In support of his claim that the theory of evolution inspired Nazism, Ben Stein attributes the following statement to Charles Darwin's book The Descent of Man:^[28]

With savages, the weak in body or mind are soon eliminated. We civilized men, on the other hand, do our utmost to check the process of elimination. We build asylums for the imbecile, the maimed and the sick. Thus the weak members of civilized societies propagate their kind. No one who has attended to the breeding of domestic animals will doubt that this must be highly injurious to the race of man. Hardly anyone is so ignorant as to allow his worst animals to breed.

The original source shows that Stein has significantly changed the text and meaning of the paragraph, by leaving out whole and partial sentences without indicating that he had done so. The original paragraph (page 168) (words that Stein omitted shown in bold) and the subsequent sentences in the book state:^[28][72]

With savages, the weak in body or mind are soon eliminated; and those that survive commonly exhibit a vigorous state of health. We civilized men, on the other hand, do our utmost to check the process of elimination. We build asylums for the imbecile, the maimed and the sick; we institute poor-laws; and our medical men exert their utmost skill to save the life of every one to the last moment. There is reason to believe that vaccination has preserved thousands, who from a weak constitution would formerly have succumbed to small-pox. Thus the weak members of civilized societies propagate their kind. No one who has attended to the breeding of domestic animals will doubt that this must be highly injurious to the race of man. It is surprising how soon a want of care, or care wrongly directed, leads to the degeneration of a domestic race; but excepting in the case of man himself, hardly anyone is so ignorant as to allow his worst animals to breed.

The aid which we feel impelled to give to the helpless is mainly an incidental result of the instinct of sympathy, which was originally acquired as part of the social instincts, but subsequently rendered, in the manner previously indicated, more tender and more widely diffused. Nor could we check our sympathy, even at the urging of hard reason, without deterioration in the noblest part of our nature. The surgeon may harden himself whilst performing an operation, for he knows that he is acting for the good of his patient; but if we were intentionally to neglect the weak and helpless, it could only be for a contingent benefit, with an overwhelming present evil.^[72][73]

According to John Moore writing in the National Post:

Stein quotes from a passage in Darwin's writing that appears to endorse the notion that for a species to thrive the infirm must be culled. He omits the part where Darwin insists this would be "evil" and that man's care for the weak is "the noblest part of our nature." When I asked Stein about this on my radio show he deadpanned, "If any Darwin fans are listening and we have misquoted him, we are sorry; we don't mean to diss Darwin."^[74]

The Expelled Exposed website also points out that the same misleading selective quotation from this passage was used by anti-evolutionist William Jennings Bryan in the 1925 Scopes Trial, but the full passage makes it clear that Darwin was not advocating eugenics. The eugenics movement relied on simplistic and faulty assumptions about heredity, and by the 1920s evolutionary biologists were criticizing eugenics. Clarence Darrow, who defended the teaching of human evolution in the Scopes trial, wrote a scathing repudiation of eugenics.^[75]