It was my brother’s birthday the other day. I don’t see him very often because we live in different states. So I combed through my archives and found a picture of the two of us when we were small. Goofy blonde grinning idiots, wearing neon sunglasses, hamming it up for Dad’s camera. I posted it on his Facebook page, with a caption about how old we were now.

Afterwards I spent a lot of time staring at that picture, us with our baby-tooth smiles, wrinkle-free and absolutely carefree. And I couldn’t stop smiling right back at us. That’s the thing about smiles, they’re pretty infectious. In fact, research into human behaviour has proved smiling has a whole host of benefits. Here are just a few of them.

1. Research has proved that people cannot help but be affected by other people’s gorgeous smiling faces. Humans take their cues from the people around them, and we like to show understanding by sharing emotions with others, so if you smile at me, I’ll smile right back at you.

Instant mood booster. Image: Giphy.com

2. Looking at that picture of us really boosted my mood, which is another massive benefit of smiling. As much as I hate being told to smile when I’m in a bad mood, it actually can help to do it.

3. Smile scientists (OK, I made that job title up but it is pretty good and I would definitely be one) have found that even a fake smile can cut stress and increase happiness, and the more often you do it, the better off you are – it can actually rewire your brain and train it into thinking positively instead of negatively. Still, I get it, sometimes you just don’t feel like smiling. Sometimes the world is not your friend and everything is terrible and the actual last thing in the world you want is to grin and bear it. Which is totally OK. No one can be happy all the time. That would be weird.

4. Still it’s basically the most recognisable human emotion. I mean, let’s face it, sometimes it can be hard to tell if a person is angry or constipated, but smiling is totally universal. Those smile scientists have looked into this and found that people can identify a smile from up to 90 metres away.

5. And finally, my favourite fact about smiles (as an adult human woman) is that smiles are more attractive than make up, and they use less muscles than frowns (meaning less lines) so they are basically a youth booster to your face without any fancy products required. Win/win.

Sarah-Jane has still got the smiles. Image: supplied.

I thought about all of this while I looked at that picture of my brother and me, and I was left with one overwhelming memory of our childhood. The joy, the laughter and the sheer happiness of it. I couldn’t see the scraped knees, or the huge fights or the many many tantrums about bedtime. I know all that happened, I vaguely remember it, but when I looked at us, and cast my mind back I remembered first, and best, the fun and laughter and the many, many smiles.

Also that time I ran smack into a glass door and bounced backwards onto the floor (thank goodness my Nan’s 70s shagpile carpet was there to cushion my fall).

That’s probably because kids find so much in the world to be joyful about. They smile, on average, 400 times a day. (And then they hit puberty and replace the smiles with eye rolls.) Adults smile around 20 times a day.

No wonder I look back on those early days so fondly.

Get grinning. Image: Giphy.com

When I called my brother later that day to say happy birthday for real, I began as I always do by singing to him as he picked up the phone.

His maniacal booming laugh echoed down the phone at me as I got through to the end of the song, and I was so distracted by it I forgot to sing the traditional “smell like a monkey” version and sang the proper one instead.

So there you go, smiles and laughter can even make you be accidentally extra-nice to your big brother on his birthday. That is some kind of magic.

Sign me up for more of that.

What makes you smile?