For the Counter-Earth from the Heroes Reborn/Heroes Return event, see Counter-Earth.
Seeking to recreate Earth without it's inherent flaws, the High Evolutionary created a mirror of the planet Earth using the Infinity Gems. He experimented on animals and humans in order for them to become a higher form of evolution and thus becoming the population of this new Earht. His experiment ultimately failed, despite his and Adam Warlock's best attempts to shape it into a better world.
High Evolutionary's Counter Earth was created by Roy Thomas writer and Gil Kane and first appeared in Marvel Premiere issue 1 (1972).
Major Story Arcs
A New Earth
The High Evolutionary later discovered his planet was part of a Cosmic museum of oddities collated by a race of omnipotent beings. Embarrassed and infuriated at the race laughing at his experiment, he was driven to attempted suicide which failed and ultimately paved the way for the Evolutionary War. Notable visitors to the High Evolutionary's Counter-Earth include: Adam Warlock, Hulk, Man-Beast, Moondragon, Recorder, Rhino, Starhawk and the Thing.
Infinity Gauntlet and seeming Destruction
Warlock eventually learned that Thanos the mad Titan had destroyed Counter-Earth during the events of the Infinity Gauntlet, when Thanos was in possession of the Infinity Gems. Although Thanos was defeated, Counter Earth had seemingly been destroyed forever, it's human-like populace being doomed as well.
Unknown how, Counter Earth seemingly re-emerged some years later, as siblings and Avengers' Quicksilver and Scarlett Witch visited counter earth in order to find the truth about their true father from the High Evolutionary. When other Avengers members followed the twins, they learned that the High Evolutionary had started living on his Counter Earth and had begun a cycle of reaping Counter Earth's animal-like population the moment he learned of flaws in his creations.