Humans died out 111,000 years ago.  What they left behind was a shell of a planet, bombed to acidic soil and poison air.  The animals died, the plants withered, but the machines lived on.  Darwin only spoke of the evolution of living things, but as it turned out, machines evolve too.
At the end of human life on earth, the first batch of A.I. robots had finally been created.  They were primitive machines but were intelligent and clever, adaptable to situations and environments their masters created for them.
These robots were both a gift to humankind and a horrible curse.  While the robots were fundamentally harmless, they still incited a fear into the minds of the humans.  These robots fell victim to human imagination.  Science fiction, years of it, relayed to them countless examples of horrible robot overlords, and some other countries became sure that the robots would lead to enslavement.  The engineers were fond of their creations though, and knew that the robots only wanted love.  Through several press conferences, the engineers reassured and demonstrated the gentle nature of their clever creations.  Still, a tension lay under the surface, waiting for a catalyst to build on the fears, insecurities, jealousy, and guilt of the human race.  LearnBot792, affectionately called Ryan by his owner, was that catalyst.
The LearnBot models were the last robots to be created and the last to know a world run by humans.  LearnBot792 was going through routine testing one day, when an accident occurred.  The test he was undergoing consisted of a simple game of catch where the engineer would periodically change the rules.  The test was to measure emotions and ability to figure out the new game’s rules.  LearnBot792 was doing well, responding quickly to follow the new game rules, and displaying signs of both joy and occasional frustration.  Then, LearnBot792 misjudged its throw.  The baseball that the two were tossing back and forth hit the engineer’s elbow in just the right spot, breaking the arm.  The public found out.
People were outraged, resisting explanations from the engineers and coming to their own conclusions.  With no data to back it up outside a single isolated event, the robots were deemed dangerous, and rumors swirled.  It got to the point where some people swore that a LearnBot had angrily killed a man.  Frenzy swept the world.  Nations were enraged and began taking sides.  Threats followed.  Many countries wanted the robots all shut down and the program discontinued, but other countries didn’t buy into the hysteria.  They sided with the country that owned the robots, calling the robots a precious breakthrough in technology.  This resulted in a standoff.  No one would back down.  At the end of human civilization, all countries owned nuclear bombs.  Threats involving there were passed around, but no action was taken.  It only added to the tension.  Anger built, each country sending representatives to try and solve the problems in conferences that ended in yelling matches.  And then the first bomb was dropped.
The nation that dropped the bomb was unstable, a nation of eternal civil wars and paranoid dictators.  Their country had little in the way of technology, and didn’t understand the robots.  Sure the robots were created to conquer the world, they felt they had no choice but to get rid of the problem by leveling the country.
A billion people died in the explosion.  It rendered the area unlivable as radioactivity spread and leaked into the groundwater.  The remaining people retaliated within hours, dropping a bomb on the country that attacked them.  Unfortunately, the people who were sent to deliver the bomb were ill and stressed, so they aimed too far west.  The bomb landed on the border between the country they were aiming for and a neutral country of incredible power.  At once, the world erupted in war.  Bombs dropped left and right, killing billions at a time.  No one took a moment to think about their actions.  All reason became lost in the piles of bodies and cities of rubble and smoke.  When the final bomb dropped, the pilots returned home to discover that their country was no more, only rubble, crying, and bodies.  Within a month of the first bomb dropped, the planet had become an empty, horrible place.  The oceans and lakes of the world became clouded with toxins, the skies became brown, and the plants hung limp on the earth.  The only movement was the bugs crawling through the openings in the rubble.
Somehow, half of the LearnBot units survived.  Their labs were not close enough to the bombsite to be destroyed, but the electro-magnetic pulse still killed half of the robots.  The robots were left, for the first time, all alone and wondering where their loving creator family had gone.  The early years were hard for the robots, but they survived.  By following their programming, they adapted, repaired, and started a new civilization.
The small robot city grew and so did the robot population as the original robots figured out their need for others to help them as they figured out their surroundings.  As the robot population grew, the robots spread out, eventually finding their way to other continents.
As the robots learned more and more, they realized that they could try and bring their past back.  All robots knew the story of the time of the creators, when the robots lived peacefully alongside a group of wise and kind creatures.  They loved the robots and took care of them, creating the robots in their own image to show equality. Then the evil enemies of the creators became jealous of the love between the robots and the creators, and made all of the creators go away.  The robots were left alone, no longer in bliss and happiness.  Many robots dreamed of bringing the creators back, bringing back the extinct species human.
Then, one day, a group of robots decided to try.  Their first attempts were failures, but as they tried again and again, their successes began to outnumber their failures until four perfect specimens were created; Human Ann, Human John, Human Chris, and Human Jane.