'For 21 years, he kept his theory secret' read the posters appearing on bus-stop shelter walls and phone booths across New York. The posters are for Darwin, the largest exhibition to date chronicling the life and work of the 19th-century naturalist at the American Museum of Natural History in Manhattan.

It's a tantalising teaser line that suggests scandal - and a timely marketing strategy that is sure to draw crowds. Across the US, heated debates and numerous lawsuits have been brewing over whether Darwin's theory of evolution via natural selection should be replaced in publicly funded schools with a more Bible-friendly alternative known as intelligent design - a concept that argues that evolution was masterminded by a supreme being.

Although the Darwin exhibition, which opened in November and runs until 29 May, was not conceived as a direct response to the current political fracas, the show - and several other exhibitions in the US that address evolution from a scientific standpoint - raises important questions about the changing role that museums are now playing in educating audiences on the theory of evolution as it is challenged by schools and in the courts.

A poll conducted by the Pew Research Center for the People and the Press and Pew Forum on Religion & Public Life at the end of last year found that 64 per cent of Americans surveyed are open to the teaching of both creationism and evolution in public schools, while 38 per cent favoured dropping evolution altogether in favour of creationism.

In the same poll, 42 per cent of those surveyed believe that life on earth has remained the same since the beginning of time. And while 48 per cent believe that some form of evolution occurs, only 26 per cent agree with Darwin's theory of natural selection, and 18 per cent uphold that evolution was guided by a higher being.

According to the National Center for Science Education in California, which defends the teaching of evolution in US public schools, 17 legislative actions to offer intelligent design as an alternative to Darwinian theory in public schools were filed between 17 January and 21 August 2005. This is up from only eight similar bills in the whole of 2004 and reflects the rising support for anti-evolutionary education in the US.

A high-profile, headline-grabbing case in the small town of Dover, Pennsylvania, put a spotlight on the intensity of the current debate between proponents of intelligent design and those who advocate the teaching of Darwinian theory.

Christian conservatives in Dover believed they could persuade the local school board to offer intelligent design instead of the more established textbook lessons on natural selection.

But in December a federal district judge ruled that such action violated the secular nature of the Constitution of the US and ordered the Dover school district to forbid a theological approach in the classroom.

Where does this polarising debate leave museums, which are seen as bastions of objective education? After all, a widely cited poll, conducted by RKM Research and the Western Research Group in 2000, states that 43 per cent of Americans consider museums a trustworthy source of information, compared with only 18 per cent who saw books as credible sources, and 9 per cent who saw newspapers as reliable.

Some might argue that science and natural history museums have a responsibility to teach Darwinian theory, especially now schools might opt out. But museums have to worry about retaining funding from corporate sponsors, some of which could be headed by Christian conservatives.

They also want to avoid legislative action parallel to that being filed against school districts. And how do they avoid upsetting visitors whose beliefs reflect those of the supporters of intelligent design? In light of all of this, are museums shying away from an authoritative stance on evolution?

'It's amazing how much emotion the concept of evolution raises now. If a show's title features the word, it will generate controversy,' says Lance Grande, a curator and vice president for research and collections at Chicago's Field Museum. This is one of the venues the Darwin exhibition will travel to and the site of another exhibition related to evolution, Evolving Planet, which opens next month.

The American Museum of Natural History's $3m Darwin exhibition, is carefully organised to make its specific objectives clear: it is a blockbuster show devoted to an influential figure in the scientific discipline of biology.

It was conceived as merely one show in an ongoing series devoted to legendary personalities in the realm of science; previous exhibitions featured the lives and work Albert Einstein, Leonardo da Vinci and Ernest Shackleton.

The Darwin show is to travel to four other museums: Boston's Museum of Science, Chicago's Field Museum, Toronto's Royal Ontario Museum, and finally to London's Natural History Museum.

It will be on view in Darwin's native England during the bicentennial of his birth in 2009 - a year of double significance as it also marks the 150th anniversary of the publication of his seminal work On the Origin of Species.

The show's signage makes it clear that even 150 years later, Darwin's theory of evolution via natural selection still sparks controversy, as it did when he was alive. Guides and wall text point out that he was reluctant to publish his theory, fully aware that it would be interpreted as contradictory to Christian doctrine.

The curators build up the narrative through the exhibition layout. From the first introductory section, the audience learns that before Darwin began to develop his ideas on evolution, human beings were understood as removed from the world of animals.

Further into the exhibition, a showcase features the young Darwin's personal Bible, which he took with him on his voyage on the HMS Beagle. Later displays cover the denunciation of his theory of evolution at a meeting of the British Association for the Advancement of Science, held at Oxford University Museum in 1860.

And the final section of the show features a timeline of controversy, including the 1925 Scopes 'monkey trial', in which the American state of Tennessee established the teaching of evolution in public schools as a misdemeanour crime, and right up to the recent drama in Dover, Pennsylvania.

But the exhibition is primarily about Darwin the person. The show features more than 400 objects and living specimens, and serves as an intimate portrait of Darwin, the remarkable thinker and towering figure in scientific history.

Pages and pages of immaculately preserved personal letters are neatly displayed under glass, along with the notebooks that Darwin brought with him to the Galápagos and in which he first jotted down the observations that led him to conceive of the theory of natural selection.

Some insect specimens that Darwin collected are also on view. Photographs of his family, a life-sized replica of his study/laboratory at his country house, and a heartbreaking recollection of the death of his daughter as a child, help to build a three-dimensional portrait of the influential naturalist.

Yet as if to pre-empt arguments from proponents of intelligent design or creationism, the curators have included signage that defines what the word 'theory' means within a scientific, rather than popular, context: a concept that is based on extensive evidence and is heavily corroborated, such as gravitational theory. The exhibition also makes links between Darwin's research and modern genetics, thus providing contemporary relevance.

In contrast to the motives behind the organisation of the Darwin exhibition, Explore Evolution was developed by curators and educators at the University of Nebraska, Lincoln, as a direct response to what they felt was a move away from the teaching of Darwin's theory over the past three decades.

The project was spearheaded by Judy Diamond, a professor and curator at the University of Nebraska State Museum. It was funded by a $2.8m grant from the National Science Foundation and is intended to educate the public on the subject of evolution rather than making any sort of political statement on the issue.

According to news agency Agence France-Presse, since the exhibition has been on view in Lincoln, about 10 per cent of visitor-survey cards indicated that audience members were against the Darwinian theory. Versions of the show are on view simultaneously at public American universities in Kansas, Michigan, Minnesota, Oklahoma and Texas.

Some institutions are preparing for a pro-creationism audience backlash against the presentation of Darwinian theory within museum walls. The Museum of the Earth in Ithaca, New York, last year developed a staff-training programme to help guides cope with queries and criticism from visitors who question why evolution, rather than creationism or intelligent design, is highlighted in an exhibition.

The programme consists of a 13-page guidebook and a workshop. Museum administrators around the US have shown interest in this organised, pre-emptive approach: more than 70 inquiries have been made about the programme, and more than 100 museum workers - and members of the general public - signed up for the first two workshops at the Museum of the Earth last year.

The sessions include advice such as advocating that a science museum is focused on science above political or theological opinions, and playing the role of an active listener rather than a reactionary defender.

In preparation for the upcoming Evolving Planet exhibition at the Field Museum, exhibition guides were required to attend a training programme that ran over nine weeks, the longest one the institution has held to date. It included how-to sessions on answering questions about intelligent design as well as evolution.

As if to take advantage of the public idea of the museum as credible educational institutions, newly formed (and well-funded) institutions devoted to creationist themes are also emerging around the US.

In Fort Lauderdale, Florida, the Creation Discovery Center, the product of an 18-year-old ministry known as the Creation Studies Institute, is starting to be seen as a prototype for other museums that promote what is called 'young earth creationism'.

It's a movement that upholds the Bible's account of the world's creation in six days by God some 6,000-10,000 years ago, based on calculations of the collective lives of Biblical characters, as opposed to the four billion-plus years that scientists generally estimate.

At the Creation Discovery Center, visitors can see statues and mannequins depicting Noah and the Biblical flood, juxtaposed with exhibits on the Tyrannosaurus Rex and the Ice Age.

Different epochs in the earth's history are re-contextualised according to the Biblical flood (as in pre- and post-flood), ignoring geological research. Similar faith-based institutions exist in Kentucky, Texas and California.

Charlie Carlson, a biologist and the director of life sciences at the Exploratorium, a science museum in San Francisco, says the issue of how to cope with the intelligent design debate is a hot topic for the museum community: 'It's frequently discussed on science-news online discussion groups.'

But even though biology-related displays do mention evolution, he says, 'there haven't been many visitor remarks questioning Darwin's theory in the years I've been on staff… I think visitors know that a science museum presents science, not religion.'

The final word goes to the Darwin exhibition. It states: 'Creationism, including intelligent design, does not offer a scientific alternative to the theory of evolution.

By invoking the act of a creator or an intelligent designer as the explanation for life's diversity, creationism invokes a cause that lies outside our powers of observation and thus outside the realm of scientific inquiry.'

Reena Jana is a freelance journalist based in New York