I looked around. When my eyes reached a corner of the room near the fireplace, he broke into a happy laugh and rubbed his hands together.

VOA: special.2009.07.04

When monkeys get together to kill and eat somebody they make a kind of a laughing noise and chimpanzees laugh when they tickle each other.

猴子一起猎杀其他动物时,它们会发生出一种笑声,黑猩猩胳肢时也会笑。

耶鲁公开课 - 心理学导论课程节选