Human Overpopulation is NOT a Problem – Here’s Why

This article is an excerpt from the Shortform summary of "Factfulness" by Hans Rosling. Shortform has the world's best summaries of books you should be reading.

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Is human overpopulation going to cause massive problems in the world? Will humans reproduce until we run out of resources and room?

The simple answer is NO – human overpopulation is NOT going to be a problem. Let’s go over why, starting with why we read graphs poorly.

Why We’re Wrong About Human Overpopulation

The Straight Line Instinct is the tendency to believe that trends will continue at their current rate forever. Data and some common sense demonstrate that this is not the case:

For example, a child might grow over 35 percent in their first six months after birth, but they obviously don’t continue at this rate for the rest of their lives (otherwise, we would see a lot more seven-foot tall five-year-olds)!

The Straight Line Instinct is the cause of a lot of misplaced pessimism, particularly with regards to world human overpopulation. Magazines, newspapers, and pundits warn of an unsustainable growth in population that will diminish the planet’s food supplies, push climate change past the point of no return, and spark human conflicts as different groups compete for ever-shrinking resources.

(Shortform note: This isn’t a new source of fear. In his 1798 book An Essay on the Principle of Population, the English scholar Thomas Malthus warned that a similar human population explosion threatened to doom his generation to poverty and poverty. Based on what you’ve already learned in this summary, you know that this didn’t happen.)

The idea is widely accepted: 85 percent of surveyed “experts” in Level 4 countries overestimated human overpopulation. And, sure, if you looked at a graph like this, you might be seriously alarmed:

It looks like population is just exponentially growing with no end in sight! Once again, however, popular belief is wrong: population growth is projected to begin leveling off as we approach the end of the 21st century. In fact, the number of children in the world in 2100 is projected to be the same as today.

A Human Overpopulation Problem? Think Again

The world’s population is increasing: but it’s not increasing exponentially and the rate has already begun slowing down. World population will settle between 10 and 12 billion by 2100, a figure far lower than a straight line projection from today’s figure of 7.6 billion would have you believe.

Why will population slow down? Because the number of children will stay flat. One of the benefits of people moving out of Level 1 is that they have fewer children: and indeed, the worldwide average number of babies per woman has halved over the past 50 years. This is because people at Levels 2 and 3 (remember, this is where most of the population now lives) have better access to contraception and less of a need to have children since they don’t need more hands for subsistence agriculture.

As more people leave Level 1 for Levels 2,3, and 4, this will only continue. The trend then starts to become self-sustaining: the new generation of people born at higher income levels will have fewer children than the generation that preceded them. The expected, modest increase in population will come from these children and young adults today growing up and becoming the middle-aged and elderly of the future: there will simply be more adults.

So this is why human overpopulation is not a problem.

It’s useful to put population in some historical context. World population was approximately 5 million during the prehistoric era and stayed flat throughout antiquity and well into the modern era, due to high rates of child mortality. It only reached 1 billion around 1800 as the Industrial Revolution was dawning. Today’s population is around 7.6 billion. The majority of the increase has come only since the mid-20th century.

How the rate of increase is slowing is itself a cause for optimism. People are choosing to have fewer children because they’re rising out of poverty, gaining new economic opportunities, and for women, gaining autonomy of their reproductive choices. It’s a process driven by choice. Contrast that with how population has been held in check for most of human history: child mortality, epidemics, and famine. The new population equilibrium is much better than the old one.

Problems From Worrying About Human Overpopulation

The Straight Line Instinct, when applied specifically to the problem of overpopulation, does real harm to global welfare. If you believe that exponentially growing population is hurtling the planet toward a sustainability crisis, then you would be opposed to investing in healthcare and education services around the world. After all, wouldn’t doing so only exacerbate the problem of overpopulation?

Of course, we’ve learned that the answer to this question is “no.” Lifting people out of poverty is the humane thing to do on its own merits and actually alleviates population growth by bringing people into Levels 2,3, and 4, making them likely to have fewer children. Unjustified fears of human overpopulation have always been used to justify regressive and harmful social policy.

Human Overpopulation is NOT a Problem – Here’s Why

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  • Why we evolved to be negative, and why it's terrible for us today
  • Surprising statistics about how people die - from plane crashes to swine flu
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Allen Cheng

Allen Cheng is the founder of Shortform. He has a passion for non-fiction books (having read 200+ and counting) and is on a mission to make the world's best ideas more accessible to everyone. He reads broadly, covering a wide range of subjects including finance, management, health, and society. Allen graduated from Harvard University summa cum laude and attended medical training at the MD/PhD program at Harvard and MIT. Before Shortform, he co-founded PrepScholar, an online education company.

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