Your dog truly 'understands' your smile: Science proves they know exactly how you feel.

In a 2026 study, scientists scanned the brains of 12 awake dogs as they viewed human faces showing happiness, anger, fear and sadness, and found specialized neural activity for smiles while dogs could distinguish fear from anger and sadness. "Humans are really good at picking up small details," said Raúl Hernández-Pérez.