Other young queens around the Trailhead Queen were digging in on their own. All failed: one by one predators killed them. No sister worked side by side with the Trailhead Queen, no worker had yet been born that could support her. Outside the sisterhood of the mother colony that produced her, nature remained a battleground in a pitiless and total war every minute of the day. Intruders winkled the survivors out of their little nests and ate them. Other risks were present inside the nests themselves: the eggs might not be properly inseminated, or the sperm might be genetically defective.
But the dice fell right time and time again for the future Queen of the Trailhead Colony. As tiny larvae hatched from her eggs, she fed them highly nutritious food secreted from a large gland that partly filled her head and emptied through her mouth. This baby food was manufactured from masses of fat stored in the rear segment of the Queen's body. It was also created by metabolism of her now-useless wing muscles.
From the reserves of her own body the young Queen reared a dozen workers. All were female. They were tiny and weak, barely able to perform the work necessary for the little colony to survive. By necessity they came into the world as midgets. If each were larger in size, fewer of them could have been raised. The number would have fallen below the level necessary to provide adequate labor for the survival of the newborn colony.
Some of these pioneers, guided entirely by instinct because no one existed to teach them, set out to forage for food. Others took care of the Queen and reared the next generation of workers to maturity. Still others devoted time to enlarging the nest. Failure to perform all these tasks with exactitude would mean death for the colony. The young Queen could help no more. On the contrary, she desperately needed help herself to continue living. Her expendable body tissues were depleted. They had almost all been fed to the larval daughters, and now she was starving. Her body was a shell of chitin containing only tissues necessary for her own life. The first foragers venturing timidly away from the nest were able to bring back a few scraps of food. Their prizes included a fallen mosquito, a bit of shed caterpillar skin, and a newly hatched spiderling, which were enough to keep the colony alive and allow the Queen to regain some of her weight and strength.
Workers of the next generation, raised on food harvested from terrain outside the nest, were somewhat larger in physical size than the first generation, and stronger. They began to dig out many more tunnels to accommodate the growing population. As the colony and their habitation grew, the endangered home assumed the form of a labyrinth of chambers and connecting galleries. It became an enemy-proof fortress. A mound of excavated soil formed above it, reinforcing the roof and capturing the warmth of the sun.
As the months passed, the Queen, growing heavy with eggfilled ovaries, retreated ever deeper, distancing herself from the still-dangerous nest exterior. She had become an extreme specialist. She alone laid eggs, she alone was the growing tip of the burgeoning colony. The workers performed all the labor needed to raise her offspring, their sisters. They were the Queen's hands and feet and jaws, and increasingly they replaced her brain. They functioned together as a well-organized whole. They were altruistic toward one another, and they divided labor without regard to their own welfare. The Trailhead Colony came to resemble a large, diffuse organism. In a word, it became a superorganism.
By the time the colony reached its full mature size two years after the nuptial flight of the Queen, it contained over ten thousand workers. It was then able, in the following year, to rear virgin queens, and males, and from them to give birth to new colonies. By that time the Queen was producing eggs at the average rate of one every fifteen minutes. Heavy and torpid, she lay in the royal chamber at the bottom of the subterranean nest, five feet below the surface, a distance of four hundred ant lengths. By human scale the ant city was the equivalent of two hundred underground stories. The mound of excavated soil capping the nest added another fifty stories aboveground.
The Queen may not have been the leader of this miniature civilization, but she was the fountainhead of all its energies and growth. She was the key to its success or failure. The metronomic pumping out of fertilized eggs from her twenty ovaries was the heartbeat of the colony. That it should continue strong and true was the ultimate purpose of all the workers' labor. Their careful construction of the nest labyrinth, their readiness to risk life in daily searches for food abroad, their suicidal defense of the nest entrance, all their sacrifices were for her and for the creation of more altruistic workers like themselves.
One worker, or a thousand workers, could die and the colony would go on, repairing itself as needed. But the failure of the Queen, if not corrected, would be fatal.
Now after twenty more years that catastrophe had occurred. The death of the Queen was the greatest challenge the colony had faced since the days of its founding. Yet the workers could not take action until they learned for certain that the Queen was dead. They knew that something was not right, that something unnamed had settled upon them, but they did not yet realize the extent of her problem. The signs were not yet strong enough. So the Trailhead Colony thrummed on for a while longer with bustle and precision. Like a large ship at sea, it could not be easily turned from the shoals coming at it.
The reason for the continued momentum of the Trailhead Colony lay in the way ants communicate. Because they live most of their lives in underground darkness, they cannot speak to each other with sight or sound. Instead, they are forced to communicate with chemical signals. Human beings think in sound and vision. Ants, forced to be pheromonal, think only in taste and smell. No human can understand the chemical sensations that crowd the brain of a worker ant. We have no understanding of the entities she conceives, or the tones, the accounts, and the blends that course through her mind. While the Trailhead Colony may have been silent to unaided human perception, it was thunderous with pheromonal chatter among the ants.
The Trailhead Colony communicated using about a dozen chemical signals. The retinue of workers crowded around their dead mother were locked to her by several of these pheromones still oozing from her body. Translated into a human voice, they whispered a ghostly command: Come here, gather around me, stay close to me.
The attendants licked her body lasciviously with their pad-shaped tongues. They continued eagerly to clean her, picking up substances from her to pass on to others outside the retinue. The pheromones that triggered their intimate care spoke through taste and smell: Wash me, eat the substances you clean from my body, share them with your sisters.
The substances commanding the retinue were held in the forward chamber of the gut of each of the ants. They mingled there with liquid food. The ants smelled each other constantly by sweeps of their antennae, the "feelers" on their heads, the equivalent of the human nose. An ant that was well fed, with lots of food resting in her gut, said to a less well-fed nestmate, Smell this, and if you are hungry, eat. If the ant approached and was in fact hungry, she extended her tongue, and the donor ant rewarded her by regurgitating liquid directly into her mouth.
The exchanges among the sisters continued in this way. The combined intelligence of the colony listened to the flood of crosstalk among its members. They spoke in pheromones in all the messages they were programmed to send and receive. The colony exchanged information within itself in the same way the body of one ant, one human, or any other single organism exchanges information within itself by hormones. The superorganism pheromones suggested, begged, and commanded.
Outside the nest, not far from the Trailheader mound, a wood thrush flew by one day carrying a grasshopper to her own nest. Part of the crushed insect broke off and fell to the ground. In less than a minute a patrolling worker found it, triggering a chain of action of the kind followed countless times by Trailheaders before. She examined the grasshopper, tasted it briefly, and ran back to the nest entrance. On the way, she touched the tip of her abdomen to the ground, laying down a thin trail of chemicals. Entering the nest, she rushed up to each nestmate she passed, brushing h
er face close to theirs. The odor-sensitive antennae of the nestmates detected both the trail substance and the smell of grasshopper. The signals now proclaimed, Food, food. I have found food, follow my trail!
Soon a mob of ants ran out. They followed the trail, and gathered around the delicious haunch of grasshopper. Some of the first to arrive ran back to the nest, laying trails of their own, reinforcing the message, saying, Come on, come on, we need help.
The ants working on the grasshopper piece began to drag it toward the nest entrance. A catbird perched on the branch of a tree nearby saw the activity and swept down to investigate. She pecked at the grasshopper, scattering the ants and injuring several. The ants expelled a pheromone from a gland that opened at the base of their jaws. A chemical vapor spread fast. It shouted, Danger! Emergency! Run! Run! Get out of here!
And so the business of the Trailhead Colony was conducted by a vocabulary of odor and taste. Pheromones were emitted, occasionally reinforced by touch. Messages were created, sometimes with a single chemical substance, sometimes with the same substance at different concentrations, and on occasion two or more in combination. Meanings were changed according to where the substances were delivered. The vocabulary grew. Different messages were delivered.
Here, let me lick and clean you.
Get to work, do what others are doing here.
This is my caste, and this is my condition.
Let us lay down territorial pheromones, announcing to rivals our dominion over this land.
We don't have enough soldiers; raise more in the nursery.
We have too many soldiers; raise fewer.
Who is leading the struggle to become our new Queen?
The members of the Trailhead Colony lived every second of their lives by instructions in the clouds and torrents of pheromones around them. Some signals such as the alarm pheromones spread and faded fast, drawing the attention of many nestmates as needed locally, but not holding on long enough to create panic throughout the colony. At the opposite extreme, some odors spread slowly and lasted a long time. Among them were the royal pheromones of the Trailhead Queen. Even as her body began to decay, the pheromones she had manufactured in life persisted in the minds and bodies of her colony.
The royal presence had been woven into the pheromone life of the Trailhead Colony a second way. Her secretions were blended with other substances to create an odor unique to the colony as a whole. The odorants were absorbed into the waxy cuticle that covered the body of every member of the colony. Each colony of ants had a personal bouquet that all its members shared and learned and to which they remained absolutely faithful. When two ants met, regardless of their origins, they both swept their antennae back and forth over the other. The movement was too swift for the unaided human eye to follow, but the brain of each ant almost instantly processed the information. If the two ants shared the same odor, the message was, She belongs to my colony, no other. The two then either continued on their way without pause, or paused to groom each other, or exchanged food. If, on the other hand, their odors differed even slightly, the message was, Different colony, look out! Like strange dogs meeting in the street, two ants of separate origin stopped to examine each other more carefully. They then either launched an attack or ran from each other.
No words, no signals of motion were used to establish an ant's tribal identity. None was needed. The Trailhead Colony was united simply and entirely by possession of the same smell. If that were to disappear, the superorganism would quickly dissolve into a mob of disoriented organisms. They would fight among themselves. Enemies would scatter them. Predators would close in for an easy meal.
The Trailhead Queen lay in state. It could not last forever. Eventually parts of her body were eaten and the rest carried away to the ant cemetery. For a week the pheromones licked off the remaining fragments continued to broadcast her existential message. Thereafter the chemicals gradually dissipated, and at last the message faded away.
A few chemical signs appeared early, but it was on the third day after she died that the Queen's pheromones began to be overlaid by the faint evidence of death. Her overall odor became ambiguous, and with it the posthumous messages she sent. Still, nothing mattered in the recognition of her corpse other than the odor of decay. Visual appearance and the cessation of movement meant nothing. The Queen could have lain on her back with her legs held rigidly up in the air. She could have turned any color: red, black, metallic gold, or any other hue or shade, it would not matter. Instead, the Queen had to smell dead in order to be classified as dead. And not from the blends of substances in corpses repellent to the human nose--not, for example, from the loathsome skatole and indole that distinguish human feces, nor the trimethylamine that rises dramatically from spoiled fish. Such chemicals, when encountered alone, would cause alarm in the ants and repel them. The same was true of other volatile toxic substances. Only oleic acid and its ester, which are decomposition products of fat, were effective messengers of death. They mean little or nothing to the human nose. But they mean dead to an ant. When encountered on the corpse of a nestmate, they caused the ants to pick it up and carry it away for disposal.
Within a week, the constant licking of the royal corpse in the Trailhead Colony started to break it into pieces. One by one the fragments, reeking of the oleic compounds, were carried out of the royal chamber. Unknowingly the ants bade farewell to their mother. No ceremony was performed. Instead the workers bearing the body parts wandered alone through the nest galleries in search of the Trailheader cemetery. This special place was not marked by ceremonial trappings. It had no special shape, nor did it contain any token of remembrance, even for a queen. It was merely a chamber at the periphery of the underground nest. The ants dumped all kinds of debris into it, including discarded cocoons shed by newly emerged adults, inedible parts of prey, and deceased colony members.
When the corpse carriers came close to the refuse chamber, they turned their burdens over to cemetery workers. These specialists were ants who constantly rearranged and added to the refuse piles. They stayed close to their work and were for the most part avoided by their nestmates.
In cemetery work and all other activities, the Trailhead Colony organized its labor by altruistic rules of labor specialization. Everything they did was restrained by some degree of self-sacrificial altruism. Above all, the workers had given up the chance to reproduce, at least so long as the Queen was alive and healthy. They accepted service in foraging, soldiering, and other dangerous occupations that increased their risk, often to the point of certain early death. The dominance of the Trailhead Colony over its individual member ants was total. The welfare of the superorganism was paramount, and a worker's life story was programmed to be subordinate to the superorganism's needs. If a worker died, the loss weakened the colony to some measurable but relatively inconsequential extent. The deficit could be quickly made up by rearing another worker in the nursery. If, on the other hand, a worker behaved in a selfish manner, consuming for a good part of its life more resources than it contributed, it weakened the colony far more than if it just had the decency to desert or die.
The decency of ants was, in disability, to leave and trouble no more. The self-sacrifices that led to the success of the Trailhead Colony were evident in every task performed by all of the worker force in all circumstances. The sick and injured received no care. In fact, they avoided such attention, moving on their own to the outermost nest chambers. The disabled were among the colony's most aggressive fighters. Dying workers often left the nest completely, thereby avoiding the spread of infectious diseases.
Older workers that stayed healthy but were approaching the end of their natural life-span also emigrated to the nest perimeter. From there they were prone to become foragers, leaving the nest to search for food, which exposed them to a much higher risk from enemies. When defending the nest, elders were among the most suicidally aggressive. They were obedient to a simple truth that separates our two species: where humans send their young men t
o war, ants send their old ladies.
The Queen had been the exclusive reproducer of the colony, the mother of the entirety of its inhabitants and the new colonies they were able to produce. All the sacrifices offered by the workers were made to protect her life and to enhance her fertility. Whether the Trailhead Colony would now live or die depended upon its ability to replace the mother Queen. That would require all their skill in retaining their strength until a new Queen was installed.
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AT THIS POINT the ancient colony seemed doomed. Grow or die was the iron law it must obey. Population growth, positive or negative, up or down, is of life-and-death importance to any ant colony. Constant population growth and ever-rising productivity in the nurseries are the superorganism's bottom line. Both social and personal life are geared to serve this central purpose. The reason is elementary: the larger the colony, the greater its net growth, and hence the more virgin queens and males it can contribute to the next generation of colonies. Genes that prescribe robust colony growth spread across the land and through the species as a whole; those that do not prescribe robust growth shrink before the expanding Darwinian winners, and disappear.
The Trailheader myrmidons themselves instinctively knew they were in trouble. In time the chemical signals had dropped to a hardly detectable level in the outermost reaches of the nest. The workers began to understand that their Queen was incompetent.
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