The Last Life on EarthbyPoissonSurLaLune©
We sit together, the mountain and I,
until only the mountain remains.
-Li Bai, trans. by Sam Hamill
The last living thing on Earth sat beneath the bloated red sun, using the energy of the dim rays to turn to the raw elements of its habitat into useful tools for its continued existence. DNA coded for RNA which was turned into proteins, much as it had for billions of years.
If a person had been on the beach, looking at the shallow pool where life had persisted against all odds after each and every other organism had blinked out of existence they would not have seen the small thing, last of it's kind in the truest possible sense of the phrase. Had this non-existent person found and studied it they would have placed it in the kingdom Monera, a distant descendant of the bacteria humanity had once been shocked to discover living virtually everywhere.
Of course, the last ancestor of humanity on the planet had perished long before this non-nucleated cell had earned it's lofty title by outlasting its sibling, spawned from the same mother bacteria. The complexity that had once let the human species marvel at its own achievement, ponder its future, and dream of a time when it could transcend its physical limitations and become something eternal had been the same complexity that made it unfit to adapt to the radical new conditions of the world.
The bacteria could not think; it could not ponder; it could not even understand that it was a bacteria, somehow separate and special from the the barren rocks that surrounded it. The processes of life in the bacteria were not maintained by a will that sought to survive and feared the end. They happened because chemical laws dictated that they happen.
As the environment changed incomprehensible numbers of the bacteria's relatives had died, but among that eternally perishing mass the bacteria's ancestors had always had the slight mutation necessary to stay ahead of the cruelly grinding environment. Some were in plasmids that were transferred among the group, others passed on through cell division. As one population quietly slid into the eternal night it made room for more fit organisms to spread and conquer.
Life was flexible, but it was not infinitely so. The world turned and changed, the star that had been the lifeline for every organism aged. It was a long fight, played across the eons with none of the participants able to fully comprehend its sweep and stakes, but it was a futile one.
The bacteria's parent cell had been one of the few things left on Earth which "tried" - to use the anthropomorphic term - to create offspring, to pass something of itself into the future. It had succeeded, accumulating enough resources to cleave itself into two bacteria.
One of those bacteria had run out of nutrients. The intricate process of life had ground to a halt and it had become a lump of carbon and phosphates and few other elements, arrayed in such a way that if there had been a mind to study them it would deduce that the lump was a vestige of a living thing. Then that lump had decayed and been consumed by its sister cell to fuel the last gasp of a dying world.
Billions of years ago there must have been one cell that started it all, dividing and dividing, its progeny slurping up the readily available elemental fuel. Its descendants had mixed and merged, pumping oxygen into the air, remaking the whole world in their image. When minds evolved that could examine themselves and their world, they saw the traces of this "descent of man" in the shared elegant functions of life. The way that tRNA was part of a universal code, or how the double helix protected itself. They had also looked out to the stars, dreaming of what was out there; perhaps they would find sister races in the empty vastness, perhaps settle new worlds and mold them as that first cell's children had molded this one.
Those minds had long since passed from this world. Maybe they were out there in space, having found new, better homes. Or maybe they had only managed to touch the closest of the celestial bodies and could make no purchase on them so when the last thinking being on the planet had expired, so had the last thinking being from Earth in universe. It really didn't make any difference to the bacteria.
The bacteria lacked that kind of mind. The kind that would have made it fear as it soaked up and processed fewer and fewer resources, losing its ability to maintain homeostasis. It felt no dread as it became apparent that it would not be like its parent cell. It would not split, it would not continue.
And when the functions of life stopped, there was no consciousness to regret that a thing of beauty had passed forever from the universe.