Human laughter has robust roots in our animalian past, said Jaak Panksepp, a professor of psychobiology at Bowling Green State University in Ohio.

• 研究结果同时表明，笑和喜悦并不只是人类所特有的，早在人类会笑之前，其它一些动物就已经拥有原始形态的笑声了。