Proof of how the sun damages your skin

You're looking at the face of a 69 year old truck driver. One side of his face looks much older than the other and this is because for 28 years he's been driving a truck and so one side of his face has been exposed to the sun more than the other. You'd be hard pressed to find a more compelling reason for using sunscreen. The New England Journal of Medicine has published the case study for this condition - which is called Unilateral Dermatoheliosis.