The earth has gone through countless changes in its history. Antarctica at one time was not covered with ice, and could have been home to ancient humans.
As we develop new methods for uncovering the ice, we are beginning to see the possibilities that lay below. Mainstream ideology puts forward the "Out of Africa" theory, which tracks humans originating in Africa and spreading out by land across the world.
However, genetic research is finding evidence that makes our story far more complex. One of these findings is the discovery of the Denisovan people of Siberia, which reveals an entirely new, intelligent human subspecies (first discovered in 2008).
It is findings like this, that cause us to have to rewrite human history.