Peanut butter has roots reaching back to the Aztecs, who mashed roasted peanuts into a paste. However, the modern version was developed in the late 19th century. Marcellus Gilmore Edson of Canada received the first patent for peanut paste in 1884. Later, Dr. John Harvey Kellogg (of cereal fame) patented a process for making peanut butter from steamed peanuts in 1895, marketing it as a protein substitute for people with no teeth. In 1922, Joseph Rosefield developed a process for stabilizing peanut butter using hydrogenated oil, which prevented the oil from separating and allowed it to be stored on shelves without refrigeration. This led to the creation of the Skippy brand. Today, peanut butter is a staple in 90% of American households and a key ingredient in global recipes.