Darwin and Eugenics

https://barryhisblog.blogspot.com/p/darwin-on-eugenics.html

Whether or not Darwin supported or advocated eugenics is irrelevant to the truth of evolution. It is an infantile attitude that says, "I don't like this so it can't be true". Most of us grow out of that way of thinking by about the age of three.

But in fact, Darwin was against the idea, as the following passage shows, and his reasoning, as usual, is worth examining. 

"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. We must therefore bear the undoubtedly bad effects of the weak surviving and propagating their kind; but there appears to be at least one check in steady action, namely that the weaker and inferior members of society do not marry so freely as the sound; and this check might be indefinitely increased by the weak in body or mind refraining from marriage, though this is more to be hoped for than expected." - Charles Darwin, The Descent of Man and Selection in Relation to sex. http://darwin-online.org.uk/content/frameset?pageseq=1&itemID=F944&viewtype=text

People have been selectively breeding their crops and livestock for millennia. It doesn't take "Darwinism" for people to understand that you can shape organisms to your benefit by controlling reproduction. 

But people have also been caring for the sick, disabled and malformed for millennia. Our "instinct of sympathy" predates any modern religions, and the care is not withheld because it is costly in resources, or because the cared for cannot contribute. https://www.nytimes.com/2012/12/18/science/ancient-bones-that-tell-a-story-of-compassion.html

As Darwin notes, we cannot "check our sympathy" without losing our humanity. When we do check our sympathy, the result is murder and genocide. We lose our humanity when we dehumanise others.
 
See also, https://www.newscientist.com/article/dn13689-evolution-myths-evolutionary-theory-leads-to-racism-and-genocide/