The City of Cyan is ahead of its time. Chemoautotrophy is all good and well, but these tropical bacteria have moved on from stinking sulfur and tangy ferrous iron. Now they eat sunlight, and it is simply divine. They turn the light into glucose in their factories; they put that into their engines. Their cilia motors whir through the water with newfound energy, wagging like pigs’ tails as they revel in the novelty of the sugar high, the sugar rush.

A futuristic floating city, a spherical city one centimeter across and hundreds of millions strong, held together by communal mucus. A planet in its own right, bobbing in ancient waters. They have nothing like eyes, but they are sensitive to the visible light that sustains them. They sunbathe off the coast of Vaalbara or Ur or Kenorland—the island supercontinents of their time—basking in the warmth of the photon shower, of every wavelength between red and indigo. They taste the rainbow.

Chlorophyll: They have gone green. They have also gone the reds and pinks of carotene and the blue-greens of phycocyanin. Oscilla turns the water red as she blooms like a young maiden; red as the first-plague Nile or the Sea that would part soon after, though neither event will occur for another three billion years. Spirulina, high in protein, who will give African flamingos their color and find herself in powdered form on store shelves, today blushes brazenly only for herself. And though she will be known as “swimmer’s itch,” Lyngbya swims in the early ocean free from ridicule. It is a colorful, cosmopolitan community, a literally enlightened place embracing diversity and progress. The City of Cyan is ahead of its time.

See the light they enjoin their sisters, their neighbors. Light is life. This is the future.

They are simple creatures but they have mind as well as body, ancestral memories encoded on miles of tangled nucleic acid strands like the folds of gray matter. They have souls. And individuality, quirks, original ideas that pop up in the DNA like flashes of inspiration, visits from the muse of mutation. That’s how the future began: a contagious epiphany. Ideas spread organically through the City of Cyan, along the chemical grapevine. Photosynthesis is a meme.

Sometimes things are said, thoughts are shared. A penny for your thoughts, whispers Spirulina with her most seductive signaling protein. A piece of your mind. Membranes are broken, pilus inserted, temporary physical connections made. Plasmids—the mind-pieces, the soul-strands—are given or taken, new ways of doing and being exchanged in asymmetric fucks. Not quite love-making, but certainly earth-shaking. Photosynthesis is a sexually transmitted disease.

Photosynthesis is inefficient. There is waste. There is exhaust. The citizens of Cyan know nothing of sight or sound, but they can smell the change in the air, in the water. This is how the future begins to end. With a shift in chemical concentrations, a stench like ozone and oxides, like pollution and rust. The end begins when flatulence becomes more than mere embarrassment.

Oscilla looks at herself, at the handful of oxygen atoms she exhales with each breath, hardly a hiccough, barely a bubble, and wonders how she can change the world by merely breathing. But others look within themselves for the records of division. They extrapolate. You divide, then each of your daughters divides, while I am doing the same, and her as well. This has been going on and will continue to go on. They get a glimpse of the exponential. Can they hold such staggering numbers in their little minds? Can they understand the global impact of future generations? Hundreds of trillions of cyanobacteria cover the Earth. Earth? Can they comprehend that this planet is finite, a little ball itself, like their city?

Their oxygen footprint is large and they realize too late that this is not sustainable. Not at the level of the quorum, not the colony, not the sprawling bacterial mat. The City of Cyan belches up clouds of unnatural gas which flow down into valleys and turn the stone red with rust. Until the iron is saturated and the pollution accumulates in the air. Slowly, all of the other species are gassed in a cage of gravity. Our cousins are dying say the citizens of Cyan. We will be alone.

Breathe in. Breathe out. Divide. Repeat. Until you suffocate the world.

Later, extravagant metropolises far larger than Cyan that nonetheless think as one cell will breathe in the noxious vapor as if it is light and life, will hijack its toxic energy, will come to depend on its poisonous polarity. New ways of doing and being in an altered atmosphere. Yet today Lyngbya cannot predict this, nor should she. Today there is mourning and mass extinction. Today Oscilla turns the water blood-red as if for the last time, bleeding out for her suffocated cousins, though no one is equipped to view her gesture. Today there is guilt and shame and shivering. It is cold.

An ice age settles into place. The cells of Cyan—the souls of Cyan—begin to die as well. Snowball Earth. Delicate crystal planet spinning through space.

What have we done?