An alternative theory is that only blondes are dumb enough to stay in northern Europe. bohm:
yeah, and from the Orkneys to the Alps, the Caucasians created a fantastic Civilisation that is responsible for most of the advances we have seen (with Chinese, others working in the tandem, unknown).
Now, the others, having basked in the sun, tanning in the process, are streaming into the northern wastelands to take over. Dark surfaces , skin, radiate heat more efficiently, so bundle up, and over millionenennia, will that lighten the skin? Try cross breeding instead.