"Creation: The True Story of Charles Darwin."

The unease in Darwin's marriage isn't the only thing contributing to Darwin's angst. He must suffer through the cloying brand of Christianity championed by his erstwhile pastor, as well as the urgings of scientific colleagues who are only too happy to get rid of the Man Upstairs. (One scene shows Darwin wincing when fellow biologist Thomas Huxley, who came to be known as "Darwin's bulldog," gleefully tells him, "You've killed God, sir!")

The source of Darwin's deepest sorrow is the death of his 10-year-old daughter, Annie, in 1851. "Creation" depicts Darwin as literally haunted by the girl, who suffered from scarlet fever and tuberculosis (or consumption, as it was known back then) and was subjected to dousing, scrubbing, sweating and other medical treatments that seem extreme today.

Did Annie's travails sharpen Darwin's own views on the struggle for existence by the time "The Origin of Species" was published in 1859? Randal Keynes, Darwin's great-great-grandson, thinks so - and he argues the case in the biography on which the movie is based.

Keynes' book was originally released in Britain in 2001 under the title "Annie's Box," and was later published in the United States as "Darwin, His Daughter and Human Evolution." Now the book is being republished as a paperback movie tie-in, titled "Creation: The True Story of Charles Darwin."

Here's an edited transcript of our chat:

Cosmic Log: In the book, you draw out the idea that the personal tragedy Darwin went through helped sharpen what he wrote in “The Origin of Species.” Can you talk about how that was reflected in the movie?

Randal Keynes: Neither the book nor the movie suggests that Darwin drew directly from his experience of Annie’s childhood and loss for any of the ideas in the book. What I would say is that Annie’s death must have been one of the elements, because it was his most powerful experience of death and bereavement. …   That must have been important in his thinking about pain, and loss, and struggle.

It was therefore an element in his thinking about the “struggle for existence.” I mention how it was, in certain passages of his writings about the struggle for existence, that he used different language after his experience from what he had written before.

But that’s not the most important point, I think. The experiences of life with Annie and her death were important to Darwin in his idea about the natural origin of the human moral sense. He came to hold the view that the human moral sense arises not from principles laid down by God or anyone else, but in a complicated way from how we care about other people who are important to us – which is a natural instinct. How we develop our thinking about people who are important to us, and how we should treat them when we have language to communicate, and set ourselves rules, and so on.

If you read what Darwin said about the natural origin of the human moral sense in “The Descent of Man,” his second great book, you find again echoes of things he learned from his life with Annie.

The very important thing about “The Origin of Species” is that he avoids talking about human nature in it. He knows just how explosive any suggestion that humans are part of the pattern of evolution would be. He puts nothing explicit into “The Origin of Species,” he just leaves it as an unspoken implication. When he finds that other people haven’t gone on to tease out the implications for humans in the theory of evolution, he decides, “OK, I’m going to write the second book, ‘The Descent of Man.’” He explains there that humans are a part of the story.

Q: Right, you mention in the book that he was hoping that Alfred Russel Wallace, an evolutionary theorist who was a contemporary and something of a rival, would write something about that.

A: But he didn’t.

Q: What really struck me about the movie was how grim Darwin’s life experiences sometimes became. I’m not sure that comes through so much in the book – just those dark depths of grimness.

A: The movie is doing quite a lot in combining strands and weaving them into the picture that the movie presents. It takes a number of elements in Darwin’s life, in the way that movies always do, and puts together things that were actually some way from each other.

Q: It would be good for people to know that. After seeing the movie, I looked back and found that Darwin was indeed troubled by illness for a large part of his life. But I see what you’re saying: that some of the parts of the story may have come from a later phase in Darwin’s life, after “The Origin of Species” was written.

A: Or at other times during the writing. As a Darwinist, I would say that for every important element in the film, there is a source in Darwin’s life and writing and in our knowledge about him. The source material doesn’t fit together in precisely the way that it does in the film. I think that the film is not a work of historical biography.

The film works by giving an impression of basic truths, a history of a person’s life and situation. The impression very often can go beyond what there is chapter and verse for in the historical record – because it depends on the imagination that we use in interpreting what we learn about the person. You make guesses about what that person is feeling and doing. It’s part of human nature, part of the way we understand people.

Q: So you feel that the film captures the essence of Darwin’s life and work?

A: The film does that. I think it’s right to present Darwin as a man of passion as they do. A man under pressure, and sometimes buckling under the pressure. It’s really valuable to show him that way after 100 years of portrayal of him as this bearded prophet with no humanity at all. Some people make it sound as if he just produced this theory out of thin air by the objective marshaling of evidence. That just doesn’t get to the heart of the excitement of the theory, or the difficulties that Darwin had in working it out. It’s right to show Darwin in this new way, because that is closer to the true nature of the man than this stereotype.