From the restorative powers of chicken soup on a sick day to the warmth of a bowl of chowder on a wintry night, there is no food quite as comforting and emblematic of home as soup. Soup, as Janet Clarkson tells us, is the first true culinary creation of humanity, and it has made a long journey from the prehistoric cave to the kitchen table and the white linens of Michelin-starred restaurants. Tracing its myriad reinventions through history...