Sardinian scientists believe they've traced the roots of the 'death-defying' sardonic grin to a plant commonly found on the Italian island.

Greek poet Homer first used the word, an adaptation of the ancient word for Sardininan, to describe a defiant smile or laugh in the face of death.

He was believed to have coined it because of the belief that the Punic people who settled Sardinia gave condemned men a potion that made them smile before dying.