This is a very interesting article that explores the laughter of women, and how and why there was more smiling but less laughing around men. Smiling and laughing represent very different experiences — a smile, especially for a woman, is seen as an act of supplication, where a laugh is often read as a challenge. When we plug in the general, all-purpose smile we signal, effectively, “I’m not looking for trouble. Just be nice to me.”
When we smile that all-purpose smile, many of us look down or in some manner avert our gaze so that we do not make direct eye contact. When you laugh with someone, in contrast, the instinctive response is to look directly into the eyes of the person with whom you share that moment. You’ve connected. You’re standing on the same turf. Laughing together is as close as you can get to a hug without touching.