For the past few years, journalist Joel Warner and Peter McGraw, a psychology professor and founder of the Humor Research Lab at the University of Colorado, circled the globe to answer the question: What makes people laugh? They visited comedy clubs in Las Vegas, sat down with cartoonists in Denmark, attended tapings of comedian-helmed game shows in Japan, and explored political satire in Palestine, to name just a few stops along the way. At each locale, Warner and McGraw conducted specific social experiments aimed at unearthing a specific aspect of humor. The results are chronicled in their brand new book, The Humor Code: A Global Search For What Makes Things Funny. Here are some of the duo's most interesting – and funniest – findings.

1. The world's funniest joke is not very funny.
Warner says that in 2001 a British professor launched a campaign to find the world's funniest joke. People all across the world submitted hundreds of thousands of jokes and then the public rated them. The winning joke was about a guy shooting his friend dead. Warner isn't surprised that an unfunny joke was deemed the funniest. "It's never going to be the one that most people find hilarious," he says. "It's the joke the most people find the least offensive. To have mass appeal, it's going to be bland and not very cerebral. That's why you see more generic sitcoms on networks while edgier programs like 'It's Always Sunny in Philadelphia' are on cable, where they don't get as many millions of viewers."

2. You probably don't get Japanese humor.
Warner and McGraw traveled to Japan to look at diversity in comedy. They sat in on a taping of a popular TV game show in which all of the contestants were professional comedians. "We thought that if we could understand their jokes, that would mean humor is common and universal," says Warner. The result? "We did not get their humor at all," he says. However, when Warner and McGraw met the comedians backstage after the taping, even though they spoke completely different languages, "within minutes, we were cracking each other up about penis sizes," Warner says. "This showed us that mass-produced comedy is very culture dependent. But humor in itself is more organic, basic, and therefore universal."

3. Men are not more funny than women – but they try harder.
"Some early research suggested men were funnier than women, but now looking back at those studies, we see they involved sexist humor," Warner says. "Those women probably just didn't laugh at jokes at their own expense. Since then there have been more careful studies, all of which have found that, whether creating or appreciating humor, women and men are far more similar than they are different." Warner says the only real differences between the sexes when it comes to humor involve mating and dating. "Women are looking for a partner with a good sense of humor, while men want someone who laughs at their jokes," he says. This makes sense from an evolutionary and sexual selection standpoint. "Humor is seen as indicator of mental and social intelligence, so it's almost as if guys are showing off their funniness like a peacock to attract a partner," Warner says.

4. Controversy is funny.
According to Warner, places that experience a lot of controversy, turmoil, or hassle – whether it's as serious as civil war or as nonthreatening, but annoying, as riding the crowded New York subway day after day – tend to breed more humor than easy-living oases like, say, Santa Monica or Maui. People joke about these negative facts of life as a way to cope with them, he says. Warner and McGraw trekked to Palestine to test this theory, thinking they'd find lots of humor in this long-embattled area. They did. "Palestine has its own version of 'Saturday Night Live,' which makes fun of President Obama, Osama Bin Laden, and pretty much any public figure," says Warner. "That type of humor is very self-deprecating; it looks at absurdity of the region's situation and laughs at it."

5. Dumb blonde jokes are universal, but only America slams lawyers.
Researchers have tracked the spread of joke cycles – dumb blonde jokes, cracks about different nationalities – in the same way that scientists monitor diseases. They've found that dumb blonde jokes, which first sprang up in the U.S. in the 1950s and '60s when more women were entering the work force, spread quickly to European and South American countries facing the same cultural shifts. But all those jokes about sleazy lawyers that Americans loved telling in the '80s and '90s? They didn't fly outside the U.S. Apparently, according to Warner, no other nations found those funny because no other nation holds law sacred while having such a low opinion of people who practice it.

6. Every nation thinks their culture is the most humorous.
After all their globetrotting, Warner and McGraw weren't able to crown a funniest country. He says the U.S. could be deemed the funniest, but that's only because we're looking at within the American constructs of humor. "My assumption is no matter where you go, the people would say their country is the funniest," Warner says. Same goes for individuals. "When you ask people to self-rate their sense of humor, 90 percent people say they're above-average funny," he says.