Charles Davenport following Galton's theories was the main progenitor of eugenics right here in the USA. The Germans appropriated their work till it culminated into the campaign of extermination of undesirable masses. I would recommend the interested to read Edwin Black's "War Against The Weak". Without a spiritual basis to life's sacredness all roads will eventually lead to a Mengele judgement.
US rally shows support for ex-Marine held by Iran on spying charges (AP)
from the article: In his diary, Mengele predicted 90% of humans would die of stupidity