Dogs give the impression of understanding our every word. How well can dogs read our emotions, and can they really smell fear?

Can dogs interpret human emotions? And can they really smell fear? Image credit Alberto … via Flickr

Man – and woman’s – best friend

Anyone who grew up with, or has a pet dog will agree: dogs have an amazing ability to make us feel understood. It’s in the way their eyes study us intently, often with a sympathetic tilt of the head. Dogs tend to stay close when we need comfort and are masters at reading our body language. It’s easy to imagine dogs understand exactly what we feel. But how much is that a case of wishful thinking?

Scientists are still trying to work out exactly how long ago wolves evolved into domesticated dogs, but we know it was tens of thousands of years ago. That’s a long time for humans and dogs to get to know one another. As you’d imagine, there’s been plenty of research into our relationship with man’s best friend. For example, we’ve studied the way dogs respond to our language, voices, body language and emotions. So just how well do dogs understand us?

Reading faces

Dogs are highly tuned to our faces. They use faces to recognise their owners and look particularly to our eyes. Eye-tracking studies show dogs follow our gaze to the same degree as six-month-old babies. Tell your dog not to take a piece of food and then close your eyes. Your dog is more likely to steal the food if your eyes are closed than if you are simply distracted or have your back turned. Worth remembering next time there’s birthday cake on the table.

And just as dogs are tuned into us, dogs have their own facial expressions. We know shelter dogs with a particular facial expression (raised inner eyebrows) are more quickly adopted by new owners. We also know dogs’ faces are more expressive when we pay attention to them. So it’s possible dogs have evolved to use their facial expressions to communicate with us.

But contrary to what you might expect, although dogs’ facial expressions changed when a researcher paid attention to them, dogs didn’t use a cute begging face when there was food around.

Your dog does understand you

Dogs also appear to show empathy; dogs pay more attention to people when they are crying than when they talk or hum. And dogs will sniff, nuzzle and lick a person who is crying, even if that person is a stranger. The fact yawns are contagious has been proposed to be a form of empathy and dogs also ‘catch’ human yawns. Researchers have proposed dogs also have a sense of morality, at least similar to that of babies. One experiment found dogs shun people who won’t help their owners.

Sounds are also important to dogs – they can tell the difference between happy and sad sounds. This research suggested dogs might also ‘catch’ emotions both from humans and other dogs. We also know dogs are able to distinguish between the tone of voice we use and the words we say: researchers scanned dogs brains and found different parts of the brain were involved in processing words and processing how we say those words.

Put sounds and faces together and dogs really stand out in their abilities. A study published last year showed that dogs are the only animals (other than us) able to interpret and recognise emotions from both faces and sounds together.

Can dogs smell fear?

Dogs are renowned for their incredible sense of smell, and it’s commonly said dogs can smell fear. But until recently we didn’t have a lot of evidence.

As part of a recent study, volunteers watched videos designed to make them feel happy, scared or neutral. The researchers then collected samples of these volunteers’ armpit sweat.

Labradors and golden retrievers behaved differently depending on whether they smelled happy or scared sweat. When they were exposed to fear smells, the dogs showed signs of stress. Their heart rates went up, they looked for more reassurance from their owners and were less likely to interact with strangers. But the happy smells made the dogs more likely to approach and interact with strangers – more sociable – and less reliant on their owners.

So dogs are not only able to smell fear, but it appears they may adopt our fear too. No wonder we love them so much.

Links and stuff

• A new origin story for dogs
• Dog brains process speech in the same way we do
• From fearsome predator to man’s best friend