Politics & Policy

Welcome, Child Seven Billion

History shows we have nothing to fear from growing population.

This week will see the world’s population reach the 7 billion mark. Not surprisingly, the occasion has excited many declarations from population-control advocates, warning of the danger to us all should such growth continue.

Now, the theory of Thomas Malthus has been used as the scientific justification for anti-human policies from his own time down to the present. But is it true? On the surface, the idea that the more people there are, the less there will be to go around appears to make sense. It therefore follows that if we get rid of some people (especially those we don’t like, anyway), we’ll all be better off. Thus, those interested in eliminating Indians, Irish, Jews, Slavs, Africans, or whomever have been able to argue that their policies, while harsh, are simply necessary to make the world a better place.

Few lies told in the course of human history have been as pernicious, or as false. A look at historical data on the relationships between population growth and living standards demonstrates that the theory of Malthus is at complete variance with the facts.

Let’s begin with Fig. 1, which shows data for world population, global gross domestic product (GDP), and GDP per capita from the year 1 AD down to the year 2000.

Fig. 1 Growth of world population, global GDP, and GDP per capita, from 1 AD to 2000. Note the logarithmic scale. Sources: global GDP (1, 2), world population (12)

This first chart shows that, while human population has certainly increased over time, GDP has increased even more, and the key metric of average human well-being, GDP per capita, has gone up as population has increased, rather than down, as Malthusian theory would predict.

The next chart takes a closer look at the most relevant period — that since the unification of the world economy by the development of long-distance sailing ships around the year 1500.

Fig. 2: Comparison of Malthusian predictions with reality, 1500 to present

In Figure 2, the actual per capita GDP is shown by the thick black line marked with squares. The predictions provided by Malthusian theory, at the time of Malthus’s writing circa the year 1800, are shown with the thin line marked with yellow triangles. According to Malthus, the six-fold increase in population after his time should have resulted in a disastrous drop in human living standards. Instead, global per capita GDP actually increased almost forty-fold, from $179 annually in 1800 to $6,757 by 2000. In short, Malthus was wrong.

Well, everyone has the right to be wrong about predicting the future. But the reader will note that I have taken the liberty of extending Malthus’s prediction into his past. The world population in 1500 comprised 500 million people, just half of that prevailing in Malthus’s day. If living standards go down with increased population, they should go up with decreased population. Thus, according to Malthusian theory, the world should have been much richer in 1500 than it was in 1800, with per capita GDP in the range of $360, instead of the $114 it actually was. Thus Malthus was not just wrong about predicting the future, he was wrong about predicting the past, and not by a small variance, but by a factor of three.

Even more absurd were the predictions based on Malthusian theory widely published by Paul Ehrlich, both alone and together with his protégé John Holdren (currently President Obama’s science adviser) as well as the Club of Rome during the 1968–1972 timeframe.

Writing circa 1970 in works such as The Population Bomb (1968), Population, Resources, Environment (1970), and The Limits to Growth (1972), all of these theorists predicted that the “population explosion” would cause a catastrophic collapse of human well-being by the turn of the century, exactly the opposite of what actually happened. If Ehrlich et al. had been right, average world GDP per capita would have fallen from $3,200 in 1970 to less than $2,000 today. Instead, it rose to over $8,000 by 2010.

This four-fold error in predicting the future was really unforgivable, because Ehrlich et al. had the advantage of hindsight in knowing about the wild inaccuracy of Malthus’s original prediction, which by 1970 had already been shown to be off by a factor of 50 (an actual 18-fold increase in GDP per capita instead of a predicted threefold drop.) But even worse, it is evident that Ehrlich, Holdren, and the Club of Rome studiously ignored data readily available to them about the economic history of the recent past. That is, if one takes the trouble of extending their predictive theory backwards in time (as shown by the thin line marked with exes in Fig. 2), we see that it predicts an average global GDP per capita of over $7,300 for the year 1900 instead of the $670 that it was in reality. Now, Ehrlich was born in the year 1932 (for which his theory predicts an average GDP of $5,700, instead of the $1,060 that it really was). If a wealthy world had actually existed in the less populated 1930s, he should have been able to witness it himself. Instead, within his own lifetime (by 1970), he had seen the world population double and the global standard of living more than triple at the same time. He didn’t even have to open an almanac to know he was wrong. Instead, the data that disproved his theory were readily available to him by direct observation. The same can be said of Aurelio Peccei and his band at the Club of Rome. The first task of any scientist is to compare the predictions of their theory to known data. The fact that Ehrlich, Holdren, and the Club of Rome refused to do this shows that their publications were not science at all, but mere fakery — or less charitably, but perhaps more accurately, pure bunk costumed in pseudo-scientific gibberish for the purpose of justifying an anti-capitalist, anti-development — and ultimately, anti-human — ideology.

So what do the data actually suggest concerning the real relationship between human well-being and population size?

One of the first things any real scientist would do in trying to discover how one variable within a system changes with respect to another is to graph the first variable against the second and see if a clear relationship emerges. Figure 3 follows this tried-and-true technique and graphs world population size and per capita GDP against each other, using the data of the five hundred years of human history.

Fig. 3: How per capita GDP has changed as population has grown, 1500–2010

Well, there certainly seems to be a pattern here, which obviously is not the Malthusian claim that living standards decrease as population grows. Rather, what we see is GDP per capita increasing with population, with a nearly straight-line, direct proportionality holding for the past century. Put another way, the total GDP has risen, not in proportion to the population size, but in proportion to the size of the population squared.

“But that makes no sense!” the Malthusians cry. It doesn’t matter. That’s what the data say, and science is about accounting for reality. So how can we explain the fact that, as the number of human beings on the planet has grown, we’ve nearly all become much better off? Why should there be more of everything to go around, when there are more of us to feed, clothe, and house?

There are a number of very good reasons why this should be so. As economist Julian Simon noted in his indispensible book, The Ultimate Resource, a larger population can support a larger division of labor, so it is more economically efficient. (Simon’s book is the best systematic refutation of Malthusian theory written by anyone, ever. I recommend it strongly.) Ten people with ten skills, working or trading together, can produce far more than ten times as much as one person with one skill. A larger population also provides a larger market that makes mass production and economies of scale possible.

This is extremely important, as we can see by comparing the price of an RL-10 rocket engine with that of a small car. The RL-10, a reliable thruster which has been in production since the 1960s, contains less metal (about 500 pounds) and is significantly less complex than a typical small car. Yet RL-10s sell for around $3 million each, while a new compact car can be obtained for less than $10,000. This is because there is only a market for a few RL-10s per year, while cars are sold by the million. Because they represent a larger market, larger populations drive investment in new plants and equipment much more forcefully than small populations. If the market for an item is small, no one is going to build a new factory to produce it, or spend much money on research to find ways to improve it. But if the sales opportunity is big, the necessary investment will occur instantly as a matter of course. A larger population can much better justify and afford transportation infrastructure, such as roads, bridges, canals, railroads, seaports, and airports, all of which serve to make the economy far more efficient and productive. A larger population can also better afford to build other kinds of highly productive economic infrastructure, including electrification and irrigation systems. It also can better afford the infrastructure necessary for public health, including hospitals, clean water, and sanitation systems, and act far more effectively in suppressing disease-spreading pests. It takes a large-scale effort to drain a malarial swamp, a reality that puts such projects beyond the capability of small highly dispersed populations such as still persist in many parts of Africa. Furthermore, human boots on the ground are necessary to patrol the regions in which we live to prevent ponds and puddles from being used as breeding grounds by mosquitoes and other disease carriers. A thin population will thus in many cases tend to be a much sicker population than a dense population, which enjoys the safety that only numbers can provide against humanity’s deadly natural enemies. And again, a healthy population will be more productive than a sick population, and reap a much better return on the investment it chooses to make in education (and thus be able to afford more education), since more of its young people will live to employ their education, and to be able do so for longer life spans.

That said, it is clear that the actual causative agent for higher living standards is not population size itself, but the overall technological development that it allows. The average living standard is defined by GDP available for consumption per capita, which is equal to the production per capita, which is determined by technological prowess.

If we choose to be mathematical, we could even write this down as an equation. Let L = Living standard, P = Population, G = Gross Domestic Product, and T = Technology. Then we have:

L = G/P           Living standard = GDP/Population  (1)

G = PT         GDP = Population X Technology       (2)

Putting equations (1) and (2) together, we find, simply that:

L = T               Living standard = Technology         (3)

So the question is: What causes the advance of technology? Well, clearly, technology does not come from the land, it comes from people. It is the product of human work. The most general way to measure human work is in terms of person-years. So let’s graph the growth in technology (using GDP per capita as a proxy measure) against human person-years expended, from the year 1 AD to the present. The results are shown in Figs. 4 and 5. (I’ve used two graphs to show this to avoid the necessity of using logarithmic scales, which are harder to read.)

Fig. 4: Growth of technology with respect to person-years, 1 AD to 1875

The growth of human technology worldwide from the time of the Roman and Han Empires to the late nineteenth century basically breaks down into three periods: that before 1500, that from 1500 to 1800, and that after 1800.

From 1 AD to 1500, technology does grow, but only at a very slow rate of 17.5 percent over 460 billion person-years, or an average of 0.035 percent per billion person-years. Between 1500 and 1800, the pace picks up substantially, with GDP per capita increasing by 58 percent in 200 billion person-years, or 0.23 percent per billion person-years, a more than sixfold increase over the preceding period. Then, around 1800, technology takes off, with GDP per capita growing 116 percent over the next 90 billion person-years. As shown in Fig. 5, this growth continues, showing a 4,700 percent increase over the entire 500 billion person-year span from 1800 to 2010, for an average growth rate of 0.8 percent per billion person-years.

Fig. 5: Growth of Technology with respect to person-years, 1400–2010

These results make perfect sense. Before 1500, there really wasn’t a world economy in any substantial sense, because long-distance trade and communication was so limited. Rather than a world economy, what existed was a number of disparate civilizations including European Christendom, the Islamic world, India, China, Mexico, and Peru, each with their own economy. Important innovations made in one civilization could take centuries or even millennia to propagate to the others. Thus, for example, it took hundreds of years for such important Chinese inventions as paper, printing, and gunpowder to reach Europe, and thousands of years for European domesticated horses, wheeled vehicles, and numerous other technologies to reach the Americas. Thus, the relevant inventive population size driving the advance of each civilization was not the whole world population, as small as it was, but the much smaller population of the civilization itself.

But around 1500, following the voyages of Columbus, Vasco de Gama, and Magellan, European long-distance sailing ships unified the world economy, creating vastly expanded markets for commerce, and making it possible for inventions made anywhere to be rapidly implemented everywhere. Thus the effective inventive population for each civilization was radically expanded virtually overnight to encompass that of the entire world, creating a sixfold increase in the rate of progress per person-year compared to that of prior history. With more people engaged, the world advanced faster. Furthermore, it was precisely those countries with the greatest contact with the largest number of people worldwide, i.e., the European seafaring nations, which advanced the fastest.

Then, around 1800, the industrial revolution begins, and the average rate of progress per person-year of human effort quadruples yet again. This occurs not only because the harnessing of steam allowed human beings to wield vastly greater mechanical power than had ever been possible before, but because particular technologies, most notably steamships, railroads, and telegraphs, radically increased the speed and thus the effective range of transportation, commerce, and communication. By the mid-1800s, news about innovations made by anyone, anywhere, could spread around the world virtually instantly, defining a new global reality of accelerated progress that continues to the present day. The fact that any technological advance can now have immediate global impact makes human creativity today far more powerful, and thus valuable, than ever before.

The critical thing to understand here is that technological advances are cumulative. We are immeasurably better off today not only because of all the other people who are alive now, but because of all of those who lived and contributed in the past. If the world population had been smaller in the past than it actually was, we’d be much worse off now. Just consider what the world today would be like if the global population had been half as great in the 19th century. Thomas Edison and Louis Pasteur were approximate contemporaries. Edison invented the electric light, central-power generation, recorded sound, and motion pictures. Pasteur pioneered the germ theory of disease that stands at the core of modern medicine. Which of these two would you prefer not to have existed? Go ahead, choose.

Human beings, on average, are creators, not destroyers. Each human life, on average, contributes towards improving the conditions of human life. This must be so, or our species would long since have disappeared. We live as well as we do today because so many people lived in the past and made innumerable contributions, big and small, toward building the global civilization that we enjoy. If there had been fewer of them, we today would be poorer. If we accept the Malthusians’ advice, and act to reduce the world’s population, we will not only commit a crime against the present, but impoverish the future by denying it the contributions those missing people could have made.

The world needs more people. Child seven billion, welcome aboard.

Dr. Robert Zubrin is president of Pioneer Astronautics, and a member of the Steering Committee of Americans for Energy. His new book, from which this article is adapted, Merchants of Despair: Radical Environmentalists, Criminal Pseudoscientists, and the Fatal Cult of Antihumanism will be published by Encounter Books in February.


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