Humans like to think they had a hand in turning wolves into gentle domesticated creatures. Not so, says canine cognition expert Brian Hare. Wolves were domesticated between 15,000 and 25,000 years ago when humans began living in greater density. “We did what we still do today with great alacrity — produce a lot of garbage.”

It was easy pickings. And dogs were particularly interested in human feces. In fact, excrement played a major role in the domestication of dogs. “Think of human feces as like, an energy bar for a wolf,” says Hare. “It’s cooked, digested, it doesn’t run away, and it has more protein than chicken.”

Don’t stare into the eyes of a wolf, warns dog researcher Alexandra Horowitz. “That’s a threat, but dogs have changed from that.” Dogs love to gaze into the eyes of their owners because they get an oxytocin rush. Oxytocin, the hormone that’s produced to encourage bonding with a newborn, is also present in dogs and humans when they make eye contact.

If you and your dog watched a horror movie together, can you tell later in the evening if he’s having a nightmare? Scientists say, unfortunately not. It’s tough to measure whether dogs are counting kibble or running from zombies, says canine scientist Brian Hare. We may not know the content of their dreams, he says, but we know sleep is important. Data show dogs that are getting trained perform better after a good night’s sleep.

Turns out dogs do experience basic emotions like fear, anger, and pleasure. What’s harder to pinpoint is whether canines feel secondary, or more complex, emotions such as guilt. Alexandra Horowitz, psychology professor at Barnard College, created an experiment to find out.

For her guilt test, Horowitz had dog owners enter a room and forbid their dogs to eat a piece of food, and then owners left. If the dog had consumed the treat upon their return, the owner would scold them. If they left the treat alone, the owner would greet them. "I didn’t see more guilty look when the dog was guilty. What I saw was more guilty look when the owner started getting angry.” Her conclusion: the dog didn’t know they violated the rules of the house but they did understand their owner was angry. “[The guilty look] is an expression of appeasement. ‘I’m concerned you look angry and I want to put on this really cute look.’”