Evolution

Today, the start of the females’ simultaneous estrus, the air was full of an invisible pheromone cloud, and there were males everywhere, helplessly drawn, erections poking out of their fur. Every male had prepared since the return of the sun, feeding to build up his strength, practicing spectacular tree swings and engaging in mock battles: They had been like athletes preparing for a contest. It was impossible for the Emperor to keep them all away, and there was intense competition. Today the hierarchy of males was stressed to the point of collapse.

The stress on the females would come later, during pregnancy and nursing, when the fast-growing fetus or newborn pup demanded the mother find a stream of high-energy food — and she must eat well at a time when almost every other adult female was nursing too. It was the heavy cost of reproduction that had led to the general dominance of females over males, and it was the reason why the females always got the best of the food.

It was the same all over the forest. Every notharctus troop was hitting its brief mating season simultaneously, the timing dictated by the invisible chemical scents that permeated the air for kilometers around. For today and tomorrow, the forest was filled with primate lust: a tremendous clamor of battling males, pheromone-laden females, and frantically thrusting hips.

Noth, pursuing another young male he thought of as Rival, hurled himself through a loose stand of conifers. He swung one-armed on spindly branches. On each dip the earth tipped up like a vast bowl, dead leaves and new green ferns and the dull forms of snuffling ground feeders fleeing under him.

He approached a gap between two tall trees. On the far side he saw Rival, standing upright, genitals pinkly visible, rubbing his scent markers on the bark. Rival barked a contemptuous challenge.

Without hesitating, Noth took a final huge swing. The branch flexed and hurled him on a smooth parabola high into the air. For a few heartbeats he flew, tail held high, hands and feet held out before him ready to grasp.

His head was filled with the stink of estrus. He had had an erection since he had woken this morning. Even now, as he sailed from tree to tree, his penis stuck out before him, pink and solid. He had yet to succeed in battling his way through the crowding males to get to a receptive female, and he felt as if his belly would burst if he didn’t succeed soon. But even as he was consumed with inchoate lust, still he relished the power of his lithe body as he hurled it through the forest domain for which it was exquisitely adapted.

Noth had never felt so alive.

Noth landed in Rival’s tree, just where he had aimed. He grasped the branches with faultless positioning of his hands and feet. But immediately Rival was on him.

Facing each other they stood upright, their spindly erections poking out. Noth, tail held erect, stalked toward Rival, vigorously rubbing his groin against the tree bark, chattering and barking. Rival responded in kind. It was a ritualized encounter, each of them responding to the other’s movements in a kind of dance: tail waft followed by groin rub, wrist spread provoking a spitting glare.

Soon the air was filled with their angry stink. They came close enough for Noth to feel the tips of the other’s bristling fur, and Rival’s spittle sprayed his face.

Rival was about the same age as Noth, about the same size. He had joined the troop a little earlier than Noth and his sister. To him, Noth had invaded a troop that he had come to regard as "his." Noth and Rival were too similar, like brothers, too close to be anything but enemies.

Rival was marginally bigger and heavier than Noth, and if anything he had done better in the early-season feeding. But Noth’s difficult year had forged an inner toughness, and he stood his ground.

Psychology won out. Rival subsided suddenly, his display collapsing. He turned his back on Noth and, briefly, symbolically, displayed his pink backside in a curt gesture of submission.

Noth hooted, relishing his moment. Briskly he rubbed his wrists over Rival’s back, marking his victory with his scent, and released a stream of urine. Then he let Rival slink away along the branch toward a cluster of berries.

Rival would come to no harm. He would skulk alone in his tree for a time, perhaps feeding, withdrawing for a while from the fray. But his chances of mating were for a few hours reduced. Noth’s urine would make him briefly sterile; it would even reduce his ability to make the special trilling calls used by the males to attract females.

For Noth it was a valid strategy. Today it was impossible for any male, however heroically he tried, to cover all the females. But he could reduce the number of competing males with such sensory intimidation.

With Rival defeated, Noth’s penis throbbed anew; soon he would at last attain the satisfaction he craved. With fast, vigorous swings he hurled himself through the branches, across the forest toward the place the females clustered.