The history of peanut butter and jelly began thousands of years ago. Peanuts were discovered by the Incas in 1500 BC and used as food for the afterlife. In 1890, peanut butter was invented by a physician to help patients with digestion. The peanut butter and jelly sandwich became popular in the 1940s as they were included in military rations during World War 2. Jif peanut butter was introduced in 1958 and the world's largest peanut butter and jelly sandwich measured almost 40 feet long and weighed 200 pounds when it was introduced in 1993.