Prior to becoming Mobius, the planet Earth's dominant species was Homo sapiens (a.k.a. modern humans). During Earth's 21st century, the scientist Ivan Kintobor provoked the alien species known as the Xorda by capturing their emissary and dissecting it. As a result, the Xorda bombarded the planet with Gene Bombs, which were supposed to wipe out the human race and maintain the rest of the planet's environment as it was at the time. However, the Gene Bombs instead de-evolved some of the human population, creating Overlanders. (StH: #125, #148)