Now that Jennifer Lopez has a boy and a girl, she can report to David Letterman with confidence and experience that men and women's brains are simply different. Mommy science ensues.

Last night on The Late Show, Lopez described how her young son operates: "He's very boy. He's kind of like, lots of energy, runs all over the place, doesn't really think that much. Not to say that men don't think that much!"

After slightly tripping over herself — and Letterman letting her flail, Lopez resolved, "Women in a good way and a bad way think too much sometimes, and men don't!"

No wonder she's made so many romantic comedies.