Chapter Two Hundred Twelve: Drought and Adaptation

Volume Six: Spirit-Life in Dahuang — Dao Grace Everlasting

That year, Dahuang suffered its first great drought.

Until then, Dahuang had always been moist. The Primordial Qi released by Pangu's transformation into Heaven and Earth had brought abundant rain; rivers ran full, lakes brimmed deep, and forests spread from valleys to hills. No corner of the land lacked water. The first generation of life had taken shape in precisely such a setting, and they were accustomed to moisture, to the plentiful supply of water and food.

Then the drought came.

No one could say which day it began. The rain simply diminished. First, two weeks without a drop. Then a full month. The sky stretched cloudless from horizon to horizon; the sun beat down from dawn to dusk. The riverbeds shallowed day by day, exposing cracked mudflats on either side. The forest floor piled high with dead leaves, snapping and crunching underfoot like dry bones.

The creatures of the lower reaches felt it first. As the water level dropped, masses of fish were trapped in shrinking pools. The pools contracted by the hour; fish pressed together, and the bodies of the dead floated upon the surface. The waterfowl that fed on them were forced to fly farther and farther afield to find food.

The forest herbivores faced crisis as well. As the soil dried, tender grass grew scarce; low shrubs yellowed and withered. Some insects were the first to fail — their larvae required moist earth to hatch, and the drought desiccated their eggs before they could.

By the third month, the situation had grown worse. A major river ran dry. Its once-lively banks fell silent, leaving only a few gaunt beetles crawling through the cracks in the riverbed stones, hunting for the last traces of damp trapped beneath them.

Creatures without the capacity to adapt died in droves. The surroundings culled them. Dahuang had finally revealed its cruel face. Only those that could survive the drought would earn the right to pass their seed to the next generation.

What was striking was that different kinds chose different responses.

One small rodent learned to burrow deeper underground. Its tunnels, once half a span deep, now reached two full spans down, opening just above the water table. The humidity deep in the earth was far higher than at the surface; the rodent also learned to store succulent tubers in its tunnels as a dry-season water source.

The reptiles along the riverbanks shifted their active hours. Before the drought, they had foraged by day and rested at night. Afterward, the daytime heat grew so fierce that the ground's surface could scorch their bellies — so they changed to feeding at dawn and dusk, spending the midday hours sheltering in rock crevices.

Some birds began to migrate. They flew along the river courses, searching for places where water still remained. Most never returned; they found new dwelling places and settled there. This led to the dispersal of kinds: birds once found only in the lower reaches now spanned the entirety of Dahuang.

Other creatures displayed a startling speed of adaptation. One kind of aquatic algae did not die when its pond dried up — it entered a dormant state. Its outer shell grew extremely hard, resisting heat and desiccation. When the rains returned the following year, these seemingly dead algae revived in the water and reproduced even faster than before the drought.

The great drought lasted an entire year.

When the rains finally came again, the face of Dahuang had changed. Some kinds had vanished; others had emerged from the crucible stronger, more diverse. The rivers recovered their flow; the dried lakes refilled; the forests greened again. But the map of life had been redrawn. Those that had learned to endure drought claimed the advantage, and those that had not were left behind forever in the season of thirst.

In the sky above, Xiwei saw it all. She did not intervene. This was the rhythm of Heaven and Earth itself. The world Pangu had formed had not only given life its Myriad Things — it had also given them the right to shape themselves. Adaptation and elimination, birth and death, flourishing and collapse — these were all ways the world turned.

She was only a beam of light. Her role was to illuminate. It was for life to find its own road.

Of all the stories born of the drought, the most astonishing was the transformation that took place in one small river.

The river was not large, and even before the dry season it had already dwindled to a third of its former volume. The water ran muddy and slow; the exposed riverbed was strewn with dead clamshells and fish bones. But in the deepest pool that remained, one kind of creature was still alive.

It had no name. Let us call it the scale-finned fish.

The scale-finned fish resembled ordinary fish: a flat, elongated body covered in fine scales, a low dorsal fin, and a broad tail fin. But it possessed one distinctive trait: its pectoral fins were thicker and sturdier than those of other fish, and between the fin rays ran cartilaginous supports that gave the fins structure beyond a thin fin membrane — they could bend, and they could brace against the ground.

This was the product of generations of accumulation. Before the drought, this fish had lived in shallow zones where the current ran swift and the riverbed was stony. To keep their bodies steady in the rushing water, individuals whose pectoral fins were slightly thicker and whose tendons were slightly stronger had lived longer, leaving behind more offspring. Generation by generation, the pectoral fins had grown ever sturdier.

But the drought forced that slow accumulation into sudden acceleration.

The pool shrank day by day. Air-breath in the water dwindled; the scale-finned fish often surfaced to gulp air. Deadlier still, the food in the pool was vanishing — aquatic larvae and algae died in droves in the high degrees of heat. Hunger drove the scale-finned fish to attempt something they had never tried before: they began to venture experimentally out of the pool and onto the wet mudflats, hunting for terrestrial insects.

That first generation's attempts were clumsy.

The fish braced their pectoral fins against the mud and dragged their lower bodies forward. Their gills dried out rapidly in the open air; they could only linger at the boundary between water and land, retreating back at any moment. Most of those that tried did not survive more than the time it takes a stick of incense to burn — not killed by predators, but desiccated, or asphyxiated when their gills cracked and failed.

But the individuals with particularly strong pectoral fins, and whose gill structures held marginally better against dryness, survived at a slightly higher rate.

In the second generation, the changes grew more pronounced.

In the second month of drought, a female scale-finned fish laid a clutch of eggs. Their incubation fell exactly on the days when the pool had shrunk to its smallest, and the fry that hatched faced the most barren surroundings any of their kind had ever known. Driven by hunger, those fry born with naturally thicker pectoral fins and quicker movements began to climb out of the water on their own to hunt the small insects along the bank. Their gills had already begun to show a change: the once-delicate gill filaments had become denser and thicker, capable of sustaining respiration in moist air for twice as long as the gills of their kin.

These advantaged fry grew to maturity and produced offspring that inherited those traits.

By the third generation, a strange transformation had appeared.

At the tips of a few scale-finned fish's pectoral fins, beneath that thin layer of skin, minute bone spurs had begun to grow. They were not extensions of the fin rays — they were an entirely new structure, the rudiments of toes. Their shape was still irregular, like five tiny bone buds wrapped in a translucent membrane. This structure was utterly useless for swimming; it might even have increased drag. But when the fish crawled, those bone spurs provided extra grip.

The individuals that possessed them could climb damp mud slopes far better than their kin. They could reach the denser concentrations of insects farther from the pool's edge and secure more abundant food.

The changes did not stop there. Near the back of the gills of some fish, close to the throat, a new cluster of tissue had begun to appear — the primal form of a lung. It could hold only a tiny amount of air, but that was enough to let the fish gulp a breath at the surface and stay submerged twice as long. This had originally been an adaptation to turbid, air-breath-poor water — yet it proved unexpectedly valuable on land: they could use this primitive lung to breathe air-breath from the air, no longer wholly dependent on their gills.

By the fourth generation, some of the scale-finned fish were returning to the water only rarely.

They hid by day in the stone crevices and damp leaf litter of the riverbank and emerged at night to hunt. Their bodies had grown flatter; their pectoral fins were ever stouter; their tails had shortened. Their skins had thickened, their scales hardened, reducing evaporation. Even as their gills receded, that cluster of primitive lung tissue expanded more and more.

They were no longer purely fish. They were something transitional — a bridge between fish and reptile.

When the rains finally returned and the floodwaters refilled the river channel, the descendants of those fish faced a new choice: return to the water, or remain on land? Most returned — the water was, after all, the home of their ancestors. But a portion chose to stay. They moved upstream, entered the marshes, climbed the banks, seeking new ground beside the water where no other fish competed.

Those that remained on land would go on, through numberless subsequent generations, to undergo further transformations. The bone spurs on their feet gradually differentiated into true toes. Their breathing organs completed the shift to lungs. Their skins grew ever thicker — until at last, they transformed into an entirely new kind, capable of independent survival on land.

They were the first backboned creatures to climb onto the land. Their descendants would develop still more forms. The story of Dahuang had gained a new frontier.