I'm 70 and I realized my mind stayed sharp not because I'm special, but because I never stopped being curious about things that don't matter — I can tell you about medieval siege warfare and the migration patterns of monarch butterflies, and that randomness is what kept my brain alive

Last month, my neighbor asked me what supplements I take to keep my mind sharp at 70. When I told her "none," she looked at me like I was hiding some secret. Everyone seems to think mental sharpness in old age comes from sudoku, crossword puzzles, or expensive brain-training apps. But after seven decades of living and watching others age around me, I've discovered something different: my mind stayed sharp because I never stopped being fascinated by completely useless things.

Just yesterday, I spent two hours reading about how carrier pigeons navigate using magnetic fields. The day before, I fell into a Wikipedia rabbit hole about the construction of medieval trebuchets. My daughter called while I was deep into an article about why octopi have three hearts, and when she asked what I was doing, I could hear her eyes rolling through the phone.

Why "pointless" knowledge matters more than practical learning

During my 32 years teaching high school English, I watched something interesting happen to my colleagues. The ones who only read within their subject areas, who only learned what was "relevant" to their work, seemed to age faster mentally. Meanwhile, the chemistry teacher who read poetry on his lunch break and the math teacher who studied ancient philosophy stayed vibrant and curious well into their seventies.

When you filter everything through the lens of utility, your brain becomes a specialized tool instead of a playground. You stop making unexpected connections. You stop being surprised by the world. Most importantly, you stop creating new neural pathways because you're always traveling the same mental roads you've worn smooth over decades.

Three years ago, I became obsessed with monarch butterflies. It started when I saw one in my garden and wondered where it was headed. Six library books later, I could explain their four-generation migration cycle, how they use the sun's angle to navigate, and why milkweed is essential to their survival. My grandchildren call it "Grandma's butterfly phase," but that supposedly useless knowledge forced my 67-year-old brain to absorb and synthesize information about something completely foreign to my experience.

The unexpected connections that keep your brain young

Here's what nobody tells you about accumulating random knowledge: it all connects eventually in the most surprising ways. That article about Roman concrete I read last year? It helped me understand resilience when I was writing for my grief support group. Learning about butterfly migration gave me the perfect metaphor when my granddaughter was struggling to find direction after college.

Currently, I'm deep into medieval siege warfare. I can explain the difference between a ballista and a mangonel, tell you why defenders rarely used boiling oil (too expensive – they used water or sand instead), and describe the psychological tactics of a months-long siege. Why does a retired English teacher need to know about battering rams? She doesn't. That's exactly the point.

Every morning at 5:30, I wake up with my tea and deliberately learn something new. Sometimes it's a documentary about octopus intelligence. Sometimes it's an article about the history of punctuation. This morning, I learned how suspension bridges distribute weight. My brain doesn't know these things are "useless" – it just knows it's being asked to stretch, connect, and grow.

How curiosity becomes a shield against cognitive decline

When I cared for my mother through her Alzheimer's, I watched her world shrink until it contained only fragments of memory. It taught me something profound: the brain you have at 70 is largely the one you built at 50, 60, and 65. Every time you choose to learn something new – especially something with no practical application – you're making a deposit in your cognitive reserve account.

After my second husband's Parkinson's diagnosis, I spent the expected hours researching treatments. But I also spent equal time learning about the history of tea cultivation in Ceylon and the physics of soap bubbles. While his body was failing, my mind needed to stretch in unexpected directions to avoid breaking under the weight of watching him fade. That "escapist" learning wasn't running away from reality – it was building the mental flexibility I needed to cope with it.

Studies confirm that lifelong learners have lower rates of cognitive decline, but I don't need research to tell me what I feel. When I push my brain to understand something new – whether it's the lifecycle of stars or ancient Egyptian mummification – I can literally feel those mental muscles working.

The social magic of random expertise

An unexpected benefit of collecting useless knowledge? You become infinitely more interesting at gatherings. When conversation stalls, I can explain why pirates wore eye patches (to maintain night vision below deck) or how the QWERTY keyboard came to be (to slow typing and prevent typewriter jams). But more importantly, it signals that you're still growing, still engaged, still surprised by the world.

My grandchildren seek me out now, not just for grandmotherly advice but because they know I'll have something unexpected to share. When my 22-year-old grandson called about cryptocurrency, I didn't know anything about it. But I said, "Give me a week," and dove in. Not because I'm investing – I'm not – but because understanding how my grandson sees money and value helps me understand him.

When I joined a watercolor class at 66, took up piano at 67, and started baking sourdough at 68, people assumed I was trying to become an artist, musician, or baker. I wasn't. I was challenging my brain to see color differently, to make my fingers and mind work together in new patterns, to understand the science of yeast and gluten. The paintings are terrible, the piano playing is hesitant, and sometimes the bread doesn't rise. But my brain? My brain is thriving.

Permission to wonder without purpose

Somewhere along the way, we're taught that adult learning should be serious and goal-oriented. We study for promotions, read self-help books for improvement, learn new software for efficiency. But what about intellectual play? What about learning for the sheer joy of discovering something you didn't know five minutes ago?

When I tell people I spent an afternoon reading about the architecture of ant colonies or the history of salt, they often look concerned, as if I'm desperately filling empty time. They don't understand that I'm not filling time – I'm expanding it. Every new piece of knowledge makes the world larger, more intricate, more worthy of attention.

The beautiful thing about curiosity is its democracy. The library is free. YouTube University is always open. At 70, I can explore topics that would have required extensive travel or university enrollment when I was young. Last month, I took a virtual tour of the Louvre. This month, I'm learning about mushroom cultivation and the history of jazz. Why? Because I can. Because wondering about things is what keeps us human.

The courage of continued learning

There's a particular vulnerability in admitting ignorance at 70. In sitting in a community center class with people decades younger, struggling with watercolors. In asking your grandchild to explain Minecraft. In starting sentences with "I just learned the most interesting thing..." But that willingness to be a beginner repeatedly is what keeps your mind supple.

I wrote a piece last month about finding purpose after retirement, and I mentioned that the scariest part wasn't losing my identity as a teacher – it was the temptation to stop learning once I stopped teaching. Too many of my peers narrowed their world to the newspaper, medical appointments, and weather reports. Their conversations became loops of the same stories and complaints. They're not unintelligent – they just stopped being curious about things that don't matter.

Final thoughts

Let me leave you with this: honey never spoils. Archaeologists have found 3,000-year-old honey in Egyptian tombs that was still edible. I learned that while researching ancient preservation techniques, which led me to bog bodies, which led to Celtic mythology, which led to comparative folklore, which brought me back to the literature I once taught but now see with completely fresh eyes.

Everything connects if you follow the threads long enough. At 70, I've realized that mental sharpness isn't about being special or doing brain exercises. It's about never stopping that delicious feeling of thinking "I wonder..." and then actually finding out. Not because it's useful, but because wondering and discovering is what makes us feel alive. The medieval siege warfare, the monarch butterflies, the three-hearted octopi – they matter precisely because they don't have to.