I'm curious because I find the Second World War fascinating. The topic of Aryanism/race is so interesting, since it's tied directly to the largest war ever, thanks to the Nazis.
I'm curious about their ideologies such as the race one, especially because since reading on my own I've discovered that the whole blonde-blue-eyed thing is merely a misconception of being Aryan. I also read about the Mediterranean, and Alpine peoples.
I'm just curious if someone can please boil this down and make it a bit more simple to understand, since there's a lot of discussed information on the subject.
What promoted the Nazis to believe and follow these racial ideologies?
I recommend you check out The Mismeasure of Man by Stephen Jay Gould. He delves into all of these different ideologies and it's fascinating stuff.
Long story short: there's no veracity to these ideologies or the methods of measuring people's heads and faces. It's junk science that was dismissed long ago. But it is true that in the very late 19th and early 20th centuries, there was a fad for eugenics. Many supported the idea that you could tell all kinds of things about a person by measuring their head and nose, etc., and that the traits of the parents would be passed down to the children--not just physical traits, but moral and intellectual traits. This fad was strong in the US in the early 20th century, and laws were passed throughout the country declaring that certain people be sterilized against their will. For example, people who had been impoverished for 3 generations, criminals, blacks, and more. It was at this point that laws were passed in many states forbidding marriage between first cousins even though that was a normal, even encouraged, practice earlier. But even as scientists were abandoning such notions as time went on, a young Adolf Hitler, no expert in these areas, seized upon such notions and helped to create an ideology. He was supported by the pre-existing ideology and by others in Germany (and elsewhere) who wrote books supporting those ideals. Germany found fertile ground for those ideologies because the people were rather crushed by war and a destroyed economy. Which doesn't excuse them, but it may indicate their state of mind. Here was a guy saying they'd been cheated out of their just victory, plus they weren't supposed to be the downtrodden, miserable, starving people they were at that time--in fact, they were the greatest people on earth, they had unique qualities that were plain to see, and that no one else had. When the economy recovered from 1924 to 1930 or so, the Nazi party got few votes. But after the depression took hold, the party gained prominence again.
But if the qualities were so plain to see and obvious, they wouldn't need careful measurements to determine if you were Aryan or not. The reason measurements were so important, was that they had the veneer of science and numbers and methodology behind them. Eugenicists had been saying that there were certain appearances that were prone to violence or crime, and Aryan eugenicists piggy-backed their ideas onto those. There's an allure to measurements and testing--makes it seems systematic and impartial, when it's not. Incidentally, while this issue is too large to go into here, not only was there no validity to Aryan notions of racial purity or superiority, but the very idea of race is simply scientifically wrong. There is no clear division between different human groups. Sure, if you took a Swede and a sub-saharan African and compared the, they'd look different. But what they are are extremes of one single group--the human race. The number of genes that control the visible differences between groups is very small, and there is far more variety within each racial group than between two so-called races.