Think of two characters wrestling with the age-old clash between humanity and science - say, Dr McCoy and Mr Spock or agents Mulder and Scully. The new forensic drama Bones walks a similar line with Booth, an FBI agent who depends on instinct, and Brennan, a forensic anthropologist in the clinical CSI mould.

"This is struggle between the rationalist versus the humanist," executive producer Hart Hanson says. "Star Trek did it, Moonlighting did it, certainly The X Files did it. It’s a time-honoured tradition in storytelling."

Bones is set in the fictional Jeffersonian Institute (a thinly veiled take on the US’s venerable Smithsonian) and focuses on the crime-solving work of top-of-her-field forensic anthropologist Dr Temperance Brennan (Emily Deschanel) and FBI agent Seeley Booth (David Boreanaz).

The series is based on the work of author and forensic anthropologist Kathy Reichs, who was profiled in a TV documentary watched by Hanson (Joan of Arcadia, Judging Amy) and his co-executive producer, Barry Josephson (The Tick). In a curious, complex homage, the fictional Brennan sidelines as an author of novels about a fictional (in her world) anthropologist named Kathy Reichs.

Hanson concedes he was reluctant to produce a procedural drama. "It’s heavily travelled territory. I really wondered what was I going to do differently. They’re great shows - CSI, Cold Case, Without a Trace - they’re just not my kind of show.

"There is a certain kind of writer that likes a procedural, that likes doing the puzzle, and to me the puzzle is secondary to what the people go through - what is it like for someone to work with hideous remains and bones and what kind of person goes into that line of business?"

Hanson and Josephson eventually settled on something with a different tone - a procedural structure with a lot of character emphasis. "We have a lot of digression, a lot of tangents," Hanson says. "These two different people, the FBI agent and the scientist, have very different approaches. And we wanted to put in a lighter touch because procedurals do not normally have much humour in them."

Of all the elements, the last was the most challenging. "It’s risky," Hanson admits. "The tonal shifts in our show are large; it’s our strength and it’s our weakness. At every stage I have said this could fail because when you have characters joking, even if they don’t know they’re being funny, if there’s a light sense of humour over a dead body, you run the risk of offending people. I don’t mean prudishly. I just mean in some human sense.

"But I, like most TV writers, have spent time with cops, coroners, doctors and emergency room people when they’re working, and they’re very funny. It is their way of coping with their world."

Hanson and Josephson pitched the series to three networks but Fox eventually bit. Sitting in his office on the 20th Century Fox lot in Century City, Los Angeles, Hanson reveals one of the black arts of the TV trade - that each pitch was different.

"Every network you go to you actually tailor the pitch for the character of that network," he says. "At [older-audience skewing] CBS, for example, the lead character would have been older and the tone would have been slightly more orthodox. For Fox, we needed someone younger and a tone that was a little edgier."

Boreanaz was cast first. "We needed the qualities of an old-time Gary Cooper or Spencer Tracy, a guy to be the humanist so he wouldn’t be weepy and New Age," Hanson says. Brennan needed to be "sexy, smart and funny and we constantly had two of the three come in. Emily had all three plus a gravitas that puts her beyond her years."

Curiously, Bones reflects a broader trend in procedural dramas. Without a Trace has exploited character material, particularly the agonising divorce of Jack Malone (Anthony LaPaglia), with great dramatic effect. Even CSI, the most clinical of the procedurals, is now dabbling in character stories.

"If the audience is devoted, they will start recognising the rhythms of the show and get bored," Hanson says. "Character stories are a way of disrupting that rhythm and I think every writer and every actor wants to do character stories. They want to play more than ’this looks like a hair’."

Bones begins on Seven on Thursday at 9.30pm.