Credit - Photo-Illustration by Chloe Dowling for TIME (Source Images: Klaus Vedfelt—Getty Images, Tim Robberts—Getty Images, Kelvin Murray—Getty Images, Robert Recker—Getty Images, Howard ...

When a baby smiles at you, it's almost impossible not to smile back. This spontaneous reaction to a facial expression is part of the back-and-forth that allows us to understand each other's emotions ...

Humans are social beings, hardwired to navigate complex interactions through signals that communicate our internal states. Of all the channels we use to perceive emotion, the human face is arguably ...

Keira Knightley and Kristen Stewart are its best ambassadors. Instead of curving upwards, their mouths curve downwards, giving them a unique charm. The inverted smile, which doesn't follow the usual ...