Evolution

When they had gathered, the adult mouse-raptors turned, opened their throats, and set up a kind of synchronized wailing. In response, a herd of another kind of animal came lumbering toward the water.

These were big creatures, as big as the goat-elephants. Nervously they huddled together, querulously jostling. But even as they stumbled toward the water, under the apparent guidance of the mouse-raptors, they cropped hastily at the grass under their feet.

Their bodies were coated with sparse fur. Their heads were crested, their skulls shaped to allow anchorage for the tremendous cheek muscles that worked their immense lower jaws: Their heads looked rather like those of robust pithecines, in fact. Their ears, plastered back over their massive skulls, were huge and veined, great radiator fins designed to extract waste heat from their huge bodies. Though their hind legs were massive, enabling them to support their weight, they had the peculiar wrong-way-bending look of the rabbit-gazelles: legs meant for fleeing.

These animals were ugly, elephantine. But they had not descended from goat or pig. They had forward-looking eyes under heavy browridges, huge dark eyes that peered at the world, baffled and fearful. They walked on all fours, but they supported themselves on the folded knuckles of their hands, a posture that had once been called knuckle-walking.

Like Remembrance, their ancestors had once been human.

Remembrance waited until the big dull animals had settled to their drinking, jostling querulously, their ears spreading in the cooling air of the afternoon. Then she crept away.

It had taken millions of years for the great rebound of life to be completed.

Today, to the north of Remembrance’s tropical forest, a great band of temperate woodland and grassland marched around the Earth, stretching from Europe-Africa across Asia to North America. Here more rabbit types browsed the cool foliage, while things like hedgehogs and pigs worked the undergrowth. In the trees there were birds and squirrels — and many, many bats. This diverse group of mammals had continued to proliferate and diverge, and now there were some nocturnal flyers who had lost their eyes altogether, others who had learned to compete with the birds for the richer pickings of the day.

Further north still, coniferous forests grew, evergreen trees whose spiky leaves were always ready to take advantage of the sun’s thin ration of light. Browsing animals lived on the young twigs and needles in the summer, and on bark, mosses, and lichen the rest of the year. Many of them were goats. Especially common were the hadrosaur-like duckbill forms. Their predators included the ubiquitous mice and rats — but there were also carnivorous squirrels and huge birds of prey that seemed to be trying to emulate the pterosaurs of the oxygen-rich Cretaceous skies.

On the northern fringes of the continents a belt of tundra had formed. Here the descendants of pigs and goats cropped the thin foliage of summer, and huddled together to endure the winter. Like the vanished mammoths, some of these creatures had grown huge, the better to retain their warmth, until they were great round boulders of flesh. On the tundra the predatory rats had grown their incisors into huge stabbing instruments, the better to penetrate those thick layers of fur and fat. They looked something like the saber-toothed cats of earlier times. There were even populations of migrant bats who had learned to subsist on the vast swarms of insects that formed during the brief tundra spring.

None of these new species, of course, would ever bear a human name.

There was one key difference in this latest recovery of life, compared to its last great trauma after Chicxulub. The rodents had not evolved until some ten million years after the comet impact. This time, though, when the days of recovery came, the rodents were everywhere.

Rodents were formidable competitors. They were born with incisors ready to gnaw. These great teeth were deep-rooted in powerful jaws: Once rats had been able to gnaw through concrete. Their teeth enabled them to eat food hard and tough enough to be inaccessible to other mammals. But the rodents’ ability to proliferate and adapt was more fundamental. Rodents lived fast and bred young. Even among the giant species like the rat-cheetahs, females had short gestation times and produced large litters. Many of those kits would die, but every one of those dead babies was raw material for the relentless processes of adaptation and selection.

Given empty spaces to fill, the rodents evolved quickly. In the grand recovery after the disappearance of man, the rodents had been the big winners. By now, on land at least, Earth could be described as a kingdom of rats.

All this had left little room for the descendants of humans.