Being made to feel Darwin's anguish

The pain that Darwin felt when his beloved 10-year-old daughter died is well known. Annie was his favourite, and her death stripped him of the last vestiges of his belief in Christianity.

Watching this film about Darwin's life, I felt his pain – in having to sit through nearly two hours of Annie's ghost appearing to him and admonishing him. "Don't you dare give up on your book, daddy," it says, wagging its finger when Darwin is agonising about the reception his work will get. I desperately didn't want to give up on the film, but well before the end it had lost me.

Paul Bettany's Darwin, whom we first see in Tierra del Fuego on board the Beagle, starts the film charismatic and amiable. No stranger to this sort of role, Bettany previously played the fictional 18th-century ship's surgeon and proto-Darwinian Stephen Maturin in Master and Commander. Darwin's wife, Emma, is played by Jennifer Connelly (Bettany's real-life wife), who is likewise on familiar ground: she was once cast as the spouse of another scientific genius, mathematician John Nash, in A Beautiful Mind.

It's wonderful to see Darwin played as a young man and a father, passionate, mischievous and inspiring, rather than portrayed as the name behind the idea, or the bearded old man of those familiar black-and-white photos. No problem either with the dramatisation of his complex relationship with God-fearing Emma. And the touching scene when Darwin meets Jenny the orang-utan – the first time he'd come face to face with a great ape – is beautifully executed, brilliantly capturing the humanity of our fellow apes.

The problem with the film is the conceit of having Annie materialise and interact with Darwin in order to illustrate the impact her death had on him. As a device, it is unsubtle and irritating, and makes for a cartoon account of the writing of On the Origin of Species, one that presupposes that an audience will only appreciate Darwin's anguish if it is spelled out in gigantic, sentimental letters waved by a pretty ghost.

I put this view more gently to Randal Keynes, Darwin's great-great-grandson, who wrote the book Annie's Box – an account of Darwin's family life and of his relationship with Annie in particular – and who gets a writing credit on this movie. "The film is based on the knowledge that Darwin lived with the memory of his daughter all his life. He was a man of passion, and people have missed that," said Keynes. "Putting the ghost in can be regarded as the film producer's license to tell the story."

We should be thankful that Darwin's life story has made it to the big screen, yet even before Annie has died, the film shows its scorn for the ability of the audience to appreciate the subject matter. In case anyone was in doubt about the ire Darwin's work would arouse, the local vicar is seen telling him, "You're pitting science against God!" This is a child's guide as to why there might just be a conflict of interest in some people's minds between natural selection and religion.

A dramatised account of the development of "the single best idea anyone has ever had", as Daniel Dennett called the theory of evolution, needs exceptional treatment. If only this film had got it.