Reddit reviews Laughter: A Scientific Investigation

Robert Provine states that laughter is strictly human. Other animals make similar sounds, but we are the only species that only laugh while exhaling. This control of breath, he argues, is linked to speech ability.

Ah, so that's what the QI stands for. Cool, thanks for sharing, sounds like a worthwhile show to check out. It's on the BBC?

Still I'd want to see this study before I take it to mean anything in particular... most really rigorous data collecting can't be boiled down to half a sentence without oversimplifying so much that the actual meaning is distorted.

edit: ahh. after some obsessive googling, i think the study referred to comes from here.