The joke died a lonely death. There was no next of kin to notify, the comedy skit, the hand-buzzer and Bob Newhart's imaginary telephone monologues having passed on long before. But when people reminisce about it, they always say the same thing: the joke knew how to make an entrance. "Two guys walked into a bar"; "So this lady goes to the doctor"; "Did you hear the one about the talking parrot?" The new humor sneaks by on little cat feet, all punch line and no setup, and if it bombs, you barely notice. The joke insisted on everyone's attention, and when it bombed - wow.

"A joke is a way to say, 'I'm going to do something funny now,' " said Penn Jillette, the talking half of the comedy and magic duo Penn & Teller and a producer of "The Aristocrats," a new documentary about an old dirty joke of the same name. "If I don't get a laugh at the end, I'm a failure."

It's a matter of faith among professional comics that jokes - the kind that involve a narrative setup, some ridiculous details and a punch line - have been displaced by observational humor and one-liners. Lisa Lampanelli, who describes herself as the world's only female insult comic, said that in the business, straight jokes were considered "the kiss of death."

"You don't tell joke jokes onstage ever," she said. "Because then you're a big hack."

But out in the real world, the joke hung on for a while, lurking in backwaters of male camaraderie like bachelor parties and trading floors and in monthly installments of Playboy's "Party Jokes" page. Then jokes practically vanished. To tell a joke at the office or a party these days is to pronounce oneself a cornball, an attention hog, and of course to risk offending someone, a high social crime. "I can't remember the last time I was sitting around and heard someone tell a good joke," Ms. Lampanelli said.

While many in the world of humor and comedy agree that the joke is dead, there is little consensus on who or what killed it or exactly when it croaked. Theories abound: the atomic bomb, A.D.D., the Internet, even the feminization of American culture, have all been cited as possible causes. In the academic world scholars have been engaged in a lengthy postmortem of the joke for some time, but still no grand unifying theory has emerged.

"There isn't a lot of agreement," said Don L. F. Nilsen, the executive secretary of the International Society for Humor Studies and a professor of linguistics at Arizona State University.

Among comics, the most cited culprit in the death of the joke is so-called "political correctness" or, at least, a heightened sensitivity to offending people. Mr. Jillette said he believed most of the best jokes have a mean-spirited component, and that mean-spiritedness is out.

"You used to feel safer telling jokes," he said. "Since all your best material is mean-spirited, you feel less safe. You're worried some might think that you really have this point of view."

Older comics tend to put the blame on the failings of younger generations. Robert Orben, 78, a former speechwriter for President Gerald R. Ford and the author of several manuals for comedians, said he believed a combination of shortened attention spans and lack of backbone among today's youth made them ill-suited for joke telling.

"A young person today has a nanosecond attention span, so whatever you do in a humor has to be short," he said. "Younger people do not wait for anything that takes time to develop. We're going totally to one-liners."

"Telling a joke is risk taking," Mr. Orben added. "Younger people are more insecure and not willing to put themselves on the line, so a quick one-liner is much safer."

(Asked if he had a favorite joke, Mr. Orben said, "The Washington Redskins," suggesting that even veteran joke tellers might have abandoned the form.)

Scholars say that while humor has always been around - in ancient Athens, for example, a comedians' club called the Group of 60 met regularly in the temple of Herakles - the joke has gone in and out of fashion. In modern times its heyday was probably the 1950's, but the joke's demise began soon after, a result of several seismic cultural shifts. The first of those, Mr. Nilsen said, was the threat of nuclear annihilation.

"Before the atomic bomb everyone had a sense that there was a future," Mr. Nilsen said. "Now we're at the hands of fate. We could go up at any moment. In order to deal with something as horrendous as that, we've become a little cynical."

Gallows humor and irony, Mr. Nilsen said, were more suited to this dire condition than absurd stories about talking kangaroos, tumescent parrots and bears that sodomize hunters. (Don't know that one? Ask your granddad.)

Around the same time, said John Morreall, a religion professor and humor scholar at the College of William and Mary, the roles of men and women began to change, which had implications for the joke.

Telling old-style jokes, he said, was a masculine pursuit because it allowed men to communicate with one another without actually revealing anything about themselves. Historically women's humor was based on personal experience, and conveyed a sense of the teller's likes and dislikes, foibles and capacity for self-deprecation.

The golden age of joke telling corresponded with a time when men were especially loathe to reveal anything about their inner lives, Mr. Morreall said. But over time men let down their guard, and comics like Lenny Bruce, George Carlin and later Jerry Seinfeld, embraced the personal, observational style.

"A very common quip was, 'Women can't tell jokes,' " Mr. Morreall said. "I found that women can't remember jokes. That's because they don't give a damn. Their humor is observational humor about the people around that they care about. Women virtually never do that old-style stuff."

"Women's-style humor was ahead of the curve," he said. "In the last 30 years all humor has caught up with women's humor."

The mingling of the sexes in the workplace and in social situations wasn't particularly good for the joke either, as jokes that played well in the locker room didn't translate to the conference room or the co-ed dinner party. And in any event, scholars say, in a social situation wit plays better than old-style joke telling. Witty remarks push the conversation along and enliven it, encouraging others to contribute.

Jokes, on the other hand, cause conversation to screech to a halt and require everyone to focus on the joke teller, which can be awkward.

Whatever tenuous hold the joke had left by the 1990's may have been broken by the Internet, Mr. Nilsen said. The torrent of e-mail jokes in the late 1990's and joke Web sites made every joke available at once, essentially diluting the effect of what had been an spoken form. While getting up and telling a joke requires courage, forwarding a joke by e-mail takes hardly any effort at all. So everyone did it, until it wasn't funny anymore.

"The Aristocrats," the documentary produced by Mr. Jillette and the comic Paul Provenza, says a lot about what the straight-up joke once was, and what it isn't any longer. The film, which was shown at Sundance in January and will be released in theaters this summer, features dozens of comics talking about and performing an over-the-top vaudeville standard about a family that shows up at a talent agency, looking for representation.

The talent agent agrees to watch them perform, at which point the family goes into a crazed fit of orgiastic and scatological mayhem, the exact details of which vary from comic to comic. The punch line comes when the agent asks the family what they call their bizarre act. The answer: "The Aristocrats!"

Much of the humor in the documentary comes not from the joke, which nearly everyone in the film concedes is lousy, but from watching modern-day observational comics like Mr. Carlin, Paul Reiser and Gilbert Gottfried perform in the anachronistic mode of Buddy Hackett, Milton Berle and Red Skelton. Imagine watching a documentary of contemporary rock guitarists doing their teenage versions of the solo in "Free Bird" and you'll get the idea; with each rendition it becomes more and more clear why people don't do it anymore.

"Part of the joke is that it's even more inappropriate because we don't do that anymore," Mr. Nilsen said.

One paradox about the death of the joke: It may result in more laughs. Joke tellers, after all, are limited by the number of jokes they can memorize, while observational wits never run out of material. And Mr. Morreall said that because wits make no promise to be funny, the threshold for getting a laugh is lower for them than for joke tellers, who always battle high expectations.

"Jon Stewart just has to twist his eyebrows a little bit, and people laugh," he said. "It's a much easier medium."

Some comics who grew up in the age of the joke say they are often amazed at how easy crowds are in the era of observational humor. Shelley Berman, 79, a comic whose career took off on "The Ed Sullivan Show" and who now plays Larry David's father on the HBO show "Curb Your Enthusiasm," said these days even the most banal remark seemed to get a response.

"I don't tell jokes in my act," he said. "But if I tell an audience I don't tell jokes, I'll get people laughing at that line."

Copyright 2005 The New York Times