"Please, please, please, just give the dog back," Ellen DeGeneres wept on national TV last week. It was a moment that quickly established itself in the pop culture firmament, less for the plight of Iggy the adopted terrier than for the copious crying itself.

Setting aside the question of whether those sobs were 100 percent genuine, tears are a natural human response, and public figures are obviously not immune. But some who study this most basic expression of feeling will tell you that in this day and age, it can be easier for a crying man to be taken seriously than a crying woman.

In politics, it's a far cry (OK, pun intended) from 1972, when Sen. Ed Muskie's presidential campaign was derailed by what were perceived to be tears in response to a newspaper attack on his wife. Whether he actually cried is still up for debate. But decades later, an occasional Clintonesque tear is seen as a positive thing.

Bill Clinton, that is.

"Bill could cry, and did, but Hillary can't," says Tom Lutz, a professor at the University of California, Riverside who authored an exhaustive history of crying. In other words, the same tearful response that would be seen as sensitivity in Bill could be seen as a lack of control in his wife.

But there are additional rules for acceptable public crying. "We're talking about dropping a tear," Lutz notes, "no more than a tear or two." And it all depends on the perceived seriousness of the subject matter. Thus Jon Stewart or David Letterman could choke up with impunity just after 9/11. But a dog-adoption problem is a whole other matter.

In a recently published study at Penn State, researchers sought to explore differing perceptions of crying in men and women, presenting their 284 subjects with a series of hypothetical vignettes.

What they found is that reactions depended on the type of crying, and who was doing it. A moist eye was viewed much more positively than open crying, and males got the most positive responses.

"Women are not making it up when they say they're damned if they do, damned if they don't," said Stephanie Shields, the psychology professor who conducted the study. "If you don't express any emotion, you're seen as not human, like Mr. Spock on 'Star Trek,'" she said. "But too much crying, or the wrong kind, and you're labeled as overemotional, out of control, and possibly irrational."

That comes as no surprise to Suzyn Waldman, a well-known broadcaster of Yankee games on New York's WCBS Radio.

Earlier this month, she choked up for several seconds on live radio after the Yankees had just been eliminated from the playoffs. She was describing the scene as manager Joe Torre's coaches choked up themselves, watching him at the podium and foreseeing the end of an era.

Her tearful report quickly became an Internet hit, and she was mocked far and wide, especially on radio, with her voice, for example, played over the song "Big Girls Don't Cry."

"This turned into something pretty ugly," Waldman said in an interview. "I don't throw around the word 'sexist,' but this was as sexist as it gets."

She also wrote a passionate editorial in Newsday defending her brief display of emotion. "While the anger and sarcasm that I can and do display is all right with people," she wrote, "the occasional tear is scary and is ridiculed. Why?"

While Waldman notes that female anger in the clubhouse, is OK — it makes her seem tough, she says — one recent study indicates that perceptions of anger, too, differ according to gender.

"When men express anger they gain status, but when women express anger they lose status," Yale social psychologist Victoria Brescoll, who conducted three experiments on how people perceive female anger, said in an interview. Her study is to be published in the journal Psychological Science.

For a little historical perspective, says Lutz, author of "Crying: The Natural and Cultural History of Tears," it's helpful to look back to the 19th century, when skillful politicians like Abraham Lincoln used tears as a natural part of their oratory.

The tide later shifted against male crying, but in the last 30 to 40 years male crying has gained in acceptability. "Every president since Ronald Reagan has used tears at some point," says Shields, the Penn State psychologist.

As for women politicians, many remember the 1987 incident in which Rep. Patricia Schroeder, D-Colo., had to defend herself against charges of weakness after she wept while announcing her decision not to run for president. "I think it's a sign of compassion," she said later.

Military figures have cried at critical moments. Gen. Norman Schwarzkopf cried at a Christmas Eve ceremony in front of his troops, and when interviewed by Barbara Walters, Lutz notes.

There seem to be few limits on crying if you're an entertainment figure. Johnny Carson's tears were touching on the second-to-last night of his career, while serenaded by Bette Midler. As for awards shows, aren't we even a little disappointed (and bored) when a winner DOESN'T cry?

But in DeGeneres' case, along with the strong support from fans and many dog lovers, she also endured some criticism and mockery, especially from fellow comic Bill Maher. (To recap: DeGeneres had adopted Iggy from a rescue organization, then given it to her hairdresser's family when the dog didn't get along with her cats. That was against the rules, and the rescue group took the dog back, prompting her emotional appeal.)

Maher decided to respond on behalf of an entire gender: The opposite one.

"At this moment when the entire nation is saying 'Hmm, can we have a woman president? Maybe they're too emotional,' I don't think this is helping," Maher said on his talk show.

"If I was a woman," he added, "I would be embarrassed right now. I would be embarrassed for all womankind."