"In general, couples who laugh more together tend to have higher-quality relationships,” Kurtz says. "We can refer to shared laughter as an indicator of greater relationship quality."
While it may seem obvious that shared laughter would make for a happier couple, there actually hasn't been a lot of research on laughter's influence on social relations. "Most of the existing work documents laughter’s relevance to individual outcomes or neglects to take the surrounding social context into account," Kurtz says.
Kurtz found that women laughed more frequently than men, but men's laughter is "more contagious." Which is to say... they sound dumber? "When men laugh, they are 1.73 times more likely to make their partner laugh," she says.