Valentine’s Day is filled with traditions: flowers, chocolates, and heart-covered cards; but beneath the romance, there’s a world of fascinating mathematics and science hidden in the day. From the geometry of love to evolutionary biology, let’s explore the numbers and theories behind February 14.
1. The mathematics of the heart
Some of you may have encountered the heart-shaped ‘cardioid’ (from the Greek kardia, meaning “heart”). This mathematical shape appears in many contexts, from acoustics to complex numbers.
The equation of a cardioid is:
You can also create a cardioid by taking two equal sized circles, rotating one around the other and tracing the initial point of contact of the circles as it orbits. Pretty cool hey!
2. The dark origins of Valentine’s Day
Many historians believe that Valentine’s Day traces back to the ancient Roman pagan feast of Lupercalia, which was held 13-15 February. Lupercalia was also known as Februa (meaning purging), which gives February its name.
As opposed to chocolates and roses, Lupercalia tended more towards sacrificing goats and running near naked through the streets wearing their bloodied hides to invite fertility.
3. Ka-ching!!!
Nothing says “I love you” like a criminally extortionately priced bunch of roses, grabbed hurriedly from a hawker on the way home on Valentine’s Day. If you think you’re the only sucker out there, fear not.
Globally, over 250 million roses are produced specifically for Valentine’s Day each year, and in Australia, about 5 million blooms are delivered during the Valentine’s Day period.
And, of course, Hallmark & Co. are in on the action. Approximately 145 million Valentine’s Day cards are exchanged annually worldwide, making Valentine’s Day is the second most card-giving holiday, after Christmas.
It all contributes to the $465 million that Aussies splurged on Valentine’s Day gifts in 2024, averaging $135 per person.
While 48% of gift-givers planned to buy flowers, 33% opted for chocolates. I guess that leaves 19% for lingerie, skydiving and dinner (perhaps all 3?).
4. The science of red: Why Valentine’s Day is drenched in this colour
The dominance of red on Valentine’s Day might not be just a marketing trick - perhaps it’s rooted in evolutionary psychology.
We know that in primates, females often display red coloration when they are most fertile, signalling sexual receptivity to males.
And some studies show that men rate women as more attractive and sexually desirable when they wear red compared to other colours.
This subconscious preference is known as the red-attraction effect and has been advanced in multiple psychological experiments, starting with Andrew Elliot and Daniela Niesta in 2008.
However, not all researchers agree on the strength of the ‘red effect’, with some experts questioning the accuracy of the studies and suggesting, among other things, that cultural factors can influence its impact.
5. I love you 'to Infinity and beyond'
Beyond hearts, another romantic mathematical shape is the infinity symbol - often used as a symbol of eternal love. It was way back in 1694 that the great Jakob Bernoulli, who gave us amazing results in everything from calculus to probability first described a special figure-8 shape, which we maths nerds call a lemniscate.
The famous Lemniscate of Bernoulli is the modern-day symbol we use for infinity and it looks a little something like this:
If you’re trying to geek out with your loved one on Feb 14, may I suggest a tattoo of:
Oh well, just an idea.
Anyway, whether you’re plucking up the courage to let someone know you think they are sweet, or, like me, lucky enough to be spending the day with the love of your life; whether you’re going all in on roses, chocolates and jewellery, or like Leah and I thinking “stuff that, how about Netflix and a cuddle”, I hope you have a wonderful Valentine’s Day, and stay tuned for more Nerd Love next week.
That’s all from me for now. If you'd like more geeky fun, please check out my other newsletters below, or connect with me on LinkedIn and/or X.
Yours in nerdiness,
Adam
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