It is possible that "Caucasian" traits are the result of an extraterrestrial humanoid race crashing into the North Pole after the end of our last Ice Age and reproducing (possible due to both species being results of protohuman seeding i.e. close enough genes to make offspring) with the native inhabitants.
Prehistoric fossils have suggested the existence of "Nordic" looking people in North America. ( http://en.wikipedia.org/wiki/Spirit_Cave_mummy )
Also, this: http://en.wikipedia.org/wiki/Chachapoyas_culture
A possible explanation for this is that the passengers on the downed extraterrestrial spaceship that crashed into the North Pole went southwards into both hemispheres.Accounts such as that of Cieza de León indicate that the Chachapoyas had lighter skin than other South American peoples and blond hair. This poses an enduring mystery for scholars of the region as to their ultimate origin.
Most "white" languages are far more similar to each other than "asian" languages or "african" ones. Again, this suggests a linguistic "common ancestor" of sorts; i.e. an extraterrestrial race.
Also this: http://en.wikipedia.org/wiki/Tarim_mummies
Are you seeing what I'm seeing?
I highly doubt this is true, but it's certainly a possibility.