The roots of Hitler’s (and Himmler’s) racial policies are derived from a racial philosophy based on popular science of the time, primarily anthropology and genetics. A group of thinkers began to emerge in the late 1900’s who would come to be known as Social Darwinists. This group stretched and corrupted Darwin’s theories of evolution and natural selection to advocate “racial engineering” and the flip side, racial extermination. From Haeckel’s book Die Lebenswunder:
“What profit does humanity derive from the thousands of cripples that are born each year, from the deaf and the dumb, from cretins, from those with incurable hereditary defects, etc., who are kept alive artificially and then raised to adulthood? ….. what a loss in terms of private resources and costs to the state for the healthy!”
Also, ideas of Nordic and Aryan superiority were quite widespread at this time. As in H.F.K. Gunther’s book Ethnology of the German Nation:
“The man of Nordic race is not only the most gifted but also the most beautiful. There stands the slim figure of the man, raised up to a triumphant blend of bone and muscle on a magnificent scale-the broad, powerful shoulders, the wide chest and narrow hips. The woman has slim, rounded shoulders and broad but slender curved hips….a sovreign race”
Even such authors as the well known and renowned H.G. Wells supported such ideas about race. His 1901 work Anticipations contained ideas very similar to those presented in Hitler’s Mein Kampf.
This is not to say that the majority of people in this time period agreed with this racist rhetoric, only that there was a climate of opinion that was conducive to these ideas.