The aquatics, Piscanthropus submarinus, (also known simply as aquas) are aquatic (as well as partly semiaquatic), ocean-dwelling, dugong-like humans, engineered from handler humans, first appearing in 300 years (the 23rd Century), in Man After Man: An Anthropology of the Future.
The sea waves, blasted by a southwestern gale, curdle and foam in cold blue slopes that march remorselessly across the desolate surface of the northern ocean. From the lead-grey sky the chill rain hisses down in the icy green hollows and is lost in the streaming foam of the crests. The sea surface is not a welcoming place.
Below the screaming, tumbling chaos of the surface and in the top few feet of the ocean water the gale is silenced, the waves suppressed to a gentle to-and-fro motion. Further down, the movement becomes weaker and weaker until it dies away completely. This is the world of the fish - and of the creatures that have abandoned their life on land to accept their ancestral home in the great oceans of the world. To some extent the sea otters did this, with their sinuous bodies and their webbed feet; the seals and walruses did it more efficiently with their streamlining and their flippers; but the now-extinct dolphins and the great whales and manatees did it to perfection, even adopting the almost fishlike ways of their forebears.
Now humans have done it too.
In the green half-light below the ocean's turbulence they swim. An unaccustomed eye might have taken them for dolphins, moving and turning, dashing away in a sudden streak, hanging for a while motionless.
They cannot breathe air, these creatures of the ocean. Instead they circulate the seawater through their mouths and pectoral gills, extracting the oxygen as it goes. They also feed constantly, filtering plankton through the same gills and transferring it to the digestive system. Now and again they take a fish - turning and streaking after it with a twist of the tailfin, a balance of the arms and a quick bite.
The tailfin is all that is left of the human legs. In embryo, the limb buds grow together and fuse into one organ. The hip girdle does not develop and the limb bones become almost an extension of the backbone. The phalanges of the toes spread and shape themselves into a network that supports the powerful diamond-shaped fin. The hands retain their human structure, but the arm has flattened and become modified into a balancing and stabilizing organ.
The development was started a century ago as part of the star-colony project, but the creatures developed were only partially successful. Later the engineering laboratories, in a last bid to produce something permanent before being closed down, refined the design and produced a truly aquatic human being; and (their final triumph) the genetic changes that they produced were actually hereditary. Yes, these newly-developed creatures were fertile, and produced viable offspring.
The process really started way back in the early days of civilization when man's quest to possess all the things of the world took him to the water. He invented mechanical devices that enabled him to take his air down into the sea with him and to breathe it at a workable pressure. Implements strapped to his body allowed him to see underwater and to swim with powerful leg strokes. As time went on great communities, rather like island cities, were established on the seabed. The sediment-choked ruins of these still litter the continental shelves. When genetic engineering was developed, gills could be cultivated from raw tissue and grafted onto the human body, enabling humans to breathe like fish. This was still clumsy and imprecise compared with the later engineering of a creature with no need of cities or artificial swimming and breathing devices.
What swims here is merely the surface race of the creature. In the blackness below, hundreds of fathoms down, others exist, rarely seen by any but their own kind, and even then they are not strictly "seen". In the blackness they can only feel their way about and communicate with one another by a kind of echolocation. These creatures are sluggish and inactive. There is little food at these depths and they must conserve what energy they have.
Since the aquatics rarely meet any other form of human, there is no enmity between them and any other group.
A female suckling a wriggling youngster undulates gracefully towards a group of males who are chasing fish. She speaks. The "voice" is a rattling sound, produced from clicks in the relict windpipe in the neck. The young males clatter their reply and swim off in what seems to be a random three-dimensional pattern. Suddenly the fish with which they were sporting congregate in a mass in front of the female's head, herded there by the precisely coordinated movements of the males. A quick flick and a snap, and she has swallowed one - the rest scattering into the green murk. She clucks her thanks to the males and swims sedately away. To look at, one would think that these are creatures that had existed in this environment since the world was young. It is only the face - a grotesque parody of the traditional human face, with big bulging eyes, tiny degenerate nose and downturned mouth - that shows it to be derived from a Homo sapiens.
By 1,000 years (the 30th Century)Beneath the tumultuous surface of the ocean, the aquas swim around in a leisurely fashion. Something is different, but they do not quite know what. The huge machine with its constantly-turning rotors and fans is now still and silent for the first time in memory. That is nothing to do with them - it was built by the strange beings from above the surface. The movement of water is different, but that has no effect on them either. The fish and the sea plants are still there. Even now the sea life is beginning to colonize the vast dead structures.
This may be a good thing for them. They do not now need to travel so far to find their food, and the new children that are born seem to have a better chance of survival now that food is more available. What is more the knowledge has gone out across the seabed, and aquas from other areas are moving in. It looks as if the population is growing quite fast in this area, and they no longer travel in small family groups. A whole interactive society may develop in this region, with all the advantages which that entails. Things may change from now on.
By 2,000 years (the 40th Century)Developed in the earliest centuries of genetic engineering as a refinement to the aquamorphs, the aquatics were the first group to carry hereditary genetic changes. Clumsy and vulnerable on land, the sea is now their instinctive habitat. Aquatics can move swiftly and powerfully within water. The ocean provides food and does not vary its temperature as swiftly as air - valuable when the increasing cold forces land-based species such as temperate woodland-dwellers into adaptation or retreat.
The tide seems to be going out further these days. Coom the temperate woodland-dweller is only a young lad, but he is sure that he can remember when the water came right up to the cliffs. Yes, sure enough, there is still a line of whitened tree trunks and bleached sticks, the remains of debris brought up by the waves long ago. His father is much older than he is, and can probably remember when the sea came right up to the foot of the cliff all the time. He might even remember it washing to the top of those austere stone faces.
Now the water is well out, leaving pools and puddles amongst the slippery, seaweed-covered rock. It will return, before the day is out, but it will not come anywhere near the cliffs. Coom thinks that it probably never will again.
He drops to all fours by the nearest of the tide pools. The empty woven-reed bag flops onto the cold rocks beside him. Nothing much in the water here. Further down, towards the edge of the sea, the pools will be more alive.
Here he has to be careful. The rocks are wet, seaweed-coated and slippery; and they are very cold beneath his feet. Now the cracks in the rocks are full of winkles, limpets lie flat and immobile against the wet algae-clad stone, and crabs scuttle and hide in the clear waters of the pools. With his long fingers, Coom pulls the shelly creatures away from their rocks, and dips into the cold waters for the crabs and sea anemones. It is meager fare, and even when his bag is full it will not give very much nourishment to this family.
He straightens up and looks back towards the cliff. There, in one of the caves along the foot, live his parents and his three brothers and sisters. It is a good thing, he thinks, that the sea does not come up to the cliffs anymore. He and his family would be washed away.
He is far enough down the beach now to see the mountains rising beyond the cliff. They are white, and have been for some time. He can remember, when he was very, very little, that sometimes they were green and purple. It is snow and ice that covers them, he knows that. Even the rocks and the cliff are covered in snow and ice now and again. Then a sudden thought strikes him - snow and ice are made of water, so could it be that, with so much more snow and ice over the land, the water has been taken from the sea, and that is why the sea does not come up to the cliff anymore?
A loud splash from behind him breaks his train of thought. Something big trapped in a pool! He turns quickly. At first he thinks it is a fish, but he has never seen a fish as big as that. Then he thinks it is one of his family who having slipped in is finding it difficult to get out, but no. It is neither of these.
It seems to be something in between.
The creature rises halfway out of the water. It has a face like his, with similar eyes, a nose and a mouth; but the eyes are enormous, the nose a pair of slits, and the mouth a vast downturned feature between huge fleshy lips. It has arms and hands, but the rest of the body is indistinct in the water. It seems to be smooth and shining.
Coom stares at the apparition, and it stares back at him. The great mouth begins to work, and sounds come out. It is trying to say something.
Is it dangerous? No, Coom does not think so; in a strange way it is almost like himself. He says a few words back to it, one or two of the few words that he and his family use, but that is no good. Whatever it is does not understand. Instead Coom tentatively reaches out his hand; the odd creature reaches out its own hand, and the two touch.
A friend! Coom has found a friend outside his family and species.
He lets drop the strange slippery hand, and turns to run back to the cave to tell everybody, full of joy and surprise at his discovery. His father is there, at the entrance, cracking open and scooping out a shellfish that the others of the family have brought him. Coom goes running up to him, grunting out his news. His father is all attention, as are his older brothers.
The result is unexpected. Coom is snarled at to move out of the way, then thrust into the cave while the others run off down the beach towards the sea.
That is not right, thinks Coom, that is not how it should have happened. They do not seem at all pleased about the new friend. He is not going to stay in the cave while all this is happening, so he runs down the rocks after them; but he is too late.
Already his father and his brothers are throwing rocks and bleached sticks at his new friend, and shouting the most hideous threats.
The strange creature, in panic, has pulled itself out of its tide pool, and is wriggling its way across the clammy seaweed and cold rocks towards the waves in blind terror, bleating out strange sounds as it goes. Coom stops. He does not want to be any closer, and see in more detail. He can imagine the weals and bruises on the glossy body, the blood from the fresh cuts, the look of anguish and pain on the outlandish face. He can only hope that the strange being reaches the water before his father and his brothers.
With sadness he watches it slip into the waves, beyond the gesturing figures of his family. A flip of the finlike tail and it is gone.
Well, his father must be always right. Coom considers the matter. He must have done wrong to try to befriend it in the first place. It is obvious that his people, the people of the land and the creatures of the sea will never be anything but enemies.
By 50,000 years (the 520th Century)As millennia pass, the aquatics become even more perfectly adapted to their seagoing existence. They become less bulky and more streamlined, with more efficient paddles and swimming organs. They begin to resemble the extinct seals and, like them, subsist on a diet of fish. However, they do not need to breath at the surface of the water. Their gills can extract all the oxygen they need from the sea. With the retreat of the pack ice, aquatics move into unknown waters. This is essential if they are to survive a steady increase in population.
In the green depths the school of aquatics works its way along the ocean bed. Spread out over a large area, each individual invisible to the next, the school keeps in tight contact by wails, clicks and twitterings (distinct but comprehensible sounds that form a language).The body of creatures moves northwards, along the lines of magnetic force which are becoming more powerful again as the centuries go by. The direction they take is north, as geography goes, but the magnetic influence that they follow is towards the south. Since the time when the magnetic field disappeared, producing the fatal effects on the technological civilizations of the time, a great change has taken place deep within the globe. The magnetic field has reestablished itself, but now there is a south pole where the North Pole once was, and a north pole where the South Pole once was. This reversal has little relevance to any of the creatures that now inhabit the world.
The water temperatures and currents are also changing, and this is leading to different patterns of fish movement around the globe. It may be that shoals of fish are gathering in areas unexplored by the aquatics, areas now free of pack ice. If that proves to be the case, then it will make sense to move into those areas. The tropics are becoming overfished.
The ocean never was particularly productive of food, considering that it covers more than two thirds of the surface of Earth. Back in the days of technological man, the living resources of the water were seized, exploited and lost in a short period of time. Since then nature has restocked, but the aquatics have always been there. Like the technological man that created them, the population of the aquatics has grown and grown. As they come to understand more about their own bodies, about diseases and injury and about reproduction, the birthrate has exceeded the death rate. Also, the lifespan of the individual has increased enormously and has been doing so for tens of thousands of years.
Around the coral reefs of the tropics the fish are vanishing, and the other valuable sea creatures are dying off. Undesirable and inedible species are moving in to replace them. The once beautiful and colorful fringing reefs, barrier reefs and atolls are now rapidly becoming dead skeletons of their former glory. It is not just the fault of the aquatics. The sea level is rising everywhere as well, and the tops of the reefs cannot grow quickly enough to keep pace with this. As the water becomes deeper and darker, the algae that grow with the corals and help them to feed are dying off, and the corals themselves are perishing. Although the aquatics cannot see color (the rod cells in their eyes were developed at the expense of the cone cells in order to increase their lowlight vision) they can see enough to know that their preferred environment is slowly dying. The aquatic colonies are everywhere in the shallows that surround the small tropical islands, becoming more and more crowded and more and more desperate for new resources, new food, new spaces.
That is why schools of them are moving northwards into the cooler waters; and others are turning their attention to a hostile environment - that above the surface of the ocean.
By 500,000 years (the 5020th Century)After many days of steady winds, five boats carrying 43 fugitive boat people see the first of the tropical islands that they plan to arrive at. It is as they expect. The first sign is a cloud on the horizon; blue hills appear next, then the green of lowland vegetation, and finally the white streak of beach. All is as predicted - except for the bubbles.
Several shining bouncing globes are moving up the beach. The puzzlement that they produce in the boatbuilders is short-lived, however, as the boats are caught in the rising swell of the shallowing sea. The waves that have pulsed unnoticed across the open ocean are now funneled and magnified as the seabed shallows, building up into steep walls of green water that curl over and crash into an oblivion of sparkling white spray and surge, hissing up the hot sandy beach. In this turmoil the boats heave upwards, dive into the hollows and are flung towards the land. As the prows crunch into the beach, the boatbuilders jump out, splashing ankle-deep in foam and sand, and drag their vessels to safety. Then, when all are safely ashore, they collapse onto the beach in joy and exhaustion. Although the voyage was completely predictable, because of their common memory, they have been very uneasy during their days at sea. That was not their environment at all.
One of their females notices it first: the huge translucent sphere beneath a sagging palm tree at the head of the beach. They had all seen the bubbles from the sea, but had ignored and then forgotten them. It was always the way that the inherited memory was more powerful than that developed by the individual. In size, the sphere could probably be encompassed by the outstretched arms of three boat people. It is shiny with a greenish tinge, and its base is spread and flattened by its own weight. Its outer covering seems flexible and the whole thing wobbles as it rolls slowly down the beach towards them. Sand adheres to its outside as it moves, but dries and drops away very quickly.
The female who first saw it stands and watches it roll right up to her. All watch, to see what happens next. Inherited memory cannot guide them now. Before there is time for reaction, a silvery arm shoots out of the side of the sphere, seizes her hand and tugs it inside. Then it starts rolling towards the water's edge, dragging the surprised female with it. When she realizes what is happening she begins to scream, but she and the sphere disappear beneath the surf before anyone can do anything about it.
The other travellers stare after her, stupidly. Then several more of the spheres appear at the head of the beach. They do not seem intent on attack - they roll towards the sea, avoiding the party. Anger, an emotion not often felt by the boatbuilders, surges to the surface, like one of the bursting waves, and as one they launch themselves in a revenge attack at the nearest sphere. Surrounded, the sphere cannot move, but it seems to waver, this way and that, to try to break free. Its surface is yielding but too tough to be penetrable. Blows and punches are absorbed and bounce right back. Then one of the boatbuilders brings a blade from one of the boats and plunges it into the glistening surface.
The sphere bursts, and a rush of salty water gushes over the attackers and sinks into the dry sand. The punctured surface has collapsed into slimy gel, releasing seawater. In the middle of the stain lies a strange creature, gasping.
Like them it has a black skin, but the skin is completely smooth and hairless. The head is like that of a fish, with big eyes that do not seem to be functioning in air. The mouth is huge and gaping. No neck separates the bulbous head from the streamlined body. Gills on the chest flap ineffectively, and the body narrows to a paddled tail. It is the arms, however, that are most remarkable: they are human arms, complete with hands and fingers. The thing flaps about on the beach pathetically as it slowly dies of suffocation.
The sea creature has devised some means of coming onto land and bringing its own environment with it. If these islands are now the domain of these creatures it is going to be difficult to settle here, for they have proved to be undeniably hostile.
Moreover, what will happen when the boatbuilders' pursuers arrive?
By 1 million years (the 10020th Century)As the aquatics spend more time on land, their tough protective bubbles refine and become more efficient. Eventually the gel becomes formfitting, holding the thinnest layer of life-giving seawater against the aquatic's body. This covering is enough to keep the skin moist, and to absorb oxygen from the air which is then absorbed through the gills. A steady increase in population among the aquatics has led to food shortages and famine. With the sea stripped bare, the aquatics face a hostile environment.
There is no more food growing here; it has all been cleared out. The ravaged soil has scraggy shoots sticking out of it, but it will be a long time before these grow and bear anything worth eating. Dead tree trunks stand gaunt and stripped, harsh splintery wood, killed by greed - no, not by greed, by necessity. The leaves had to be taken to feed the aquatics, but now the trek from the sea to the food is becoming longer and longer.
Ghloob peers through the watery film and the gelatinous envelope over his eyes. This work is dangerous and unpleasant, but the days of easy and pleasant life disappeared long before his birth. It is said that once the sea, their home, supplied all their needs, but then their numbers became too many, and all the food was gone. Famine raged. Whole populations perished and sank into the dark deeps. Sometimes after famine, the fish, krill and plankton would return, but this food source was never enough. As soon as it came back it was exploited and destroyed once more. Nothing can be done about it: if they want to survive they have to eat; if they eat they lose what they have and die.
It is as if there can never be a balance. They live there but they intrude on the natural system of things; and nothing that they do will make it any better.
Now they are exploiting the land as well, thanks to the algal mats that they have developed. Filamentous algae forming a fine mesh, impervious to water but permeable to air, can be induced to make shapes that will hold water. An aquatic can ascend from the ocean into the harsh sunlight and thin air above, still immersed in seawater, but contained in a flexible gelatinous envelope of alga filaments. Air passing through the envelope keeps the water aerated, and the aquatic neither desiccates nor suffocates, as long as the envelope holds.
Progress has been considerable. When the technique was first developed the envelope had to be spherical, holding a vast quantity of water. The adventurous aquatic moved along in this, rolling the squashy sphere around him or her, a cumbersome process. Now, and Ghloob cannot remember when it was otherwise, the envelope is formfitting. Only the thinnest of water layers surrounds him and protects him from the harsh world of the outside. Movement is still difficult, though, and always will be. He feels his own weight (an unknown sensation in his natural home) and he must pull his elongated body along the ground with his arms. If he is carrying something, he must wriggle along as best he can. Then he has to take care that the jagged denuded ground does not rip the envelope. No, this is not natural.
It has been good enough, though, to allow the aquatics to exploit all the lands that border the ocean. They sweep them clean of any growing or living thing, and do not give anything time to regrow. The teeming populations below the waves cannot wait.
In the distance, glimpsed hazily through the algal membrane, loom shapes that could be trees, or they could just as well be naked rocks. Aquatics had no color vision built into them when they were engineered, and none has evolved since.
He cannot communicate with his companions, but he hopes that his actions will be clear. He humps his long body, in its glistening envelope, in the direction of the shapes. The three others that are like him turn and follow. The fourth, the one encased in the spherical bubble that looks like one of the originals, is guided along by them. It is he who will enfold and carry home any food that they find.
They are travelling up a slope, which is not good. Distance from the sea is one thing, but height above its surface is another matter altogether. The aquatics live happily with the pressures experienced in the top layers of the ocean, but they are under considerable strain when exposed to the reduced pressures above the surface. To go any higher would produce all sorts of unwelcome effects in their tissues. An abrupt contour line, above which vegetation grows freely in many parts of the world, marks the limit of aquatic exploitation.
Beyond this contour line live the land people - strange beings who neither understand nor tolerate the aquatics.
There are the tree-dwellers, of whom the aquatics know little. They keep themselves in the branches away above. Aquatics rarely look upwards (it is difficult for them to do so), and so these beings are rarely seen.
Then there are the ground-dwellers. Savage and hostile, they feed in the undergrowth and the long-growing vegetation (the very materials that the aquatics harvest). Gangs of them have been known to burst out of hiding and set themselves upon harvesting groups, tearing at their protective membranes with claws and teeth, and sometimes inflicting some damage.
There is also the massive compound being, a huge basic creature, bloated and misshapen, lumbering through the forests with four or five spindly little figures attached to it, embedded in it, seeming to live off its flesh. These beings cause no trouble; in fact, they sometimes blunder out into harvesting parties where they are particularly vulnerable. In the open they are easily brought down and the moving reef of flesh can be killed by blows from an agile aquatic or drowned by being dragged within a membrane. The small attached creatures (tiny wizened bodies with spindly crablike legs and enormous mouths) become strangely pathetic without their mount and scuttle clumsily for cover. There is good eating on the fat creature and it is always borne back to the sea as a prize.
Finally there are the fighters, which are a menace, because they seem quite at home on the devastated areas left behind after harvesting. Their home is in the drier parts of the landmasses, where little grows anyway. They are organized, and many dozen can attack at once, moving as a single entity as if controlled by a single mind. Their forelimbs are cruel cutting weapons that can slice through a living membrane with a blow and kill the aquatic inside, so this time it is the aquatics who are the prey and their wet dead bodies are dragged away to the fighters' citadels. Of late, the attacks have been so organized that it is evident that the skirmishes are no longer defensive. Parties sally out with the firm intention of capturing and killing the harvesting aquatics. These beings must be left alone, and their domains avoided at any cost.
The shapes prove to be trees after all, but the undergrowth beneath them is patchy, curled and dead. Since the area down to the ocean has been devastated and left open to the sky, the air moving off the sea has swept in through the branches and between the trunks, drying up and battering the fragile stems and shriveling up the leaves. Loose sand and dust from the bare lands has gusted in, suffocating the more delicate types. There is little to be harvested here, but what there is must be taken.
Ghloob and his companions reach out their hands through the membranes and snatch up whatever is growing. Anything that is organic, and contains proteins and carbohydrates, can be used as the basis for food, however tough, however unpalatable. Bundles of leaves, stems, sticks, insects, slugs (anything) are caught up and passed into the sphere of the gathering aquatic. Small punctures in the membranes, like those caused when hands pass through, seal up immediately and there is little or no moisture loss.
Before long the cache within the spherical bubble has become quite large; large enough to take back. The five of them turn to make their laborious way back to their ocean home, glistening welcomingly away on the horizon.
No sooner have they left the shade of the dying trees, and begun their long slow descent, than Ghloob sees something at the periphery of his vision, something moving.
Slowly he turns his head. Ground-dwellers! A whole pack of them! They are running towards the aquatics, waving sticks of some kind. His companions see the danger at the same time, and try to move more quickly. However, their laborious humping motion is not conducive to haste, and anyway they cannot move faster than the spherical bubble containing their harvest - the only reason they are here in this hostile environment in the first place. The ground-dwellers quickly surround them, and as their hazy shapes appear before him Ghloob notices something different about them. They are each carrying something: something like a blade at the end of a stick.Ghloob has not much time to notice anything else, as he ducks out of the way to avoid them, but after heaving himself along the ground for some distance he turns to look back. The ground-dwellers have all set upon one of his companions. They have plunged their weapons into his membrane and are pulling it apart. With two creatures pulling in different directions this turns out to be very easy, and the membrane collapses in a gush of water leaving the stranded aquatic gasping in the circle of wet mud.
Ghloob and the others crawl frantically away, towards the tempting but distant sea, panic rising within them; with good reason, for the party of ground-dwellers leave the dying aquatic and come running after the straggler of the group and fling themselves upon him. Ghloob does not stay to watch this time, but keeps wriggling.
With every jump and jerk he expects to be attacked from behind, and his membrane torn away from him. The waves of the ocean come closer and closer, but agonizingly slowly. Will he make it before they catch him? He tries not to think about it, and keeps going.
With an intense feeling of joy he feels the pressure of the first wave close around him. He is safe, and at last he can look around. The bubble with one of his companions and the gathered food has reached the sea. The food is also safe, but at what cost? Three companions are lost - punctured, dehydrated and slaughtered on the distant dusty dryness.
The ground-dwellers have never fought like this before. Perhaps the aquatic harvesting has had such an effect on their lifestyle that they have had to adopt these extreme measures to fight back. Maybe the conflict and strife have forced them to find new ways of living and organizing themselves just to survive.
Ghloob's algal envelope dissipates now that he is fully submerged, and with graceful movements he descends the sloping seabed until he is below the push and pull of the waves, and home. Now he has time to ponder. Is this organization and use of weapons by the ground-dwellers to be a feature of all such attacks in the future? Has the aquatics' exploitation of the land made even that more hazardous? Is there nothing that we can do to feed our people without making things worse and worse and worse, and destroying everything that we have? Is this to be the continuing fate of intelligent life above and below the water?
By 2 million years (the 20020th Century)
It is morning. A gathering party of hivers, 100 strong, guided by a seeker one sterile female is carrying, takes its usual route along the undulating foothills, skirting the dreadful slimelands on the right, and the barren rocky uplands on the left. Beyond, the slope widens out into a valley in which water flows for much of the year, and where plants can grow and there are usually tubers or thick roots to be had. Before their narrow path widens, they encounter and then immediately ignore five or six shambling hosts moving down the rocky slope towards the slimelands.
Had the party stayed to watch, they would have observed the lumbering creatures scramble down into the flats of the slimelands and wade out amongst the disgusting blue-green sogginess. Dumbly they scoop up handfuls of the slime, exposing the yellow stench beneath, and begin to feed on it. The parasites embedded in their fat ignore all this. The food, be it nuts, leaves or slime, will be converted into huge deposits of fat and tissue that will sustain them.
The hosts are descended from tundra-dwellers, but unlike the now extinct symbiont carriers they changed as the conditions changed. Gone are the woolly coats and the resistance to extreme cold, but they still retain the thick deposits of fat. Indeed their metabolism generates more fat than they could possibly need, and that is what sustains the parasites. The energy and raw materials for all this production comes from the constant consumption of plants - any kind of plants and similar organisms, including the blue-green algal cultures that the aquatics developed as their own food source and spread over the lowland areas of the globe, turning them into the foul, low-lying slimelands so despised by most of the land-living creatures.
It is not only the hivers that ignore the parasites and their hosts as they wade into the featureless slippery mat. Also ignoring them are the aquatics, not far away, looping and slithering about in the moist yellow depths below the slime crust. They are grazing their way through the algal culture that their ancestors established ages ago on the lowlands above the surface of the ocean. There is plenty of food for them now, not like in the days of want. They know very well that some creatures from the land come and steal from the edges, but the losses are small. The only trouble is dehydration. If the algal covering is breached there may be a considerable water loss before it has a chance to grow again; but with all the world's lowlands covered in the self-sustaining food-generator there is little to worry about.
By 3 million years (the 30020th Century)
The algae that were induced to grow on the lowlands by the aquatics have absorbed much of the atmospheric carbon dioxide, and now it lies trapped in vast deposits of peat and lignite below the roots of the forests of the coastal plains. The aquatics themselves have long ago abandoned that wasteful exercise, and now grow more concentrated food out at sea.
By 5 million years (the 50020th Century)
Out in the oceans, the teeming aquatics know little of what happens above their watery ceiling. They can hardly comprehend the existence of life on land, let alone the nature of the moving stars in the sky.
When the Travelers of the stars arrive, decades later, they wipe out most of the aquatics.
Centuries later, the newcomers abandon the planet, life may mostly be destroyed, but there is still hope.
The aquatics that have survived have evolved into Piscanthropus profundus.