The Science of Smell

Of all our five senses, smell is the one that people most often forget about. We pay a great deal of attention to what we see and hear, but our sense of smell quietly affects us in many ways without our even noticing. In fact, the human nose can tell apart a surprisingly large number of different smells — far more than most people （ 1 ）.

When we smell something, tiny particles float through the air and enter the nose. There, special cells catch these particles and send signals to the brain. （ 2 ）, these signals travel to a part of the brain that is closely connected with memory and emotion. This is why a single smell — such as fresh bread or rain on a summer day — can suddenly remind us of a place from our childhood, or of a person we have not seen for many years.

Our sense of smell is also important for our safety and health. The smell of smoke can warn us of a fire, and a bad smell can tell us that food has gone bad and should not be eaten. People who lose their sense of smell, perhaps because of an illness, often find that food no longer tastes interesting. （ 3 ） taste and smell work so closely together, losing one of them can completely change the way we enjoy our meals. Scientists are still learning about how smell works, and some companies already use pleasant smells in their shops and hotels to help customers feel calm and relaxed. As this research continues, we may discover even more ways in which this quiet sense quietly shapes our daily lives.