We humans are animals, and for all animals, the sense of smell does far more than provide information about a mouthful of food. Smell detects whatever volatile molecules are in the air. It therefore tells an animal about its surroundings: the air, the ground, the plants growing in the ground, other animals moving nearby that might be enemies, mates, or a meal. This more general role explains why we’re sensitive to aroma notes in foods that are reminiscent of the world: wood, stone, soil, air, animals, flowers, dry grass, the seacoast and the forest. It’s also essential for animals to learn from experience, and therefore to associate particular sensations with the situations they accompany. This may be why odors are so evocative of memories and the emotions associated with them.