We should smile at our dogs – a new scientific study reveals why

Photographs of happy, smiling human faces made an area of the brain that is associated with reward "light up" with activity.

Now scientists have worked out exactly what is going on inside a dog's brain when it sees a human - even a complete stranger - smiling or scowling.

This research is building a picture of exactly how thousands of years of living alongside humans has made this possible by moulding and changing dogs' brain circuitry.