English ethologist Richard Dawkins, famed for his outspoken opinions about religion, is catching backlash on Twitter after saying eugenics would “work for humans.”

“It’s one thing to deplore eugenics on ideological, political, moral grounds. It’s quite another to conclude that it wouldn’t work in practice. Of course it would. It works for cows, horses, pigs, dogs & roses. Why on earth wouldn’t it work for humans? Facts ignore ideology,” Dawkins wrote.

Eugenics is the practice of selective breeding supported by the Nazis. 

Greg Epstein, Humanist Chaplain at Harvard University, responded to Dawkins tweeting, “So unacceptable for Richard Dawkins to tweet about eugenics without clearly condemning it. Dawkins is *supposedly* one of our exemplars of humanism & science outreach. Yet today he’s given every manner of passive and active bigot an opening to “consider” persecution on steroids.”

Charles M. Blow, a columnist for the New York Times also reacted writing, “This eugenics crap is so dangerous. In the US it lead to forced sterilizations of women in the South — sometimes against their wills, often without their knowledge — that became so common that they came to be referred to as “Mississippi appendectomies.”

Dawkins recently appeared on an episode of The Joe Rogan Experience, which you can watch here.