One doesn't think of Charles Darwin's On the Origin of Species, nor of Darwin himself, as the sort of compelling subject matter that could fuel a sweeping love story.

This was certainly true of the majority of the cast and crew of Creation, the English film that kicked off TIFF last night, it was admitted at a press conference about the film earlier this morning.

That was, until a book called Annie's Box, written by the great great grandson of Darwin, Randal Keynes, was brought to the attention of screenwriter John Collee, then to director Jon Amiel and eventually to actors Paul Bettany and Jennifer Connelly. One by one their perceptions of one of the most influential men of all time changed.

For Keynes the journey began when he discovered a box in the family stead in Kent. This box turned out to contain mementos of Darwin's daughter Annie, who passed away at a young age. The discovery led to a quest to paint a portrait of Darwin as more than an intellectual, a scientist, but as a loving and then grieving father, and a man deeply in love with his wife, Emma.

"This box was just charged with emotion," said Keynes.

What attracted Collee to Keynes' book was that it made a man who has become his idea human again.

"The extraordinary thing about Randal's book is that it takes the character of someone whose writing is rather dry, an old-fashioned scientist, and he really added a wonderful level of modern humanity and passion to the man and that's what threw me into it," Collee explained.

"There was no separation between Darwin's creative life and his family life. An intensely creative life can also be intensely connected to the people you love and who are important to you - wife, children. As a result of family conflicts Darwin produced his most enduring work."

When Amiel was working with Collee to develop the script he was acutely aware that he didn't want the film to become a biopic of Darwin's life, a chronological narrative of his milestones and achievements. So he and Collee wrote a story that isn't linear, but one that is organized emotionally, jumping between the moments in Darwin's life that held particular emotional significance to him.

"I'm not a fan of the biopic genre," Amiel said.

"I don't like historical drama-documentaries and so I started out completely sceptical about the whole enterprise. But [in the book] you start to hear their own words, you start to feel them in a real, palpable way. Their emotional life, their voices, much of their language is actually in the script. We weren't going to tell a linear story, because Darwin's life has such a bizarre shape to it. It's not an easy life to shape. We decided very quickly to make our story non-linear, to organize our story emotionally rather than chronologically and to paint a passionate portrait of a man that we increasingly came to realize was an intensely passionate and emotional man."

What has emerged seems to be a work of heart. All involved in the film spoke sentimentally about it. And in fact, the film is quite sentimental, without seeming overdone. Much-publicized has been the fact that real-life couple Connelly and Bettany play Charles and Emma Darwin.

Connelly said that working with her husband is nothing less than a "privilege," and that Creation was the perfect project for them to star in together. She highlighted the fact that the Darwins knew one another their whole life and were in fact first cousins. She said that perhaps being as familiar with one another as she and Bettany were heading into filming helped them to recreate that lifelong love on-screen.

"I thought it was beautifully written," she said of the script.

"It put everything I knew about Charles Darwin into context and I thought it was the most remarkable story. I was surprised by the lack of information I had about his personal history and family life. I found it compelling. I found their love story inspiring and truly magnificent. I thought that Emma Darwin was a formidable and exemplary woman, so I thought it was a very exciting prospect."

As far as pitfalls go, Connelly insisted that the Darwins' characters and relationship were so different from their own that there was never a danger of recreating their romance on-screen instead of the Darwins'.

"There's so many things that seem to help to keep things separate," Connelly said.

"Such a different world, such a different language. She felt like the most different person that I've ever played. And the context and the subject matter...everything felt very much their story. I didn't really feel that we were discussing our story. It felt very clear to us that this was their story."

Bettany added that, rather than being a pitfall, being able to see the familiar in the picture of Darwin created by Keynes' book and Collee's script allowed him to relate to an otherwise daunting historical figure.

"I personally have to cling to those things, those things that you can identify with, that can be about you, especially when you're playing someone who had arguably the greatest idea a human being has ever had," he admitted.

"I'm naturally blonde and an actor; I can only fake that. I can't be that bright. But I do know what it's like to be a father and I do know what loss feels like and I do know what being in a committed relationship with children is like, so those things are actually concrete to me and the safety net to having to look really smart."

And it is in this humaness, these basic life truths being portrayed so successfully on film, said Keynes, that makes the movie so poignant.

"One thing I think is remarkable about the film is two episodes: Darwin with Annie as an infant and then with Jenna the orang. They work extraordinarily well, I think, because they found basic truth about the father and the child, the human and the orang. That basic truth carries the episodes and carries the film."