It is believed that ladies use a man's ability to make them laugh as a way to judge his genetic fitness as a fitting husband and the prospective father of their children.
The study, which was carried out by Stanford University School of Medicine, comprised of scanning the brains of 22 girls and boys, between the ages of 6 and 13, while they viewed funny videos.
The study found that while watching the humorous clips, girls' brains showed more heightened activity than the boys.
