Thursday, 31 July 2014


The Girl and I have been working our way through the human story – first hunting and foraging, then breeding edible plants to make crops and taming animals to herd them, then tribes coagulating into larger and larger groups. Tonight, I told The Girl, we’re up to the last several thousand years, and we’re going to talk about empires.

“Yay!” she shouted – “which ones?” She has a tween’s affection for the outrageous, and eagerly consumes stories of Egyptian mummies, Aztec sacrifices and mad Roman emperors.

We’ll start with the earliest and work our way up, I said, but first I want to show you something about every empire ever. Can you draw a timeline, a long line with little marks to represent centuries?

She did so, and said, “What are the years?”

They can be any years, I said – the same thing happened several thousand years ago as happens now. First, do you remember the yeast in the bottle?

She remembered the example well – a single yeast cell was dropped into the bottle at noon, double every minute, and the bottle was full at midnight. She had learned that the bottle was half full not at 6 pm, as seems intuitive, but at one minute to midnight. The bottle was about one per cent full at seven minutes to midnight, and so on.

Do you remember why they multiplied that way? I asked. “Well, they could eat the sugar,” she said.

Right, I said – they found a new resource, and it made them multiply. Do you remember how to draw their growth? I asked.

“Sure,” she said – “It’s exponential.”

Can you draw that kind of curve over the timeline? I asked, and she did, starting with a low straight line right over the timeline and then sweeping upwards.

Good, I said – that’s also what happens when a certain group of humans finds a new resource. Why won’t the exponential growth curve go on forever? I asked.

She looked at me like I was crazy. “Because exponential growth always ends in a die-off,” she said, looking bored; we’ve done that lesson many times.

Well, it has to end somehow, anyway, I said. Can you draw that? I asked, and she drew the rising curve peaking and plunging down again.

Excellent, I said. What you’ve just drawn is an empire. That’s what an empire is.

“What, they multiply like yeast?” she asked.

Maybe not quite so dramatically, I said, but some group of humans finds a new resource, or a way to get an old one, and it lets them grow and conquer everyone else until they can’t grow anymore. Maybe they bred a certain kind of plant into a crop, or tamed a certain animal, or found a new land where the animals never learned to be scared of humans and didn’t run away. It can be a new technology, like the Romans put iron shields together into a phalanx, or like the Vikings developed ships that could brave the far seas. It could be a new religion.

“Wait – what?” she said. “Even if everyone turned to a new religion, they’d use the same energy as before.” Yes, I said, but a religion can change the way people live, and encourage some people to give their lives to a cause, so they’re directing their energy elsewhere.

Thing is, I said, look at the timeline below it – what do you notice?

“It doesn’t take long,” she said, “just a few hundred years.”

It can take longer or shorter, I said, but even if it’s just a hundred years, that’s slow by human standards. Most people who live through the rise or the decline don’t really know it – they see the details of life around them, and not the big picture of what’s happening. Does that make sense?

She nodded thoughtfully, and then asked, “Can we pretend to be people in one of the empires? Like can I be the queen of the Persians, and you be one of the Spartans?”

You can absolutely be queen of the Persians, I said – you don’t want to be a Spartan?

“Not a Spartan woman!” she said. “I don’t want to be kidnapped on my wedding day and shave my head.”

Fair point, I said. Okay, you’re queen of the Persians. We spent the next five minutes sword-fighting with cardboard rolls, until she curled up with a book and was ready for bed. After we had read some more of the Narnia books, I When you’re older, I told her, I want to talk about where we are on that curve.

“Okay,” she said, smiling. “Love you.” 

Photo: The Girl helping me pick up rubbish from the roadside. 

1 comment:

Amy said...

"When you’re older, I told her, I want to talk about where we are on that curve."

That line has haunted me since I read it.