craft itself: how to collect ants in the field, how to sample different species and habitats, how to prepare specimens for the museum, how to culture living colonies in the laboratory and move them from field to bench without harm. It is the gesture of naturalists who have not forgotten that all the theory rests, in the end, on the patient hands-on labor of people willing to get down in the dirt and find the animals. Wilson never lost his respect for that labor, or his conviction that knowledge of the living world is earned through direct, disciplined contact with it.
That conviction had a practical corollary that Wilson was happy to spell out: if ants are to be understood, they must be kept, watched, and coaxed into revealing their lives, and he took evident pleasure in the craft of doing so. He and Hölldobler described how to breed new colonies in the laboratory, how to manage the delicate business of mating and founding under artificial conditions, how to transport whole colonies from field to bench without destroying them, and how to construct nests of plaster and glass in which the hidden subterranean life of an ant society could be brought up into the light and observed directly. Much of what is known about ant behavior was won in exactly this way, by patient observers watching captive colonies day after day, and Wilson honored that patient watching as the true engine of discovery. The great generalizations of his theoretical work were never far, in his own mind, from the glass-topped nest and the careful eye — from the unglamorous, absorbing labor of simply looking at ants until they gave up their secrets.
There is, running through all of Wilson's writing on ants, a note that is not quite scientific and not quite sentimental but something of both — a naturalist's joy, an unforced delight in the creatures themselves. It sounds in his celebration of the endless variety of ant forms, in the excitement with which he and Hölldobler recount the hunt for a primitive species in the Australian bush, in the affection with which, late in life and in a more personal key, he gathered his tales from a lifetime among the ants. That delight is not incidental to the science; it is, one comes to feel, its source. Wilson studied ants so well because he loved them first, and the love kept the science honest, tethered always to the actual living animal rather than to the abstraction. He wanted to know ants as they are, in all their diversity and strangeness, and he made it his business to find out.
And so the ants are, in this book, both a subject in their own right and a gateway to everything else. They were where Wilson learned to see, where he honed the systematist's patience and the theorist's ambition, where he first confronted the great puzzle of cooperation that would occupy him to the end. The mechanisms of their social life — the caste systems, the chemical communication, the superorganismic integration — are treated more fully elsewhere in these pages (see Chapter 1, The Insect Societies, and Chapter 3, Chemical Communication), for those are principles the ants share with the other social insects. What belongs to the ants alone is their sheer, overwhelming reality: the twelve thousand species and counting, the tropical forests heavy with their biomass, the raiding legions and the fungus farmers and the slave-makers and the weavers, the whole teeming empire of small lives that Wilson spent a lifetime learning to read. He once suggested that if he had his life to live over, he would happily spend it all on ants, and the reader of his work cannot doubt it. They were, for him, world enough.
To follow Wilson into the ant world is finally to receive a lesson in how much lies hidden in the overlooked. The ants are everywhere — underfoot in the garden, in the cracks of the pavement, in the walls of the house — and almost everyone passes them by. Wilson did not pass them by. He knelt down, and looked closely, and kept looking for the better part of a century, and out of that sustained attention came not only a mountain of particular knowledge but a whole way of understanding life: as a hierarchy of cooperation, built by natural selection, running from the gene to the colony to the ecosystem and beyond. The empire of the ants, patient and vast and mostly invisible, was the ground on which one of the great scientific imaginations of the age was formed. It is fitting that they stand near the beginning of this reader, for they stood at the beginning of Wilson.