SCIENCE; THE GENESIS OF A; GREAT NATURALIST

In his memoirs, Edward O Wilson reveals how childhood wonder led to research that changed the way we view society

EDWARD O Wilson, "the father of biodiversity", led a quietly absorbed life as a biologist until 1975. Then, the publication of his book Sociobiology triggered a political storm. At a meeting held in Washington in 1977, he was mobbed by demonstrators who poured a jug of water over his head and chanted: "Wilson, you're all wet!" It was the only instance in recent American history of a scientist being physically attacked for the expression of an idea.

In his autobiography Naturalist, extracted below, Wilson explains how his new discipline - sociobiology - had been featured on the cover of Time two months before his drenching. Earlier, he had received the National Medal of Science from President Carter. What changed his public reputation was a controversial chapter in Sociobiology in which he argued that some forms of human social behaviour were genetically influenced - a heresy in the 1970s. If human nature were rooted in heredity, some aspects of it were probably intractable - or could be declared so by a ruling elite. Tribalism and gender differences might be judged unavoidable, and war "natural"; ability and emotional attributes might be deemed fixed, beyond the reach of education and social policy. Wilson was branded a racist and a sexist, and was even accused of Nazi-style eugenics.

It is this controversial period of science history that is documented in Naturalist, the memoir chosen by the New York Times as one of its top 10 books of 1994. It begins with Wilson's childhood in Florida, where the beauty and diversity of the marine life sparked a passion for nature. Other chapters tell of his work as a Harvard professor in the 1950s, his receipt of the Pulitzer prize in 1979 for his book On Human Nature, and his efforts after that to expand and qualify his controversial ideas about heredity into a more coherent - and palatable - theory.

At the core of Wilson's career was his pioneering work with ants. It was this that led to his second Pulitzer, awarded in 1991 for his epic work The Ants. In their industrious colonies he saw the mark of evolution: soldier ants developed different physical characteristics to those of other ants, for example, as if "designed" for their combative role. The numbers of each seemed carefully balanced, as if to ensure the survival of the colony as a whole. The extract below explains the significance of Wilson's experiments with these insects, and how they led to his controversial ideas about sociobiology. We begin, however, with the day in Wilson's early childhood when a great naturalist was formed. Andrew Purvis

WHAT happened, what we think happened in distant memory, is built around a small collection of dominating images. In one of my own from the age of seven, I stand in the shallows off Paradise Beach on the east shore of Florida's Perdido Bay, staring down at a huge jellyfish in water so still and clear that its every detail is revealed as if it were trapped in glass. The creature is astonishing. I study it from every angle I can manage from above the water's surface. Its opalescent pink bell is divided by thin red lines that radiate from centre to circular edge. A wall of tentacles falls from the rim to surround and partially veil a feeding tube and other organs, which fold in and out like the fabric of a drawn curtain. I can see only a little way into this lower tissue mass. I want to know more but am afraid to wade in deeper and look more closely into the heart of the creature.

The jellyfish, I know now, was a sea nettle, formal scientific name Chrysaora quinquecirrha, a scyphozoan, a medusa, a member of the pelagic fauna that drifted in from the Gulf of Mexico and paused in the place where I found it. I had no idea then of these names from the lexicon of zoology. The only word I had heard was jellyfish. But what a spectacle my animal was, and how inadequate, how demeaning, the bastard word used to label it. I should have been able to whisper its true name: scyph-o-zo-an! Think of it! I have found a scyphozoan. The name would have been a more fitting monument to this discovery.

The creature hung there motionless for hours. As evening approached and the time came for me to leave, its tangled undermass appeared to stretch deeper into the darkening water. Was this, I wondered, an animal or a collection of animals? Today I can say that it was a single animal. And that another outwardly similar animal found in the same waters, the Portuguese Man-of-war, is a colony of animals so tightly joined as to form one smoothly functioning superorganism. Such are the general facts I recite easily now, but this sea nettle was special. It came into my world abruptly, from I knew not where, radiating what I cannot put into words except - alien purpose and dark happenings in the kingdom of deep water. The scyphozoan still embodies, when I summon its image, all the mystery and tensed malignity of the sea.

Paradise Beach was paradise truly named for a little boy. Each morning after breakfast I left the small shorefront house to wander alone in search of treasures along the strand. I waded in and out of the dependably warm surf and scrounged for anything I could find in the drift. Sometimes I just sat on a rise to scan the open water. Back for lunch, out again, back for dinner, out once again, and, finally, off to bed to relive my continuing adventure briefly before falling asleep.

It was the animals of that place that cast a lasting spell. I was seven years old, and every species, large and small, was a wonder to be examined, thought about and, if possible, captured and examined again. There were needlefish, foot-long green torpedoes with slender beaks, cruising the water just beneath the surface. Nervous in temperament, they kept you in sight and never let you come close enough to reach out a hand and catch them. I wondered where they went at night, but never found out. Blue crabs with skin-piercing claws scuttled close to shore at dusk. Easily caught in long-handled nets, they were boiled and cracked open and eaten straight or added to gumbo, the spicy seafood stew of the Gulf coast. Sea trout and other fish worked the deeper water out to the nearby eelgrass flats, and perhaps beyond; if you had a boat, you could cast for them with bait and spinners. Stringrays, carrying threatening lances of bone flat along their muscular tails, buried themselves in the bottom sand of hip-deep water in the daytime, and moved close to the surf as darkness fell.

How I longed to discover animals each larger than the last, until finally I caught a glimpse of some true giant! I knew there were large animals out there in deep water. Occasionally a school of bottlenose porpoises passed offshore less than a stone's throw from where I stood. In pairs, trios, and quarters they cut the surface with their backs and dorsal fins, arced down and out of sight, and broke the water again 10 or 20 yards farther on. Their repetitions were so rhythmic that I could pick the spot where they would appear next. On calm days I sometimes scanned the glassy surface of Perdido Bay for hours at a time in the hope of spotting something huge and monstrous as it rose to the surface. I wanted at least to see a shark, to watch the fabled dorsal fin thrust proud out of the water - knowing it would look a lot like a porpoise at a distance, but would surface and sound at irregular intervals. I also hoped for more than sharks, what exactly I could not say: something to enchant the rest of my life.

Why do I tell you this little boy's story of medusas, rays, and imagined sea monsters, 60 years after the fact? Because it illustrates, I think, how a naturalist is created. A child comes to the edge of deep water with a mind prepared for wonder. He is like a primitive adult of long ago, an acquisitive early Homo arriving at the shore of Lake Malawi, say, or the Mozambique Channel. The experience must have been repeated countless times over thousands of generations, and it was richly rewarded.

The sea, the lakes, and the broad rivers served as sources of food and barriers against enemies. No petty boundaries could split their flat expanse. They could not be burned or eroded into sterile gullies. They were impervious, it seemed, to change of any kind. The waterland was always there, timeless, invulner-able, mostly beyond reach, and inexhaustible. The child is ready to grasp this archetype, to explore and learn, but he has few words to describe his guiding emotions. Instead he is given a compelling image that will serve in later life as a talisman, transmitting a powerful energy that directs the growth of experience and knowledge. He will add complicated details and context from his culture as he grows older. But the core image stays intact. When an adult, he will find it curious, if he is at all reflective, that he has the urge to travel all day to fish or to watch sunsets on the ocean horizon. Hands-on experience such as I had at Paradise Beach, not systematic knowledge, is what counts in the making of a naturalist.

FOR 50 million years, ants have been overwhelmingly dominant everywhere on the land outside the polar and alpine ice fields. They are everywhere, dark and ruddy specks that zigzag across the ground and down holes, milligram- weight inhabitants of an alien civilisation who hide their daily rounds from our eyes.

By my estimate, between one and 10 million billion individuals are alive at any moment, all of them together weighing, to the nearest order of magnitude, as much as the totality of human beings. But a vital difference is concealed in this equivalence. While ants exist in just the right numbers for the rest of the living world, humans have become too numerous. If we were to vanish today, the land environment would return to the fertile balance that existed before the human population explosion. Only a dozen or so species, among which are the crab louse and a mite that lives in the oil glands of our foreheads, depend on us entirely. But if ants were to disappear, tens of thousands of plant and animal species would perish, simplifying and weakening land ecosystems everywhere.

From the earliest days, I placed ants at the centre of my professional life. They were the focus of a near obsession, and I think I chose wisely. Yet I confess that, at the time, their main appeal was not their environmental importance or the drama of their social evolution. It came from the discoveries they generously offered me. I built my career from easy revelation. The most important topic I addressed was their means of communication, which led me into a long period of productive research on animal behaviour and organic chemistry.

It occurred to me that the communication of ants and other social insects is triggered not by sights and sounds, but chemicals - substances these creatures can smell or taste. Earlier generations of entomologists had suggested something along these lines; after all, such creatures could not see in the darkness of their nests, and little evidence existed that they could hear airborne sounds. Some earlier writers believed ants communicated by tapping one another with their antennae and forelegs, using a kind of Morse code of the blind. But in 1953 we knew very little about the anatomical source of the chemicals that evoke the smells and tastes.

My research started with the fire ant, my favourite ant species since my college years - and one of the easiest insects to culture in the laboratory. The most conspicuous form of communication in fire ants is the laying of odour trails to food. Workers (the sterile, wingless females in the colony) acting as scouts leave the nest singly to search outward in paths forming irregular loops. When they encounter a particle of food too big or awkward to carry home in one trip, most commonly a dead insect or a sprink-ling of aphid honeydew, they head back to the nest in a more or less direct line while laying an odour trail. Some nestmates then follow this invisible path back to the food. The same method is used when a lone ant encounters an enemy, such as an army of rival ants.

As I watched while the fire ants were foraging, I noticed that the returning scout touched the tip of her abdomen (the rearmost part of the body) to the ground and extruded and dragged her sting for short intervals along the surface. The chemical releaser was apparently being paid out through the sting - like ink from a pen. Now I had to locate the source of the chemical, which I presumed to be inside the abdomen of the worker ant.

To take this next step, I needed to identify the organ making the chemical and use it to lay artificial trails of my own; I needed to steal the ants' signal and use it to speak to them myself, by smearing a microscopic fleck of the extracted semi-liquid matter outward from the ant nest.

The abdomen of a worker is the size of a grain of salt, and packed with organs barely visible to the naked eye. First I tried the hindgut, the poison gland, and the fat body, which together fill most of the abdominal cavity. Nothing happened. In the end I came to Dufour's gland, a tiny finger-shaped structure about which almost nothing was known. Might it contain the trail pheromone? Indeed it did. The response of the ants was explosive. I had expected a few to saunter away to see what might lie at the end of the new trail. What I got was a rush of dozens of excited ants. They tumbled over one another in their haste to follow the path I had blazed for them. As they ran along, they swept their antennae from side to side, sampling the molecules evaporating and diffusing through the air. At the end of the trail they milled about in confusion, searching for the reward not there.

That night I could not sleep; I had identified the first gland that contributes to ant communication. As I looked more closely at the fire-ant trail, I stumbled upon a second phenomenon of social behaviour - mass communication. The amount of food encountered or the approximate size of an enemy force cannot, I noticed, be transmitted by signals from a single scout. Such information can only be conveyed by groups of workers signalling to other groups, acting en masse rather than as individuals.

By laying trails on top of one another during a short interval of time, multiple workers, say a group of 10, can signal the existence of a far larger target than one identifiable by only a single worker. A hundred workers acting together can raise the range of the smell volume still more. When the food site becomes crowded or the enemy subdued, fewer workers in the group lay trails, so the excess pheromone evaporates, the signal diminishes, and a smaller number of nestmates thus respond. The information contained in the combined action of masses of individuals, rather than one, is surprisingly precise.

IN THESE studies of mass communication in ants, I was edging towards sociobiology - the new discipline I defined in 1975 as the "systematic study of the biological basis of social behaviour". The field I was operating in was more properly population biology, my perception being that an insect colony constituted a population. Some colonies, like the queen and 20- million-worker force of the African driver ant, have more inhabitants than entire countries.

Like human populations, the only way to understand such ensembles fully is to trace the lives and deaths of their separate members. This discipline alone addresses in concrete terms the heart of social organisation, from communication and nest construction to caste and the division of labour. What makes socio-biology different from population biology is a further ingredient - evolution. In sociobiology, behaviour and demographics are seen as the historical products of natural selection.

One area of special interest is allometry, the differential growth of certain organs in ant populations. Queens, soldiers and ordinary ("minor") workers display different physical characteristics. Allometry, by increasing or diminishing one dimension of the body relative to another, produces larger or smaller heads, full-blown or shrivelled ovaries, and other divergent products in any part of the final adult form.

When allometry and demography are closely joined, the probable evolution of caste becomes clearer. The anatomy of a particular caste member obviously determines the efficiency of its labour role; a soldier, for example, functions best with large, sharp mandibles and powerful muscles to close them. But the number of soldiers is also crucial. Too few fighting specialists, and the colony will be overwhelmed by enemies. Too many, and it cannot gather enough food to care for the young. It follows that colonies must regulate the birth rates - and, more significantly - the death rates of the various caste members created by allometry.

One of the classic problems in evolutionary theory is how self-sacrifice (such as the perishing of certain castes in vast numbers) can become a genetically fixed trait. Perhaps the survival of the community is important over and above the survival of the individual. If an altruistic act helps relatives, it increases the survival of genes identical to those of the altruist - just as is the case in parents and offspring. The genes are identical because the altruist and its relatives share a common ancestor. True, the corporeal self may die because of a selfless action, but the shared genes - including those that prescribe altruism - are actually benefited. The body may die, but the genes will flourish. In the enduring phrase of Richard Dawkins, social behaviour rides upon "the selfish gene".

! `Naturalist' by Edward O Wilson (Viking pounds 20) is available from all good bookshops or, in case of difficulty, from Penguin Direct, Bath Road, Harmondsworth, Middlesex UB7 0DA. UK service only; please add pounds 1.50 p&p.