Your mouth is more than a smile—it’s a gateway to systemic health. Poor oral hygiene doesn’t just cause cavities; it’s l ...

All smiling involves contraction of the zygomatic major muscles, which lifts the corners of the mouth. But a Duchenne smile is characterised by the additional contraction of the orbicularis oculi ...

But the researchers have found bottlenose dolphins (Tursiops truncates) have an “open mouth” expression that they use to communicate with each other during play, much like a smile in humans.