Did you hear the one about the amusing Booker Prize shortlist?

A Man Booker shortlist comprising stories that were inspired by the Austrian abductor-rapist, Josef Fritzl, 19th century slavery, an inquiry into Jewishness and a master-and-slave journey into America's prisons might sound like serious business.

But the verdict of this year's judges on the shortlist of six novels was that it was the most humorous in the 42-year history of the prize, despite the dark, disturbing subject matter.

Sir Andrew Motion, the former poet laureate and the chairman of the judges, said they had not "set out to create a gallery of funny books". He added that while the choices were not necessarily "laugh out loud" funny - perhaps with the exception of The Independent columnist Howard Jacobson's The Finkler Question - they were fine examples of tragic-comedy.

"Jacobson's and Peter Carey's are funny books. Andrea Levy's The Long Song is a more surprisingly comical book and there is a lot of comedy about Tom McCarthy's novel as well," said Motion.

Ion Trewin, the literary director for the Man Booker prizes, felt the shortlist "was the funniest in the history of the prize," notwithstanding Emma Donoghue's Room , which takes its inspiration from the real-life case of Josef Fritzl, who kept his daughter captive in the basement of his family home. It is now the bookmaker Ladbrokes' favourite to win the £50,000 prize next month.

For most readers, however, the biggest surprise in the list will be the notable absence of David Mitchell's fifth book, The Thousand Autumns of Jacob de Zoet , which was among the biggest sellers on the longlist, second only to Christos Tsiolkas's The Slap , which sold the most copies out of the 13 books to be longlisted in July and which faced charges of misogyny.

Motion said that while Mitchell, a twice Booker-nominated author, "is a writer I greatly admire... we did not like it [his book] enough."

Simon Burke, from Waterstones, expressed surprise over the absence. "The news that Mitchell has not made the shortlist will cause great wailing and gnashing of teeth across the bookworld," he said.

Jonathan Ruppin, from Foyles, added: "The omission of both Mitchell and Tsiolkas from the shortlist is a real shock... I imagine it took some wrangling amongst the judges to reduce one of the best longlists in years to six."

Motion spoke in glowing terms about those who did make the cut, likening the literary prowess of the Carey, to that of Charles Dickens.

Shortlist: Carey could be first to win prize three times

Peter Carey

Parrot and Olivier in America

Olivier is a child of survivors of the French Revolution; Parrot is the son of an English printer who wanted to be an artist but ended up as a servant. They join for a picaresque journey to America. Carey won the Booker for Oscar and Lucinda (1988), and for True History of the Kelly Gang (2001).

Excerpt "I have no doubt that something cruel and catastrophic had happened before I was even born, yet the comte and comtesse, my parents, would not tell me what it was."

Howard Jacobson

The Finkler Question

A study of Jewish identity featuring two middle-aged men Julian Treslove, a former radio producer, and Sam Finkler, a Jewish writer and television personality. Jacobson has been longlisted twice for the Booker for Kalooki Nights (2006) and Who's Sorry Now? (2002). He writes a weekly column for The Independent.

Excerpt "He should have seen it coming. His life had been one mishap after another. So he should have been prepared for this one..."

Damon Galgut

In a Strange Room

Features a young man's journey through Greece, India and Africa, where he meets a handsome stranger, a group of backpackers and a woman on the edge. Galgut's books include The Good Doctor, which was shortlisted for the Man Booker Prize in 2003.

Excerpt "Even before her departure when he goes to meet her flight from Cape Town, he knows he's in trouble. He last saw her a month ago and she was in a bad way then."

Andrea Levy

The Long Song

The story of July, a slave girl born on a sugar plantation in the 19th century and selected by a white mistress to live with her as a lady's maid. Of her four previous novels, Small Island won the 2004 Orange Prize and was made into a BBC drama in 2009.

Excerpt "As your storyteller, I am to convey that this tale is set in Jamaica during the last turbulent years of slavery and the early years of freedom that followed."

Emma Donoghue

Room

Written from the perspective of a five-year-old boy who lives with his mother in a locked room in which both are kept captive until they forge an escape plan. The story was inspired by the Josef Fritzl case. Donoghue was born in Dublin in 1969 and her novels include Slammerkin, about an 18th-century prostitute. She lives in Canada.

Excerpt "Today I am five. I was four last night going to sleep in Wardrobe, but when I wake up in Bed in the dark I'm changed to five, abracadabra."

Tom McCarthy

C

The life of Serge Carrefax, who is transfixed by the technologies of the early 20th century. His world becomes darker after he is struck by personal loss in his adolescence. McCarthy has written two previous novels.

Excerpt "Dr Learmont, newly appointed general practitioner for the districts of West Masedown and New Eliry, rocks and jolts on the front seat of a trap as it descends the lightly sloping path of Versoie House."