Everything is Golden

I like pineapples, despite their being a complete PITA* to cut up. They’re tart and tangy and a little bit sweet, which is a lovely combination of flavor. They’re even the secret ingredient in every episode of Psych, one of my favorite TV shows, which you can watch here.

But pineapples have their own little secret.

Have you ever noticed that the basket-weave look to a pineapple is just spirals that go in two different directions? Here’s a weird factoid: all pineapples have the same number of spirals. In one direction that number is 8. Guess what the number is in the other direction. Go on. Guess.

What’d you say? If you’re like me, you figured it’s somewhere between 7 and 9.

But it’s not. Its 13.

Don’t believe me? That’s okay. I was told this in my latest nerdy endeavor, which is to watch a series of lectures called The Joy of Thinking: The Beauty and Power of Classical Mathematical Ideas. And I didn’t believe it either.

So, Doubting Thomasina that I am, I went into the kitchen, pulled a whole pineapple out of the refrigerator**, and counted the spirals. Sure enough, there were 8 one way and 13 the other.

Turns out pinecones have 8 spirals one way and 5 the other. Cone flowers have 13 spirals in one direction and 21 in the other. And daisies have 21 spirals in one direction and 34 in the other. Sunflowers have 55 and 89.

Yadda, yadda, who cares, right? Well I do, because I’m nerdy that way.

You may notice that some of these numbers overlap. (Weirdly, so do some of the names, like pine/cone/flower. But that’s neither here nor there.) If you line them up you get 5, 8, 13, 21, 34, 55, 89. This makes a pattern whereby the first two numbers in the series add up to the third number, the second two add up to the fourth number, and so on. So you can extrapolate the series forward and backwards to be 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, etc.

The guy who first noticed this phenomenon and put it all together into a sequence of numbers was Leonardo of Pisa. So in his honor it’s named the Fibonacci Sequence.

Yeah, I don’t get it either.

But Leonardo did this in 1202, when he published a mathematical paper about rabbits propagating. His question was — how many rabbits would you get if you stuck a pair of baby rabbits in a fenced-in area for a year?

Here are the rules: 1) rabbits take two months to mature, 2) after those first two months they will produce a pair of rabbits every month, and 3) we won’t worry about real-life concerns like feeding all these rabbits, cleaning up after all these rabbits, smelling all these rabbits, or freaking out that all of these rabbits are blood relatives and probably genetic mutants.

In January, we’ve got 1 pair of baby rabbits. In February, they reach maturity and we’ve still got 1 pair of rabbits. March, we’ve got a pair of baby rabbits and a pair of adult rabbits, making 2 pair. April, it’s two pairs of adults, 1 pair of babies, for 3 pair. Then it’s 5 pair, 8 pair, 13 pair, on up the Fibonacci sequence until December, when we hit 233 pairs. You can see this idea demonstrated (in a G-rated way) here.

It’s looking like this sequence is repeated in nature quite a bit already, but it goes even farther. And it gets more interesting. I promise.

But I’m tired, so I need to call it a night. More to come later.


*Pain In The Ass

**On a recent visit to a Costa Rican pineapple plantation, my parents learned many facts about how to choose a good pineapple. Among other things, they were told unequivocally to refrigerate the pineapple as soon as they brought it home from the store. So now I do that too.

Categories: Brain Workouts

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