Humanity turned out to be the most warring, violent, illogical, irrational, and formidable species ever to exist. We all know the legends; small pink parasites operating the brains of vast machines of death, consuming sapient creatures for sustenance and infesting every habitable world they find. Creatures of excess consumption and waste so great that they only entered the Galaxy out of starvation. Worse than anything, and the fundamental condemnation of the species, was that they were completely aware of everything horrible about themselves, and were seemingly proud of it. Their very entertainment was nothing but recordings of violence and tragedy, and they found comedy in the misfortune of anything which seemed unlike themselves. Their selfishness was unique among species, with their entire social and technological structure built around the concept of each human trying to vie for power and dominance.
In other words, a bunch of complete dicks.
Rule 334 of the ICW says "If you can't win a discussion just call someone a Human until they apologize."
Now, I'm writing the story of their rise and fall within the Galaxy partially as a condemnation, but also so that the young citizens of Plern can be wary in case a threat like them arises in the future. I am not, as I have been accused of in the past, a Terran apologist. I do not forgive their actions or their existence; but I feel that to understand them we must understand why they occurred.
Humanity of course had been monitored during its evolutionary process as soon as class 1 sapient emergence was observed: Dana Attuna was in a protective blind on CIT 13.760.025.04 when he first observed this emergence: Several distant ancestors of humans were sitting in a circle masturbating as they typically did, when one of these creatures stopped, looked up at the sky, and paused for one second as if to say "I wonder why I masturbate all day?". Attuna writes in his account:
Gradually the appendage of the smallest one slowed. She pulled her appendage out of her rear end, and her eyebrows changed shape. She looked left and right, then slowly tilted her head back, looked up at the sky, and opened her mouth. One can only suppose she was experiencing, for the first time as a species, a sense of wonder, but as a scientist such suppositions are inappropriate. When the others noticed her behavior, they all looked up at once and stopped masturbating. They stared in unison at the sky for what seemed like a very long time. Then the big one hit the little one with a rock and they all ate her.
Attempts had been made over the eons to shape, slow, and mold their cultural development and to try to encourage peaceful ways. For example: Zzzrill Cra'ven of the Doxian delegation taught the humans about how to stop seeking sapient death for sustenance, but they simply made sapient species their captors, fed on them, and occasionally attempted to mate with them out of boredom. The Doxians never returned after this failure, but the Forthians, ever the gentle caretakers, took up the mantle. Korrl of Forth lived with them for many years teaching a philosophy of acceptance and letting go of desire. Unfortunately a village metalworker discovered that Korrrrl was affecting his profits, so he fed Korrrrl a poisonous mushroom which caused him to vomit for 3 days and then die. Still, Korrrrl made an impact, and things got better for a while until a faction of humans called Politicians dominated the peaceful by not being peaceful. Korrrrrrrrrrrrl, Korrrrl's descendant, took up the cause, and lived with them for 33 orbital rotations. This time he tried to condemn the Politicians and provide a philosophy of forgiveness and meekness. He accumulated a significant following of peaceful humans and seemed to be making significant strides until local Politicians found him, beat him for several hours, hung him from his own limbs, and buried him under a large rock. They then suggested he be ceremonially devoured weekly for eternity as a lesson for others. I know. Total dicks. One last attempt to improve them was attempted one last time by yet another Forthian descendant, Korrrrrrrrrrrrrrrrl. This time he appeared as something called a Dentist*. Korrrrrrrrrrrrrrrrl snuck in a Korthian Truth Elixir into the bloodstream of the human, who was then shown the truth of the universe. This human began to catalog in detail all of the best lessons of the Korthian philosophy, and again, a lot of peaceful humans began to organize around him. Unfortunately, this human only used the knowledge he gained to make money tax-free, hang out with famous humans, and have orgies on a boat. Terra was written off as a doomed society, with only unmanned drones allowed to make visitations.
Now that we understand a bit of what we are dealing with, let's flash forward in time a bit. Shortly after humans had first travelled outside the orbit of their planet (circa CIT 13.772.990.004) Michio Kaku, a "futurist", had made the supposition that interstellar species would likely be evolved from predators. Throughout the evolutionary process which led to Human dominance of Terran civilization, predators typically had larger brains and more physical capability than prey. Humans, despite being physically fragile, developed oversized brains which allowed them to become the apex predators of the planet. Humans would dominate and subjugate all other species, as they had developed a tremendous brain capable of infinitely complex technological creations (in their estimation). The solipsistic assumption, according to Kaku, was that a similar evolutionary process would exist on other planets. The assumption was that anyone else intelligent in the universe would necessarily want to eat and subjugate humans, and would therefore need to be subjugated themselves for the good of humanity.**
Around the same time, a human named Robin Hanson provided the argument that the reason humanity had yet to meet any other civilizations was that there must be some Great Filter, some as-yet-unsforeseen thing which would prevent a species from travelling interstellar space and reaching out to one another. Over time, as their technological progress developed, several hypothesis for what this great Filter could be were presented: Species collapse from geological events, mismanaging waste products, asteroid collision, etc. The wisest of the humans suggested that the Great Filter could be a fault of humanity itself; war using subatomic weaponry, singularity generators, or something called "the comments section" were frequently decried as the worst inventions on the planet.
The notion that nobody wants to hang out with assholes simply never occurred to them; so they ventured forth into space looking for a fight which nobody wanted.
....
**See Terran morality play "The Twilight Zone: How to Serve Man"