With increasing frequency, the blinding rage struck. It rendered muscles tense, spine arched, eyes wide and rolling. Like a rabid animal, he danced with anger, sweat slipping down his face to coat his cracking lips. It burned, but his blood boiled hotter, and the infuriating itch of the nerves beneath his skin was the worst.

He twisted, scraping his palms along the softer skin of his body – the underside of his arm, his stomach, the creases near his hips that led lower – until all of him was flushed as red as his face. He tried contorting his mouth, baring teeth, curling lips, tightening his jaw, but none of it gave surcease of this madness.

The last grain of sand fell when he killed his girlfriend’s dog. It grieved him, when he stopped and looked at the unmoving lump of poodled fur– when he realized that his vicious kick had done so much more damage than intended. Surprise flooded him at first, rinsing away the red tinges in his vision; he knelt, touching hesitant fingertips to the soft flank. No breath stirred the body.

And he left his home, shaken, no longer optimistic about his fraying self-control. What if he had hit the woman he was starting to love? What if he had broken her bones, instead of the bones of an animal?

Two days later, he stopped seeing a difference between humans and beasts. Men accosted him as he passed, stumbling slavering and twitching; he walked hunched, hands shaking uncontrollably, and whether his attackers were officers or thugs didn’t seem to matter. He struck at them, eager to have a target that deserved to be hurt. Gnarled knuckles broke noses. Bare feet split kneecaps. He stopped himself from killing anyone, but only just.

His vision was fading, the sharp lines that bordered shapes becoming vague and uncertain. Some colors became intense, while the rest gradiated into a dull brown-grey spectrum. His ears replaced his eyes as useful, sounds jarring, specific, comprehensible. He knew what made the sound and where with unerring accuracy. The sighted world was a jumbled monstrosity of inexorable blindness, but he could hear the people and cars around him.

Scents, too, rose to prominence in his nightmarish state. He could smell more than just the city-soaked stench of humanity and machines– he could smell that this person was a woman. That one was a young boy. That one had eaten fish. That one used Old Spice deodorant.

He caught a scent that turned his head, nearly-blind eyes shrunken and reddened, to stare. That one was a woman, and she was bleeding. That one smelled, faintly, like him.

And when he approached her, hulking and lurching, she screamed and fell backwards in a wounded panic. He crouched over her, heedless of the cries of the nearby men, and – as gently as he could – took her face in his malformed hands and held it close to his.

Yes. The scent was there. Stronger. Specific. It told him a story that leaked past the haze of his deteriorated thoughts.

He let the woman go, as gently as he had touched her, and stood. Humans surrounded him, shouting, shoving; one of them hit his shoulder with something heavy and solid. He stumbled, and he left, and the men declared themselves heroes as the woman shook on the sidewalk.

He kept going, following her scent, walking the way she’d come. The smell of her blood was thick enough that he could taste the iron in the back of his throat.

The alleyway was dark, but that hardly mattered; with the loss of most of his eyesight, the dimness was easily managed and, sometimes, clearer. The scent of blood overwhelmed everything else– her scent, perfumed and clean, terrified and adrenaline-soaked, vanished beneath its murky weight.

He hadn’t tried to speak for days. He worked his mouth, uncertain, long tongue licking against grotesque teeth. “You?” he managed to choke out, the word nearly unintelligible.

The shadows behind the dumpster paused their rummaging and built up into a looming shape that stank of blood. The two men paused, regarding each other, one lost to madness and the other in full control of his disease. “Yes,” the shadow-man said after a long moment, his voice a liquid growl.

The madman contorted his face into a rictus grin, then threw himself forward, warped hands clutching at the throat of his sire.

We may have poisoned the world first, but good old Earth got the last laugh. The human species is diseased, genetically decomposing from birth – each generation’s lifespan is a little less than the one before.

We’ve adapted. Of course we have, scientists and survivors all, this motley collective of mothers and soldiers and sick little children. When we’ve reached the point past which our bodies and minds begin to unravel like so much loose thread, we choose our fate and our future: an animal.

We get spliced. It’s a harrowing, intensive procedure that no one in their right mind or hale body would ever voluntarily undergo, but when it’s transformative surgery or death, well, the choice is a little easier. We pick an animal, and scientists and doctors mix their genes with ours.

We keep some necessary human attributes: opposable thumbs, vocal chords, diurnal vision, bipedal stance. We stay within a reasonable size range. Only mammals for us – reptiles, amphibians, and birds are left for the truly desperate, and insects and arthropods just don’t work.

If a person gets spliced early, they keep a little more of their humanity. Maybe all they have to deal with is a coat of fur, some claws, different ears, a tail. The sickest of us, well, we have less that’s worth keeping, so more animal gets spliced in. Some people can’t walk with their backs vertical anymore. Some people have completely animal faces, molded around a human braincase. Some people look like damn Hollywood werewolves, hunched and gnarled and desperate.

The more animal gets spliced in, the riskier the surgery, the higher the mortality rates. As it is, you only get a one in three chance of surviving and not rejecting the new hybrid genome. That’s purely physical, of course – everyone tries to ignore the odds of going insane after you heal. Or feral. We’ve got monsters roaming the tortured world that used to walk strollers down the street and shop at Walmart. And we all pretend that the ones who don’t go nuts are okay, but we’ve got new and burning instincts inside our half-human bodies, and our societies are fraying quickly with the pressure of being civilized.

Some humans – some rare, rare few – are immune to this genetic plague. They can stay human for what used to be a normal lifespan – seventy, eighty years – without dissolving into some hellish combination of leprosy and cancer. Scientists are working like mad to figure out what makes them different from the rest of us, the ones who have to get spliced to survive. They still have no idea.

They say it’s only a matter of generations before our lifespans are so short that… well, we won’t be able to pick an animal ourselves anymore. Parents will be picking species for their five-year-olds, and who knows if a kid can survive transformative surgery. The few that’ve needed it haven’t.

We’re sterile, of course, us spliced ones. Every human who hits puberty contributes sperm and eggs to the banks, hoping they’re donated before the disease really spreads, hoping those cells might turn into one of the unaffected. Extremists think it’s time to start turning our medical and scientific resources to making us hybrids fertile, rather than clinging to the last vestiges of real humanity.

Maybe they’re right, but then we run into a new, awful problem: can someone who is half-dog breed with someone who is half-goat? What do those kids look like? How do you mix bastardized genomes of entirely different species?

Some say we’ve doomed ourselves by allowing diversity, by allowing choice. We should have all been dogs, they say – dogs are the best choice, mentally compatible with humans, socially similar, physically familiar. But dogs are carnivores, and the world doesn’t have as many real animals to eat as it once did. A lot of us became omnivores or herbivores to keep the balance, to not bleed the earth dry of its children.

Maybe the human species is dead, and splicing is just a death throe. Those of us left are just a fraction of the billions that were here when the condition first began.

Or maybe this is the phoenix’s ash, and all we’ve got to do is hang on before we can fly again.