My attempt to win $1 million (it’s about population growth)

With the help of a few blondes and a chihuahua, Dick Smith yesterday announced he was going to give away $1 million to someone under thirty who can figure out how to bring our “exponential population growth” under control.

He went further saying: “If we keep growing by 2.1 per cent a year in population, that doubles our population in 30 years, it means in 220 years’ time we would have over one billion people here and no one believes we could feed one billion” (as quoted here).

He has rather insultingly called this prize the Wilberforce award, after the bloke who wanted to end slavery. Yep, end slavery; reduce population growth – definitely on par with each other.

So opportunity knocks for me to make a fortune. Here’s my radical suggestion:

Do nothing.

I’m already planning what to do with my fortune.

Okay, some more detail might be needed.

This could take a while but I’ll say this upfront: there is no chance of Australia reaching a population of 1 billion people.

Here’s part one: Why populations grow.

This is simpler than you might think. It’s really just a case of addition and subtraction. For most of human history the population has either been stable or grown very gradually (certainly not exponentially). In fact, during times of disease and disaster it probably even shrunk a little bit. This occurred because the number births (addition) approximately equalled to the number of deaths (subtraction).

Now obviously this isn’t the case anymore. For the population to grow there must be more additions than there are subtractions. Surprisingly enough, initially it wasn’t the number of additions that changed, but the number of subtractions.

Due to broad improvements in public health, heaps less people were dying. Importantly, this also included babies and children. Before this era (which occurred at different times across the world) a lot of babies were born, but most of them died before their first birthday.

These extra children who survived then made it to be old enough to have kids of their own. And as health continued to improve, their kids also survived and had children. This equals lots of children and a growing population. If everybody has ten kids and they all survive and have ten kids, population will start growing exponentially.

“But wait a minute” I hear you say. “Not everyone is having ten kids these days”. Good point I say, but we’ll come to that in part two.

The other thing that happened at the same time is life expectancy increased (and not just life expectancy at birth, but also in the older age groups). So if everybody suddenly (or gradually, but suddenly is way more dramatic) starts living to 80 instead of 40 you keep a lot more people in the population for a lot longer.

One last note on this part: I’ve only considered population growth on a global scale. At a local level population growth is also affected by migration. Migration can be an addition or a subtraction depending on whether more people enter or leave your country/state/city/town. Migration can have an interesting (and unexpected) effect on population growth depending on who comes and goes – but we’ll discuss that more later.

So in summary: the world population started growing when we figured out that washing our hands was a good idea (or something like that). We all lived longer and had stacks of kids who also had stacks of kids.

Coming up: part two – Who wants babies anyway?