10,000 YEARS HENCE SYMBIONT CARRIER Baiulus moderatorum Two species form a single unit of value to both – symbiosis. The woodland-dwellers have skills that their carriers lack. The hunting ability of the swift forest-dweller provides enough food both for itself and its slow-moving carrier. The tundra-dweller, in turn, provides both with general movement and protection against the cold.	Lacking thick fur and insulating layers of fat, Moderator baiuli can only hunt in short bursts before needing to return to the body heat of its carrier. Communication is by touch.

If the movement of the rodents is remarkable, what then happens to the symbionts is even more strange: about half of the individuals fall apart, literally. Each one resolves itself into two separate creatures. The huge hairy arms of the tundra-dweller that were clutched across its chest open up like doors, and to the ground drops a spindly figure – the owner of the second head and the pointing arm. The slimly-built creatures are running as soon as they hit the ground, and ten of them plunge into the moving mass of lemmings, snatching and killing as they go. The remaining symbionts, mostly females and young, stand watching, shouting encouragement in words and noises that only members of their own group can understand. The tundra-dweller shapes vacated by the hunters stand immobile and silent.
After a while the hunters gather up the rodents that they have killed and bring them back to the group. They are handed around to the figures clutched to the bosoms of the tundra-dwellers. Then each hunter returns to its own tundra-dweller/carrier and, with a touch and a word, it is gathered up into the great arms. For a while they eat. Each lemming is partly eaten by the being at the symbiont’s chest, but then the greater part of it is handed up to the great mouth in the head above. The tundra-dweller part of the creature receives the food passively, and eats it all.
This strange state of affairs began thousands of years ago. When the hunters (the humans that had been engineered to live in the temperate forests) spread out to hunt on the tundra, with the coming of the current ice age they had to adopt all kinds of strategies to keep themselves warm and to survive. Some found that they could live close to the dull tundra-dwellers and share their body heat. The tundra-dwellers did not mind this, if the hunters shared their food with them. So the symbiotic situation gradually developed, until now the hunters could not travel by themselves in the tundra and these particular tundra-dwellers would not be able to survive on their own.
Once the food is eaten, the group sets off again. The smaller hunters can talk to one another, using a simple language, but each communicates with its tundra-dweller/carrier by nudges and gestures – a pointing of the arm is enough to tell the carrier to go, and which way. They follow the lemming march, as there will be good eating here for a day or two.

HIBERNATORS

The trance-like state is not now as deep as it was a few days ago. The warmth of spring is filtering through the cocoon’s insulating layers of fibre and wood, registering slowly on the dulled nerves and sensory system of the sleeper, triggering a slow increase in his metabolism and bringing consciousness nearer. His mind emerges from total blankness into a dream state, in which he relives and consolidates the hunting and gathering techniques that he learned last season. In his dream he sees the forest of his home, firstly as it was when he was a child, then as it was more recently. The most recent memory-dream is of his mate of last season, and hopefully of this season also, and the thought of her excites him so much that the final barrier of conciousness is broken, and he is awake.
With a groan of momentary disappointment that the last vision was only a dream, he stretches himself, pulling open his eyelids against the mucus that gums them together, and unfolding his limbs which are so stiff that they almost creak. With a struggle he breaks through the covering of vegetable matter and into the spring smells of the coniferous forest.
The spring flowers — the gentians, orchids and saxifrages – are out and blooming, as they are whenever he awakes from his winter sleep, but the sun is low in the sky. Spring is early this year, therefore the climate must be becoming warmer.
Then the pain of hunger strikes him and he digs at the remains of his food store. Several times throughout the dark winter he broke his trance to feed and now there is little left. Most of the tubers have rotted and the seeds germinated, but there are still a number of items that are edible. These he devours with no hesitation, to give him the strength to look for more.
There is plenty of food about, since it is the beginning of the time of swarming insects and the damp soil and decaying needles underfoot house a vast array of luscious wriggling things. Beneath the bark of the trees, too, grubs and beetles burrow and tunnel in their millions, and birds are here as well, having travelled up from the south, as his mate will hopefully do, to feed on the insects. When his stiffness has worn off, and he has built up his strength again he will also be able to catch the birds and the little rodents that have come out to feed on the tender shoots and saplings.
Looking for food, he rips the bark from a fallen tree, one which must have died during the winter. He remembers when it was merely a sapling – over 60 years ago, but numbers mean nothing to him. He only remembers.
After building up his strength for a few days he sets about the task of building his fortress. It will be made of wood, comfortable and soft inside, but harsh, jagged and defensive outside. It needs to be, since there are many marauding males about that would fight him to death for a fertile female like his. He builds his fortress on what remains of last season’s, and that is quite a lot. As the years go by his building techniques improve and his structures become more durable.
Little remains, however, of the guide walls, and these have to be rebuilt every spring. Reaching out in two directions in a huge V-shape, open end to the south and with the fortress at the apex, the structure stretches for over 2000 paces in each direction. It is made of sticks pushed into the ground and thinner sticks woven in between. It is not meant to be a barrier, but more of a marker across the landscape. His mate has wintered in the milder climates away to the south, and will be travelling northwards very soon. It is essential that she does not miss the fortress and go blundering on northwards, or end up in some other male’s domain.
With construction completed, he starts to build up the food supplies in the fortress itself. After a few days he hears an excited chatter, and he looks expectantly from the mouth of the now comfortable fortress. She is there, walking confidently up the side of the barrier.
Yes, she carries the winter’s baby with her.
With joy, one of the few emotions he can feel, he rushes to meet them, and to fondle her and stroke the child he sees for the first time. A female. That is good: there are enough males around. This is the first child that he has had by this female, although he has had many others by other mates.
Females are much shorter-lived than males. They cannot sleep the cold times away, as they have to travel south to give birth in the winter. Many of his females aged and died during his life, while many others became lost in the migration, dying on the trek or ending up in other fortresses.
Each creature has its allotted life span. Barring accident or disease it survives for about 2000 million heartbeats. For the migrating females these heartbeats average about 70 per minute. For the hibernating male this average is kept up during waking times, but during the late autumn, winter and early spring it drops to about 20 per minute. The remainder of his bodily functions slow down accordingly. As a result the male’s lifespan is between four and five times the length of the female’s.
In the dimness of his weak imagination he sometimes thinks that it would be better if babies were born during the summer so that they could all hibernate together; but this would not be possible unless the growth of a baby inside the female could be speeded up or slowed down, so that the offspring of the spring mating emerged at a more convenient time.
That cannot be... yet.

LEADER OF THE CLAN

There is no way across the water any more. In times past, low water exposed broad expanses of brown rippled mud, with winding glistening creeks, joining the flat marshes of the clan’s domain and the infinite woodlands of the country beyond. At these times the clan could squelch across the mud, churning up the black stinking subsurface, and go on short forays amongst the trees and forests of the mainland.
That is no longer possible for the mud flats are now permanently submerged. The clan can know nothing of the reason, the shrinking icecap thousands of kilometres to the north. They would not understand that the melting ice is pouring water back into the oceans, and that the sea levels are rising worldwide. They only realize that the island on which they now live is more isolated than it has ever been at any time they can remember.
It does not disturb them. The woods and marshes of the island supply plenty of food for the small numbers that live there, and the rainy climate provides enough drinking water. It has been only occasionally, in times of severe hardship, that any of them have actually crossed the mud to the mainland to forage. Mathematics and measurement do not come into their lifestyle at all, but if they did they would realize that the 200 square kilometres of the island are just able to support the 20 individuals of the clan.
The leader thinks of it in another way. He can walk right across the island in half a day. This walk takes him through bushes with fruit and undergrowth with tubers, and between the trunks of trees with nuts. Everywhere there are birds and small animals that can be caught. Walking around the coast takes three days of daylight, and takes him across beaches with burrowing creatures, over rocks with attached shellfish, and through saltmarshes full of birds. A clan the size of his is well supplied, for the moment.
There were times when food was short, and they all went onto the mainland; but that has always been dangerous. Other clans live there, and they do not take to strangers. Now they will have to deal with any shortages in some other way.
Certainly it will be best if the clan does not grow any more. More mouths to feed will be a disaster. If they can all eat less as well, it will help. The leader cannot anticipate any of this. His whole attention is taken up in ensuring that all his people have enough food. He has noticed, however, that one of his daughters, a very big-boned and heavy female, becomes hungry and ill more often these days. At the same time another of his daughters, this one very much smaller and more lightly-built than her sisters and brothers, has a small appetite and is the healthiest of the whole clan. She will certainly reach maturity and breed.

DISAPPEARANCE OF THE PLAINS

Rain falls. It now falls for long periods and the grasslands are losing their character. Instead of one short rainy season in the year followed by long periods of dryness, there is now more rain all year round.
The grasses thrived under the old conditions. Their tops were shrivelled off by the sun, grazed away by animals and burned by periodic bush fires, but they survived because of their protected underground stems, and grew again from ground level. Few trees or bushes flourished under these conditions, but the plains dwellers also did well here. Their exclusive diet of grass meant that they could live here where no other large creature lived. They could spend the dry seasons in the thorn thickets that bordered the grasslands and separated them from the humid tropical forests of the equator, and they migrated out over the grasslands proper during the wet season, feeding as they went. Other large creatures could not cope with this existence.
Now, with the more frequent rains, the thorn forest is spreading over the plains, and trees are growing where once there was only grass. With the new conditions different creatures, ones that hunt meat for food, are creeping out of the tropical forests. More and more often the plains dwellers have to take themselves off out of danger. With their immensely long legs they can quickly outpace any enemy, but this is becoming more and more frequent. It is wasting a great deal of energy and eroding valuable eating time.
Over the past few thousand years the plains-dwellers have faced problems like this, many times. Sometimes, when it seemed as if the grasslands were going to disappear, herds of them went through the thorn thickets and into the depths of the great rainforests, in the hope of finding new pasture. None ever returned. Few went the other way, where the grasses became shorter and sparser, where food became harder and harder to find, and where even small creatures became rarer and more difficult to see. The grasses in this direction eventually gave way to rocky and sandy wastes, where the rainy season was even shorter and less reliable than it was on the plains. In these previous times of crisis, however, the problem was never long-lived: the grasslands established themselves once more.
Now, with the increased rainfall, the grasses as the plains-dwellers knew them are becoming obliterated by thorn forest. The only reliable expanses of grass seem now to be found in the once-desert areas, and even these unbeckoning wastes are changing because of the increased moisture. Grasses and low plants are finding purchase in the harsh rocky soil that once they found uninhabitable. Perhaps in this direction lies the future home of the lanky plains-dwellers.

CAVE-DWELLERS

It has been, after all, just another temporary respite. The cold weather returns. Winter becomes long and bitter, while summer dwindles into the briefest of seasons, unable to melt the snows deposited the winter before. The southward movement of glaciers is again faster than the northward melting of their snouts, and the icesheets spread into the plains and lowlands of much of the northern hemisphere.
He seems to retire into his hibernation earlier and earlier each year, and his sleep lasts longer and longer. At least the fish have still been coming to the stream outside his sleeping cave. There was always food available for him in the narrow valley.
This year, however, it is different. After he awakes, he can hardly approach the entrance of the cave, so bright is the glare of the snow outside. He waits for night to fall, so that the outside light will not hurt his eyes after his long slumber. In his hunger he chews the moss from the cave walls and the fungus from the floor. After a while the light fades, and he prepares to face the outer cold. Suddenly, there is a strange screeching noise from deep within the cave behind him. It becomes louder and, with a flurry of wings, a black flock of bats hurtles upwards from the depths and out through the cave mouth. In a reflex, stiff from long hibernation but still good enough for the purpose, he shoots out his arm and grabs one of the furry creatures from the air. It squeals once as it dies, and he eats it whole, chopping up the body with his sharp front teeth and grinding up the little bones with the massive molars at the back. The warm blood and juices warm his inside, and presently he begins to feel fully awake. The torrent of bats is still blasting out of the cave mouth, and he grabs another to eat.
There is now no need to go outside. The humble plants at the cave entrance and the unending supply of bats could keep him alive here for ever. Then he remembers that there are birds that nest here, too, high up in the cracks and gullies of the cavern walls, and small shrimps and insects in the running waters deep down. These will be good for eating as well. He does not need to go outside in the cold, at least not tonight. He turns his back on the grey entrance and begins to grope his way back down the tunnels into the comfortable depths.
Dimly he wonders if any others of his type realize how much food there is to be had down here. Sometime he will go out into the chill and find some of them and bring them down.
Another time. Tonight he has food to find.

CONTENTS