根据给定的文本内容，将它分成段落。


文本内容：“Laughter is a physical reaction in humans and some other species of primate, consisting typically of rhythmical, often audible contractions of the diaphragm and other parts of the respiratory system. It is a response to certain external or internal stimuli.”
Laughter is a physical reaction in humans and some other species of primate, consisting typically of rhythmical, often audible contractions of the diaphragm and other parts of the respiratory system. 

It is a response to certain external or internal stimuli.