To some creationists, Darwin was not only wrong but poisonous - his evolutionary theory, they say, directly influenced Hitler's genocidal ideology.
Historian Richard Weikart appeared in the anti-evolution film Expelled, promoting this alleged Darwin-Hitler link. Weikart has written extensively on this, arguing that Darwinian evolution destroyed Judeo-Christian morality, especially the notion of reverence for life.
Weikart does not try to push the idea that this invalidates evolution as a scientific idea. But he is openly creationist - a fellow at the Intelligent Design-promoting Discovery Institute in Seattle.
His message is that evolution kills morality. "If everything is a product of chance - purposeless - which is widespread in biology textbooks . . . then I don't think you have any grounds to criticize Hitler."
Those are fighting words, and a number of thinkers have challenged them. Most recently University of Chicago historian Robert Richards took Weikart to task in a paper titled "Was Hitler a Darwinian?", to which he answers a definitive no.
Weikart said he began exploring the topic when he wrote his dissertation on the influence of Darwin on German socialism in the 19th century. There, he said, Darwinism was used to justify eugenics - the attempt to influence selection in the human race, usually by killing or sterilizing anyone considered "unfit."
As Weikart learned more, he said, "the connection to Nazism leapt out at me." Darwin's second evolution book, The Descent of Man, is rife with racist statements about "higher" and "lower" races, said Weikart, and Darwin viewed the extermination of native people in Tasmania and Australia as part of natural selection.
Darwin, Weikart admits, didn't advocate such killings, and he abhorred slavery. Darwin also disavowed the more extreme eugenicist views, instead saying that helping those in need exercised the better part of our nature.
But Darwinian thinkers of Hilter's time were trying to use evolution to justify racism, said Weikart, and this influenced Hitler. "Hitler spoke and wrote incessantly about evolution, natural selection and the struggle for existence, especially the struggle between races," he wrote in one of his books.
Richards calls this all a desperate tactic to undermine evolution. Creationism and Intelligent Design don't hold up scientifically, he said, so people like Weikart are trying to show that evolution is somehow morally dangerous.
"There's not the slightest shred of evidence that Hitler read Darwin," he said. Some of the biggest influences on Hitler's anti-Semitism were opposed to evolution, such as British writer Houston Stewart Chamberlain, whose racial theory became incorporated into Nazi doctrine. Hitler uses language with "a Darwinian flavor," said Richards, but if you look at the ideas behind it they have nothing to do with Darwin.
Hitler often used the word Entwicklung, Richards said, which can mean evolution but is a much more general term meaning development, and Hitler most often employed it to refer to economic development. "It's quite unfair to translate this as evolution," he said, as Weikart does.
While some of Darwin's writings contain racist notions of a hierarchy of races, Richards said, this was inherited from much earlier work and was part of the then-current mode of thinking.
Daniel Gasman, a historian at City University of New York's John Jay College, has also written that Darwin wasn't a major influence on Hitler but he does see a connection with German biologist Ernst Haeckel, who was one of Darwin's fiercest disciples.
Gasman wrote a book called Scientific Origins of National Socialism connecting Haeckel's influence to Hitler and Nazi ideology. Stephen Jay Gould read it and popularized the idea further in his own writings.
Haeckel was Germany's most famous scientist, said Gasman. He advocated evolution but his conception of it was different from Darwin's - he saw progress and advancement where Darwin noted only change. "Haeckel's Darwinism is a vast transformation of what Darwin wrote and stood for," Gasman said.
Haeckel also created his own religion, called monism, which tried to replace the Judeo-Christian idea of separate spiritual and physical worlds with a more integrated view.
Gasman said examples abound showing that Haeckel was a leader in anti-Semitic thought. Richards said his research shows Haeckel was militantly atheistic but not anti-Semitic - he disliked both Judaism and Christianity in equal measures.
They both agree that any whiff of Darwinism in Hitler's speech or writing was merely window-dressing. The Nazis did try to look scientifically sophisticated, Gasman said. "They took anti-Semitism and gave it a scientific character that propelled them forward," he said. "That's why it was so murderous."
The historians also agree that evolution's validity as a scientific concept is unaffected by this controversy. "Even if Hitler said all his inspiration for persecuting the Jews derived from Darwin, it would say nothing about the validity of evolution," Richards said.
Weikart's view that evolution's proponents lack the moral grounds to criticize Hitler raises this question: Why should we hold evolution responsible for providing a complete moral framework? We don't ask that of Galileo or Newton or Einstein. Weikert replies that evolution is different because various thinkers have applied it to morality.
But there are many ways to spin the moral influence of Darwin. Perhaps instead of creating chaos, it might be helping us construct a more informed and less rigid morality. Darwin himself wrote that violence, selfishness, charity, and goodwill are all part of human nature. He hoped we would choose to act on the better parts.
And the element of chance to which we owe our existence could provide inspiration rather than moral decay. If our lives really did hinge on countless accidents, couldn't that notion make life ever more precious?
Contact staff writer Faye Flam at 215-854-4977 or email@example.com. Read her evolution blog at www.philly.com/evolution, or follow her on twitter @darwins_hellcat.