A Brief History of Humans and Food

made by man. All of us eat some raw food, such as fruit and vegetables, but the great majority of food we consume is cooked. Cooking can turn plants that are inedible into edible food by destroying toxic chemicals that plants often manufacture to protect themselves against attack by insects or other herbivorous animals. These toxic chemicals are referred to as “plant secondary compounds” because they are not directly involved in the plant’s normal growth, development, and reproduction, and are produced purely as chemical defenses. They give many of the plants we consume, such as coffee or Brussels sprouts, their bitter taste. Cooked food is often more digestible because heat breaks down tough cellulose cell walls in plants or tough connective tissue in animals. Chewing raw turnip, a plate of uncooked rice, or a raw leg of lamb is much harder work than eating the cooked equivalent. The energy expended in chewing to break down the tough material is replaced by energy from the fuel used in cooking the food, so the ratio of energy gained to energy expended by the body is greater when food is cooked.