Which Is Worse: Underpopulation Or Overpopulation?

A few decades ago, experts started sounding the  alarm about overpopulation. They were worried because humankind was growing exponentially: we  went from 1 billion people in 1800 to 2 billion people in 1900 to over 5 billion people in  the 1980s. If this trend were to continue, human civilization would run into big problems. 

We'd run out of, well, pretty much everything in just a few decades. But the doomsday scenario  predicted by those experts hasn’t happened, and it isn’t going to. Here’s why.

Hi, I’m David, and this is MinuteEarth. The big thing that has defused our population bomb  is that people just aren't having as many babies as they used to. And that’s happening for two  main reasons.

First, the world’s poorest people are getting less poor. Just a half century ago,  half of the families on earth made less than the equivalent of two US dollars a day. Today only  ten percent make that little.

And it turns out that families that make more than two bucks a day  benefit less from having lots of kids and have more control over how many kids they do have. As a  result, families living above that two bucks a day threshold have, on average, two kids, compared  to the five that poorer families have. That reduction in poverty alone means that the average  family has 1.

3 fewer kids than they used to. Second, women are getting more educated.  Over the last few decades, girls, on average, have gone from attending just 7 years of school  to more than 11.

And it turns out that girls who stay in school longer tend to get married later,  which means they start their families later, which generally means that they have fewer kids. Some  studies have shown that for every four additional years a girl stays in school, she’ll give birth  to one less child than she would have otherwise. Now if you actually do all that math I just  told you you’ll find that the numbers don’t quite add up; the number of babies people are  having isn’t quite as low as a straight-up combination of those two trends would suggest. 

That’s probably because these trends overlap; some of the women who are getting out of poverty  are also becoming better educated, so separating out the effects of each is really messy. We’re not yet at the tipping point where the number of people on Earth is actually  decreasing, but in places where very few people live in extreme poverty and lots  of women are well educated, we’re already seeing populations start to shrink. If these  two trends continue for a few more decades, the planet’s population should follow suit.

So some experts are now sounding the alarm about underpopulation; they’re worried that having  fewer people working and spending money on stuff could blow up the global economy, which could make  as much of a mess as an overpopulation crisis. Other experts, though, think it’s ok if the global  economy shrinks… as long as the global population shrinks faster; after all, that would mean that,  on average, everyone would have more money. We’ll let the experts duke it out over what  might happen in the future.

Either way though, we're not heading towards a population explosion  – which I think we can all agree is the bomb.