It depends on who you ask. As for Mona Lisa and the reason behind her smile, we’ll never know.

There is one thing I know about smiles. They wield power, in a good way. If you offer a genuine smile, it is guaranteed to make the recipient feel better. It’s a fact. In fact, there are a number of fun facts about smiling that most of us probably never contemplated.

Smiling is an innate behavior. We are born knowing how to smile. Ultrasounds have shown babies smiling. Some say those first smiles are just gas. Either way, the muscle power is there without coaching or teaching. As humans, when we are happy or content, we innately raise our lips at the corners, not lower them.

Smiling is universal. It’s demonstrated in the same way from country to country and culture to culture. I could travel to France and though I don’t know a word of French, except for “oui” and “croissant,” I could effectively communicate my happiness with just one smile.

The smile can be traced back over 30 million years of evolution. It likely began as a “fear grin” similar to that of monkeys and apes that use clenched teeth to show predators they are harmless. Dogs demonstrate a similar expression when they’ve done something naughty, like eat a roll of toilet paper, and wish to look submissive to their owners. In humans, this behavior became a signaling system enabling us to communicate information of varying forms.

Scientists tell us there are 19 different types of smiles, but only six are used to communicate levels of happiness. From an all-out wide toothy grin to a suppressed half smile. Smiles that don’t indicate happiness include expressions of misery, fear, embarrassment, nervousness, anger and contempt, to name a few. Further, smiles can be fake, polite or sincere. It sounds complicated, because it is, but humans can easily distinguish one type of smile from another.

Not only that, humans can detect a smile from 300 feet away, that’s a whole football field.

Smiles are contagious. If you see one, you’re more likely to give one. It’s the gift that keeps on giving.

The habit of smiling can increase with practice. Like anything, the more you practice the better you’ll get. But make sure you practice sincere smiles and not fake ones. Fake smiles can be off-putting. You don’t gain friends by dishing out fake smiles.

Children tend to smile more than adults. On average, a child smiles 400 times a day. A very happy adult smiles 40 to 50 times each day, while an average person does so only about 20 times. Maybe we should all try to channel our inner child and smile a little more.

Women tend to smile more than men, in part because it is more socially acceptable for women to smile, at least according to the experts. Women also may be more accurate in detecting emotions and feelings, thereby knowing when and where a smile is warranted and appropriate.

Americans tend to smile more than people in many other countries. In Japan, outward emotions are frowned upon, quite literally, and the Japanese practice smiling with their eyes vs. lips.

Smiling is physically good for you. It boosts your immune system, reduces stress and increases endorphins. Smiling stimulates our brain’s reward mechanisms in a way that even chocolate cannot match. The jury’s still out on wine.

A smile is a nice gesture, but it can be more than just that. A smile has the power to keep someone from feeling invisible. A smile acknowledges another person’s literal being. No one wants to feel invisible. Well, except a bank robber.

Smiling can make the world a happier place. It connects us with other people. And the very act of smiling can make you happier and healthier. It may even lead to laughter. What have you got to lose?

Jill Pertler is an award-winning syndicated columnist, published playwright, author and member of the National Society of Newspaper Columnists. More columns are available at the Slices of Life page on Facebook.