For thousands of years people thought we had 5 senses, now it's believed we have up to 33. In this ten-part series, philosopher Barry Smith and sound artist Nick Ryan take us on a journey into the extraordinary world of sensory perception.

Today we explore why smell unlocks the door to such vivid memories and emotions. And we discover that training yourself to improve your sense of smell might be better for ageing brains than crosswords and sudoku.

Producer: Melvin Rickarby. Show less