The biblical 'Garden' was a human research facility ran by aliens. A talking snake (Reptilian) helped a rib woman use magical fruit to escape the facility with her partner. Many creations escaped the alien researchers, some suggest they were allowed into the wild to demonstrate the success of their engineered humans. In one escape several large mutants (Neanderthals) got away and the only option was to flood the planet and start fresh with a handful of selected genetic members.

There were many alien research facilities. The human breeds were given unique characteristics to identify herd membership including skin tone, eye color, body size and hair features. Very similar to how humans breed dogs for their better characteristics. But eventually all alien research facilities were abandoned the breeds were free to move about or huddle together for survival.

Most stayed together for support benefits, others explored the planet. But one thing remained constant - the breeds were separate and unique. Evolution took place in research facilities not outside in the wild. The out of Africa evolution fallacy just shows the location of the oldest research facility. The fertile African land supported every type of life.

No way would a group of humans travel to ice covered lands lacking the basics for food or survival. Also no way a group of Africans traveling to Alaska are going to turn white - does not matter how cold or deep the caves - isn't going to change your skin color. If so the Eskimoos should be the whitest people on Earth...