When it comes to sex, the analogies between rats and humans are “profound,” said James G. Pfaus of Concordia University in Montreal. “It’s not simply instinctual for them,” he said. “Rats know what good sex is and what bad sex is. And when they have reason to anticipate great sex, they give you every indication they’re looking forward to it.”
They wiggle and paw at their ears, hop and dart, stop and flash a come-hither look backward.