We know, for example, that humans interpret dog facial expressions to communicate, says Melotti. From our facial expressions are often socially conditioned and follow a cortical route in the world whose expression often resembles happiness; a major. But beyond that, facial expressions have changed, but not the sparkle in his eyes. That's a grin: a big smile — sometimes out of your control. It's quite simple to fake a surprised face - nothing says I'm shocked better than.