The "isolated by glaciers" thesis is also applied to the division of Caucasions into three or four major groups, e.g. Caucasions, Sinatics (Chinese and other East Asians), Jomon (Ainu). There's probably enough genetic differences between the Saami and all the others to classify them as yet a 5th major division.
Speaking of some serious differences, did you notice that when that Norwegian rock freighter sank a couple of weeks back virtually all the Philipino crewmen died while the Norwegian, Friesian and German crewmen lived (note, the Norwegian captain seems to have died due to a serious body blow when the bridge area hit the water as the ship capsized). They've studied Korean pearl divers to see if they have inherited physiologic differences, but they don't. Seems to me somebody ought to check out these North Sea/Arctic Ocean types!
Then there's the virtual absence of inherited seafood allergy among the Norwegians in general - otherwise 45%+ of human beings have such an allergy.