Any dog owner would testify that dogs are just as prone to jealousy as humans.

But can one really compare Othello’s agony to Roscoe’s pique?

The answer, according to Christine Harris, a psychologist at the University of California, San Diego, is that if you are petting another dog, Roscoe is going to show something that Dr. Harris thinks is a form of jealousy, even if not as complex and twisted as the adult human form.

Other scientists agree there is something going on, but not all are convinced it is jealousy. And Roscoe and the rest of his tribe were, without exception, unavailable for comment.

Dr. Harris had been studying human jealousy for years when she took this question on, inspired partly by the antics of her parents’ Border collies. When she petted them, “one would take his head and knock the other’s head away,” she said. It certainly looked like jealousy.