Speculative Apes of April: Underground

No one remembered what caused the nuclear war that, for all intents and purposes, wiped out humanity. Mostly because, once it was over, there was no one left to remember it. And millions of years later, when the radiation dissipated and life on Earth finally regained its former diversity, humanity was seemingly nowhere to be seen. Seemingly, that is. In truth, one last vestige of humanity remains-- the last primates on the planet. Orycteranthropus ultimus is almost unrecognizable as a hominid, but therein lies a tale. When the nuclear war began, a small number of humans-- most of them billionaires, corporate executives, and other such over-privileged types-- took shelter deep underground in fortified shelters. But as days turned to weeks, weeks to months, and months to years, hope to return to the surface seemed to die away. Most of them either died or went insane, but a few survived, often resorting to horrific measures to do so. In this underground environment, they set up a subterranean society, but it did not last long before the cold, unfeeling forces of natural selection set in. 

The scarce resources of these underground caverns worked against the evolution of intelligence, from an evolutionary perspective, and within a relatively short time, these underground people had lost much of the knowledge of their ancestors. They had no desire to return above ground, and as time wore on, their humanity slowly evolved away. Now, fifteen million years later, we see the end result of this change. Orycteranthropus is a burrowing mammal about the size of a marmot, with sharp claws evolved from its ancestors' fingernails. It feeds on roots and insects, and its intelligence is negligible. This creature is all that remains of the once-mighty Homo sapiens, a species that dominated the world and brought about its own ruin in doing so.