Happy faces light up dogs' brains in new study

A study with 14 dogs in brain scanners found that seeing happy, smiling human faces activates the dogs’ reward-related brain circuitry, suggesting positive expressions have intrinsic value for dogs. The researchers note that dogs can distinguish positive emotions from negative ones, though they don’t differentiate among different negative emotions, and argue that domestication shaped dogs’ social brains. The work reinforces the idea that smiling at dogs can be a rewarding way to communicate with them.