Sniff Out the Facts About Your Sense of Smell

Humans used to get a bad rap for not being good smellers. But recent studies found that our noses can pick up an impressive trillion or more odors. Imagine if they were all at one perfume counter. By comparison, our eyes can only pick out about 10 million colors.

People have 40 million smell receptors. A dog can have as many as 2 billion. But a bear's sense of smell is seven times stronger than a bloodhound's. They use their noses to find food, avoid danger, and locate mates. The killer whale is believed to have no sense of smell at all.

Too many strong smells can make your nose almost go numb. It's called "olfactory fatigue." The same thing happens when you stay in the kitchen for a while. You stop noticing those good smells around you unless you step out of the room and come back.

You're not imagining it. You and your best friend can put on the same scent and it doesn't smell the same. Why? It’s caused by your body chemistry. Everybody's skin is different -- dry or oily, for example -- each with a unique mix of elements like salts, proteins, and hairs. When the chemicals in the perfume react with your skin, you get your own smell.

It’s true. It’s harder to hide the smell of sweat from a woman. When researchers tried to mask body odor with another scent, men’s noses could be fooled 19 out of 32 times. Women were only fooled twice.

Certain smells really can bring back strong memories. Apple pie might remind you of baking with grandma. Chlorine might cause you to recall your first swim lesson. Your sense of hearing doesn't have that same kind of power, say researchers.

Tobacco, as well as medicines like antibiotics and blood pressure pills, can affect how your sniffer works. Sinus problems, a cold or the flu, or a head injury also can have an impact. So can diseases like Parkinson's or Alzheimer's. Some women say their sense of smell gets more intense when they're pregnant.

You may not become so good that you get a job making perfume, but you can sharpen your sense of smell. Here's a tip: Put herbs or spices in containers and mix them up. Sniff gently with your eyes closed. Practice until you get good at identifying the scents.

That's why when you have a cold, food seems really different. How food tastes to you is really the combo of how it tastes and smells. When your nose is stuffed and you can't smell it, your idea of how it tastes is totally changed.

We wake up and smell the coffee. The coffee doesn't wake us up. In the early stages of sleep, some smells might be on our radar. But once we're conked out, smells won't rouse us. That's why people use alarm clocks with sounds -- not smells.