The science of skin: everything you need to know about your body’s biggest organ – and how to protect it

It is the size of a bedsheet, an outward display of our mood, age and identity and replaces itself completely every month - here's the lowdown on the skin you're in

The Ancient Egyptians knew all about skincare. Scrolls dating back 3,500 years describe elaborate routines to keep the face soft and smooth, the body gently perfumed. If disease and imperfections threatened to spoil the day - and they certainly did in 1550BC - there were treatments on hand for most common ailments: wrinkles and moles, eczema and itches, boils, stings and bites.

How helpful the ancient therapies were is hard to ascertain. But as with the peddling of modern skincare products, it's not clear how much that mattered. Wax, olive oil and fresh milk would swiftly banish wrinkles, one scroll asserts, with the afflicted instructed to See to it!" Unsightly mole? Try berries, grain, honey and leaves crushed in water that has been used to wash the phallus. An itchy neck? A smear of chopped-up bat will heal it at once". But what about that annoying crocodile bite? Slap a lump of meat on it, declares the Ebers papyrus, one of the world's oldest known medical works.