For nearly a decade, Vincent Bombail has been tickling rats. It’s been a standard technique used in the study of animal happiness. But not all rats particularly enjoy the experience, data show. Female ...

One study found that rats emitted ultrasonic vocalizations when they were subjected to manual somatosensory stimulation, i.e., tickling. The results of this controversial research were published in ...

If you think laughter and comedy are reserved strictly for humans, you’d be wrong. A study in the late 1990s showed that creatures like rats emit ultrasonic vocalizations while playing with or ...