The fatty deposit across its shoulders can be depleted but not yet exhausted. Bat-like ears radiate waste heat. Although similar in appearance to a hiver, the desert-runner's ancestors originated in the temperate woodland. Through convergent evolution, the desert-runners are beginning to adopt the shape that was designed into the plains-dwellers all those millions of years before. However, the runners are carnivorous, unlike the hivers.
The Sun burns blisteringly down, baking all the landscape and beating up from the sharp naked rocks and the pockets of dry dust that lie between. All is yellow and grey, and no plants are to be seen anywhere. In a wadi (a gushing torrent in the distant rainy season but now a parched gully) the sand lies deep and barren. The only sound is the distant hum of the wind, and the constant hiss of sand as it is blasted against the rocks and swirled about in the hollows. The monotony is broken by a faint scrabbling sound as a brown lizard scuttles amongst the loose stones and vanishes into their shadows, then all is stillness again. Few things venture out in the killing heat and dryness of the desert noon.
Yet in the distance something large is moving, and moving quite swiftly too. Its legs and arms are long and thin, and its head seems inordinately large, covered in white hair and surmounted by a pair of huge ears. It looks like one of the hivers, but it is travelling and hunting alone. It is, in fact, one of the hunters that has evolved and adapted to the harsh conditions of the desert - a desert-runner.
His long strides take him swiftly across the scorching wadi and into the sharp blackness of the rock shadow at the other side. There he rests, looking out at the dazzling sand with his polarized dark-lensed eyes. He sees things only in black and white, as the rod cells of his eye have developed at the expense of the cones, increasing his distant and night vision. He has just travelled many miles over the rocks and dust and will now rest a while to cool his body. Despite his adaptations to life in the desert he must still guard against the killing heat of the Sun and the dryness of the wind. The fatty hump behind his neck is almost depleted, the store of fat having been turned into energy. Nevertheless, he knows that he will soon reach a fertile spot where his stores can be replenished.
The hump is only one adaptation to the dry heat of the desert. Greatly-enhanced kidneys distill and use every drop of water that enters the body. Waste heat is radiated from the body by means of the great bat-like ears, acting as heat-exchangers, and the long thin legs that give a very large surface area for the mass of the body. These are necessary, since no sweat exudes from the skin - all water is saved. The ears, eyes and nostrils have thick folds of skin that can close them off and keep out sand and dust when the winds get too high.
The Sun has now passed its zenith, and the black desert shadows are lengthening. Rested now, the desert-runner creeps out to continue his journey. The first part of his travel was over sand, where he used his long legs, with their light elongated foot bones powered by the concentration of muscles in the thigh. Now his way takes him over naked rock, so his passage is slower, using his long toes and gripping fingers to find purchase in the cracks and joints of the hot crumbly stone. As the Sun descends into the dusty haze of evening, his goal is in sight.
The hive looks like one of the rocky hills that surround it. Its vast roof slabs look just like the horizontal strata of the surrounding rocks, and the black entrances just like the wind-blasted caves of the dusty crags. Just as desert-living humans evolved along the lines of the desert nonhuman animals, the desert cities of the hivers developed along the lines of their habitats. The vast thick roofs paralleled the flat stones that absorbed the heat of the Sun and protected the creatures that existed underneath. The tunnels burrowed deep into the earth, cool by day and insulated from the bitter cold of the night. Water was gathered by vast dew-traps in the surrounding sands, and food was gathered from wide areas and brought swiftly to the cities by the foraging teams.
The desert-runner will spend some time here. The hivers eat only plants, while he eats only smaller animals, so they will not conflict with each other. The moisture that is generated in and around a hive and the food stored within attract all kinds of insects, reptiles and smaller mammals which the desert-runner will hunt, while the hivers, with completely different nutritional requirements, will tolerate his presence.
By 5 million years (the 50020th Century)
The swift hunters, specialized for catching birds, smaller mammals, fish (or even the parasites' hosts), may wonder about the movements in the night skies above them; but they have not the wit to imagine that these events could possibly have any effect on them.
The coniferous forest is black and silent in the night. Hunters lie huddled, asleep. The trees jut up black spikes into the sparkling sky - the sky in which there are now, for the first time in 5 million years, slowly-moving particles of light. Overhead a star, one of the new moving ones, is glowing brighter than the rest. It expands and descends in a gentle arc across the sky, stringing behind it a fading trail of glowing mist. A shock of thunder eventually sweeps across the surface of the land beneath its path, rousing the birds from their trees, and shaking awake the startled hunters on the ground. The glowing descent is now accompanied by blasts of fire as its course is altered, and through the dazzling incandescence can be seen the vague shape of some kind of vessel. It slows, and directly beneath it a descending waft of hot air becomes a searing blast that incinerates trees and undergrowth in a spreading circle. The vessel sinks into the boil of smoke and flame that is produced, and very gently it touches the ground.
Earth's long period of innocence is over.