The nose has a microbiome that can help or hinder one's sense of smell.

A bad set of nose microbes can affect mood, cognition, and lifespan.

Regular sniffing strengthens the olfactory bulb and hippocampus, boosting memory and mood.

“Smell is a potent wizard that transports you across thousands of miles and all the years you have lived.”—Helen Keller

A sense of smell is underrated. While we exalt our vision and hearing, smell seems like an optional add-on. But when we sit down to a meal, although we appreciate the sizzle of a fajita or the sight of a beautiful fruit plate, it is the heavenly smell of good food that lifts our mood. Smell brings out the hedonist in us all.

So it’s shocking that almost 20 percent of the population has a poor or non-existent sense of smell. This has an outsized impact on our mood, enjoyment of food, hygiene, social interactions, and even our sex life. Worse yet, it can affect our lifespan. A Swedish study found that olfactory dysfunction—not heart failure, stroke, liver damage, or cancer—is the best predictor of five-year mortality in older adults.

Smell is a deeply primeval sense. Even microbes, which don’t have noses, eyes, or ears, have a way to sniff their environment so they can head away from danger and toward a tasty treat.

As evolution crafted more complicated animals, the sense of smell remained central. The same basic olfactory system is remarkably similar in insects, reptiles, fish, and mammals. It takes a lot of machinery to run the system, with over 400 genes for the various scent receptors. Different odors activate unique combinations of these receptors, yielding a trillion distinct, discernible scents.

Each scent is relayed to the olfactory bulb, and after checking through our........

© Psychology Today