ACKI LYDEN, HOST:

OK. So here's a joke. A man sitting on the veranda with his wife one night when out of the blue he says: I love you. His wife says: Was that you or was that the beer talking? The man says: That was me talking to the beer. Maybe you found that funny. I find it hysterical. What makes a joke funny is a question that has beset the human condition since we lost our tails and started walking upright.

But, can scientists tell us today why we laugh? Scott Weems is a cognitive neuroscientist and the author of the book, "Ha! The Science of When We Laugh and Why." And he joins us from member station KUAR in Little Rock, Arkansas. Thanks for being with us, Scott Weems.

SCOTT WEEMS: Thank you very much for having me.

LYDEN: Tell me a joke and let's break it down a little bit, would you?

WEEMS: Sure. I should warn you though, as a scientist I'm not trained very well to tell jokes, but I'll do my best.

LYDEN: All right.

WEEMS: So a dog walks in a telegraph office and he says I want to send a message. And the operator says, "Sure what would you like to send?" And the dog says, "Woof woof woof woof woof woof woof woof woof." And the operator pauses a second and goes, "You know, that's only nine. You can send a 10th woof for free." And the dog replies, "But that would make no sense." People never laugh when I tell that joke.

LYDEN: I'm giggling. I'm giggling here.

WEEMS: Thank you. I wouldn't hold it against you if you didn't.

LYDEN: All right. I'm kind of getting my comedy writing sketch part here, but you're a neuroscientist. What makes it funny?

WEEMS: There is one part of the brain that's worth recognizing and it's called the anterior cingulate. It's not on the surface. It's a little below and it's what we consider our conflict detector.

LYDEN: Um-hum.

WEEMS: Anytime we're confused or overwhelmed or just we have conflicting information like in the form of a surprising punch line, this area gets very active.

LYDEN: Why is conflict important in a joke?

WEEMS: It's basically how we process things we don't understand. I mean, so much of our life is filled with conflict, and not just jokes. I mean, people laugh at funerals, people laugh at tragic events, and it's because these are time when we just don't know how else to respond. I mean, humor is much broader than just a standup routine. It's just how we look at these moments in life where things don't make sense.

LYDEN: So laughter is coping, bonding, lessening anxiety, the sense of discovery, surprise; all these things.

WEEMS: It is and I think that's why it's so linked with health benefits as well.

LYDEN: Now, humor hasn't always been looked upon so positively. You write that Plato and Jesus weren't funny.

WEEMS: No. I mean, it's really a shame. Historically, humor has not gotten a good rap. Someone actually counted the number of times that laughter occurred in the Old Testament. The total number is 29 and of those only two are positive. In other words, only two are occasions of joy. Well, there's debates now whether Jesus laughed, not just in the New Testament, but in his whole life.

And, of course, Plato, Hobbs, Nietzsche, these scholars all have very negative views towards humor 'cause they saw it as something that weak minds did. It's not something that serious people do.

LYDEN: Do you think men and women tell jokes differently?

WEEMS: They do. It turns out that women laugh more than men, but they're much less successful in the world if comedy. Or at least there are fewer professional female comedians, which is - it's a shame. And people have wondered why is this? Because it's certainly not that women have less of a sense of humor. And one evolutionary theory is that the men are raised, and maybe even have an evolutionary benefit to being the funny people in relationships.

We men make women laugh because it's a sign of genetic fitness. A man who can make his partner laugh is more likely to be intelligent and a good caregiver. And that's also why women consistently rate sense of humor as No. 1 desired trait in a mate. For men, sometimes it's closer to No. 3, after intelligence and good looks. So women maybe aren't given the benefits and the encouragement to be as funny as they could or should be.

LYDEN: You want leave us with one last joke?

WEEMS: Oh, my. OK, I have had bad success with this in the past but I will give it a try. Two fish are swimming in a tank and one looks to the other and he says: Do you know how to drive this thing?

LYDEN: Scott Weems is a cognitive neuroscientist and the author of "Ha! The Science of When We Laugh and Why." He joined us from Little Rock, Arkansas. Thank you for joining us.

WEEMS: Thank you very much for having me.

(SOUNDBITE OF MUSIC)

LYDEN: And you're listening and maybe laughing to WEEKEND EDITION from NPR News.