WHEN Thomas Malthus, an English economist, in 1798 published his “Essay on the Principle of Population” , quoted above, he caused a sensation. At the time the world’s population was close to 1 billion, having risen slowly and erratically from maybe 300m at the start of the millennium; which in turn was probably not much, if at all, more than it had been in 1AD. And today? Give or take the odd 100m of us, 6 billion.

When Malthus wrote, there was no widespread sense that numbers were running out of control. The general mood was upbeat. Indeed, most thinkers considered a growing population a good thing: more people, more hands at work, more output. 

A century earlier, a pioneer statistician, Gregory King, had predicted that the human race would double from its then total of around 650m in about 600 years’ time, and ventured boldly:

In fact it will do so in about 2006.

By Malthus’s time, a few prophets of doom had begun to give forth. Giammaria Ortes, an Italian economist, wrote in 1790 that no one wanted to see humanity grow

But Malthus’s message was much more urgent than that. Some—probably unrepresentative—American figures gathered by Benjamin Franklin had persuaded him that, unless checked, most populations were likely to double every 25 years, increasing at a geometric rate (1,2,4,8,16 and so on), while food supplies would grow at only an arithmetic rate (1,2,3,4,5 and so on). Sooner or later the food was bound to run out.

Mankind had a choice: either let matters take their course, thus inviting “positive” checks—wars, plagues and famines—to reduce numbers to sustainable levels; or adopt “preventative” checks to ensure fewer children, for example by bridling passion and delaying marriage. Malthus was not optimistic that enough people would choose restraint. He himself tried to set an example by not marrying until he was 38 (and then had three children in quick succession).

Malthus was wrong in expecting populations to double every 25 years. But not far wrong: in the 200 years since he wrote, the time it takes mankind to double has shrunk from several centuries to 40 years. And he was clearly right to note that the earth’s resources are finite, though he vastly underestimated man’s ingenuity in utilising them more efficiently, and at making new inventions. Technology and innovation, speeded up by the industrial revolution, allowed food supplies to increase at a faster-than-arithmetical rate. Even during Malthus’s lifetime, crop land was being expanded rapidly as forests were felled, and innovations such as crop rotation and selective breeding brought large increases in yields. These continue, through the “green revolution” of the 1950s to today’s high-yielding, if unloved, genetically engineered crops.

What Malthus could not have predicted, since nothing like it had ever happened before and it was barely under way by his day, was something known now as the “demographic transition”: the way societies alter as they get richer. First comes a decline in mortality, leading to a short population explosion; then, after an interval of variable length, a steep decline in the birth rate, which slows, halts or may even reverse the rise in numbers.

For most of human history, people had lots of children, of whom many died in infancy. If things were going well, and there were no serious wars, epidemics or famines, more would be born, more would survive longer, and populations would rise. From about 1000 to 1300, Europe enjoyed a spurt of economic growth. A lot of new land was taken into cultivation, and the number of cities multiplied. The population doubled or trebled. 

Enter, in 1347, via the Mediterranean, the Black Death. Within a few years this plague had traversed the continent. By 1400 Europe’s population had shrunk by maybe 25m, about one-third. Plague reappeared periodically over the next three centuries, the last big wave rolling over north-western Europe in the later 17th century, soon after the Thirty Years War, which had already slashed Germany’s population. In the New World, smallpox brought by Spanish conquistadors and European settlers in the 16th century killed maybe 10m-20m of the native populations. Not even the 20th century has escaped such scourges: the worldwide flu of 1918-19 is thought to have caused 25m-40m deaths, far more than the first world war; and since 1980 AIDS has killed some 12m people, so far.

In pre-industrial Europe, frequent food crises also served as periodic population checks. When bad harvests pushed up the cost of grain, more people died and, while the trouble lasted, couples had fewer children. Figures from Tuscany (not alone) in the 16th-18th centuries show grain prices and mortality closely correlated. But by the 19th century the days of famine in Europe were largely over, except in Ireland, where the potato blight of 1846-47 and its side-effects may have killed a sixth of the 8m-odd people.

The transition begins

By the mid-19th century most of Europe was in the first stage of the demographic transition. Mortality had lessened, as wars, famines and epidemics had; local food shortages were rarer, thanks to better economic organisation and transport; public health, medical care (notably, midwifery) and the control of infectious diseases such as cholera and smallpox had improved. The population spurted, as Malthus had predicted. Between 1800 and 1900 Europe’s population doubled, to over 400m, whereas that of Asia, further behind in the demographic transition, increased by less than 50%, to about 950m.

Europe by now was crowded, and most worthwhile land already under the plough. But there was space elsewhere. Thanks to a steady trickle of migration over the previous three centuries, North and South America by 1800 each held about 4m people of European extraction. From around 1850 that trickle became a flood. Over the next 100 years or so, some 50m Europeans quit their continent, most going to North America, others to South America and the Antipodes. At the peak of this wave of emigration, Europe was exporting about a third of the natural increase in its population.

But something else was happening there that would have taken Malthus by surprise: as people came to expect to live longer, and better, they started to have fewer children. They realised they no longer needed several babies just to ensure that two or three would survive. And as they moved from country to town, they also found that children were no longer an economic asset that could be set to work at an early age, but a liability to be fed, housed and (some of them) educated, for years. Worse, with too many children, a mother would find it hard to take and keep a job, to add to the family income. Nor were offspring any longer a guarantee against a destitute old age: in the new industrial society, they were likelier to go their own way.

Thanks to Europe’s new-found restraint, in the past 100 years or so its population has risen only 80%, to 730m, and most countries’ birth rate is now so low that numbers are static or falling. But their composition is very different from the past: better living standards, health and health care are multiplying old heads, even as the number of young ones shrinks.

In contrast, Asia’s population over the same time has nearly quadrupled, to more than 3.6 billion. North America’s too has grown almost as fast, but largely thanks to immigration. Africa’s has multiplied 5 1/2 times, and Latin America’s nearly sevenfold.

Why these differences? From around 1950, mortality in developing countries also began to fall, and much faster than it ever had in Europe. The know-how needed to avoid premature death, especially of small children, travelled so readily that life expectancy in many poor countries is now not far behind the rich world’s. But the attitudes and values that persuade people to have fewer children are taking longer to adjust.

Yet adjust they do. In China, the world’s most populous country, with over 1.2 billion people, and still relatively poor, the demographic transition is already almost complete; not only has mortality come down faster than in other countries with similar income levels, but in recent decades a sometimes brutal population policy (now being relaxed a little) has restricted couples to one or two children. India’s population rushed ahead for longer, and has just reached 1 billion, despite attempts to slow it, including a period in the 1970s when the government promoted large-scale sterilisation. The UN’s “medium-variant” forecast is that by 2050 India’s headcount may be over 1.5 billion, slightly ahead of China’s. Yet in India too fertility has fallen fast. Only in Africa is population growth still rampant, though slowed by AIDS, which in some countries is killing a large proportion of the young adults.

Does more mean worse?

Demographers like to dramatise this recent population growth by asking a spooky question. Of all the people who have ever lived, how many are alive today? The answer requires a lot of guesswork, except for the very recent past; but a fair estimate for the number of people born throughout human history is 80 billion-100 billion. With mankind now numbering 6 billion, the astonishing answer must be: 6-7%. The figures are even more spectacular if you count man-years lived rather than people, because life for early man was usually short: at birth, he could expect 20 years of it in 10000BC, only 27 as late as 1750AD, and 58 today. On that reckoning, those alive today account for one-sixth of the time that humans collectively have spent on earth.

Is all this rise in numbers necessarily a bad thing? Economists have disputed endlessly: does it promote economic growth, by expanding the workforce, or, if it happens too quickly, choke growth off? Their answers seem to boil down to an unhelpful “It all depends.” But then governments’ population policies are not guided solely by economics. Prussia’s Frederick the Great made a sharp political point when he observed in the 18th century that “a country’s wealth is the number of its men.” Two centuries later, Mao Zedong insisted that “China’s vast population should be viewed as a positive asset.”

Of course, numbers are not the only measure. The United States, with its 275m people, has less than 5% of the planet’s population, yet it dominates the other 95%. Still, in many rich countries the birth rate has now fallen so low that the population is actually shrinking; and in some their governments see this as a problem. Their main fear may be that soon there will be too few young workers around to pay for older ones’ pensions. But at the back of their minds there may also be the thought that, say, a Japan of 105m people in 2050 (the UN’s medium forecast) might carry less clout than today’s Japan of 125m.

Many say the globe is already overcrowded, risking environmental disasters such as global warming and pervasive pollution. Nonsense, say others: with careful management it could carry plenty more, say 10 billion. A few optimists, if that’s the word, muse that, with a bit of squeezing and the astute use of technology, the figure might be several times that, maybe even 100 billion.

One thing is sure: even if from tomorrow every couple on earth practised Malthusian restraint and stopped at two children, the momentum built up by the huge population growth in developing countries since 1950 will keep numbers rising fast for decades to come; the UN’s medium forecast for 2050 is 8.9 billion people. But, fingers crossed, soon thereafter even the poorest countries may have lost their enthusiasm for large families, while couples in some richer countries may—may—have rediscovered that two children are, and have, more fun than one. A century or so from now, if mankind survives that long, its number may have reached a new (and surely better) steady state.

Western man is incomparably richer than his ancestors of 1,000 years ago. And he takes it for granted that he will grow richer still. Yet, seen in its long-term context, the past 250 years’ rise in incomes and living standards looks less like an inevitable process and more like a single, astonishing event

FOR nearly all of human history, economic advance has been so slow as to be imperceptible within the span of a lifetime. For century after century, the annual rate of economic growth was, to one place of decimals, zero. When growth did happen, it was so slow as to be invisible to contemporaries—and even in retrospect it appears not as rising living standards (which is what growth means today), merely as a gentle rise in population. Down the millennia, progress, for all but a tiny elite, amounted to this: it slowly became possible for more people to live, at the meanest level of subsistence.

From about 1750, this iron law of history was broken. Growth began to be no longer invisibly slow nor confined, as it largely had been before, to farming. The new increase in human productivity was staggeringly large: it not only supported a hitherto unimaginable 7 1/2-fold rise in the world’s population, but entirely transformed the lives of ordinary people throughout the West.

This surge of growth was due to industrialisation. Thanks to it, material prosperity has risen more in the past 250 years than in the previous 10,000. And so conditioned to growth have people become that most westerners now expect their standard of living to improve automatically year by year; if it does not, something is wrong. This taking for granted what would once have seemed miraculous is the measure of the change.

What, why, there, then?

What happened? And why at that particular time, in that particular place, Western Europe and its American offshoot? The answer to the first question seems straightforward: technology happened. Yes, but that doesn’t tell us much: “better technology” is much the same thing as “economic growth”. The real issue is: why? What set off this technological upheaval, and why there and then?

One theory goes as follows. Technology is driven by knowledge, and especially by scientific knowledge. Knowledge is cumulative: once it exists, it does not cease to exist. So this process of accumulation, with discovery building on discovery, is strongly self- reinforcing, with a built-in tendency to accelerate. When a certain critical mass of knowledge exists, the pace of future accumulation can increase very sharply, as previously unsuspected connections between different branches of knowledge are exploited, each breakthrough creating new opportunities. If something like this is correct, then a technological take-off point was bound to come along somewhere, some time.

Why, then, did it come along in 18th-century Europe? On this view, because the scientific preconditions were in place. European science had flowered in the 17th century—the age of Galileo and Newton, of Hooke and Huygens. These and others, note, were technological innovators as well as scientists. Galileo, a pioneer of mathematics and astronomy, made telescopes and other instruments. Hooke, he of Hooke’s law of the compression and extension of elastic bodies, a brilliant chemist and physicist, built an air pump and developed balance-springs for watches. Huygens, a mathematician and physicist, invented the pendulum clock, and proposed a kind of internal-combustion engine (using gunpowder for fuel); even Newton, generally disdainful of technology, worked on improving the marine sextant and invented the reflecting telescope.

Mathematics and mechanics had come together. By the end of the 17th century, understanding and application had converged. Knowledge had expanded, you might say, up to and beyond that point of critical mass. The intellectual foundations for the technological revolution were in place.

The discovery of atmospheric pressure is probably the best illustration of how an early scientific finding gave rise to a crucial new technology. The technology in question was literally the driving force of the industrial revolution: the steam engine. Evangelista Torricelli and Otto von Guericke were the first Europeans to show that the atmosphere existed; in 1654 von Guericke, mayor of Magdeburg, demonstrated the fact with his famous public experiment in which teams of horses were unable to separate two hemispheres that had had the air between them drawn out. Many others then began to explore the possibilities of harnessing this atmospheric force as a source of power. After more than a century of improvements and iterations, the result was James Watt’s celebrated steam engine, which went into full-scale production in 1774.

This “science leads technology” theory is plausible. Large parts of it are undoubtedly true—yet as it stands it will not quite do.

Central though it may be to the history of the industrial revolution, the case of atmospheric pressure and the steam engine is far from typical. Until the latter part of the 19th century, technological progress did not in general rely on scientific progress. Few of the inventors responsible for the astonishing wave of innovation between 1750 and 1860 were scientists; most were artisans or engineers with little or no scientific training. They were men of common sense, curiosity, energy and vast ingenuity, standing on the shoulders not of scholars but of similarly practical types. Their goal was not to understand, but, as Watt said of his own efforts, to make machines that worked better and (he emphasised) at lower cost. And remember that, for every one who succeeded in this aim, perhaps another hundred tried, at great expense of money and time, only to fail.

This was true across the whole range of 18th-century industries. For about 100 years after 1750, radical innovations in shipbuilding, mining, metallurgy, textiles, food-processing and machine tools were the fruit not of scientific breakthroughs but of indefatigable trial and error, under the guidance of experience and craft tradition. The improvements in cotton-spinning that were soon to transform the British economy—from Arkwright’s spinning machine to Crompton’s mule—had not been waiting upon science. So far as science was concerned, these technologies could have been invented decades or even centuries earlier.

At the start of the 19th century, a Frenchman, Nicolas Appert, found that food could be preserved in bottles that had been boiled and sealed airtight. Within 20 years, tin-coated cans came into use. It was a crucial innovation for the development of urban society. But Appert did not know why his process worked, nor did anybody else; Louis Pasteur did not discover the role of micro-organisms in spoiling food until 1873. First came work, inspiration and luck; later, chemistry.

After 1860 or so, gradually at first and then more rapidly, science began to play a bigger role. Chemistry was indeed the first industrial science. Soon the better understanding of chemical phenomena gave rise to new industrial techniques and, more important, to new materials and entirely new goods. When physics became an industrial science, the results were even more startling: electricity and telecommunications. Thomas Edison, a remarkable pioneer in these fields, was a transitional figure. He was trained as a telegraph operator, not as a scientist. In 1876 he set up his legendary “invention factory” at Menlo Park, New Jersey, began hiring scientists, and set them to solve industrial problems. It was the first industrial research laboratory: the modern pattern was established.

A question of timing

Yet the fact remains that the decisive break between the economic stagnation which kept most of mankind in poverty for thousands of years and the modern era of rapid innovation and growth occurred fully a century before science was harnessed to technology. Moreover, western science had already moved significantly ahead of that of other societies by the beginning of the 17th century; yet the West was no richer at that time than those other societies. It was another 150 years before the real surge in western growth began. The link between science and technology is subtler than you might think.

In its day, ancient Greece was pre-eminent in science. But the knowledge of Aristotle and his students was never applied in the economic realm. The Romans continued that tradition. Far ahead of the barbarians of early medieval Europe, they also established what many today regard as the preconditions for growth in the third world and in the ex-communist economies of Eastern Europe—physical infrastructure and the rule of law. Yet more was achieved in technological innovation during the five or six “dark” centuries after the collapse of the Roman empire than in its heyday. One example: among the most significant innovations of the early Middle Ages was a horse-collar that did not half-throttle the animal as soon as it began to pull with any force. The sophisticated Romans had accepted this handicap, and the flimsy chariots and lack of heavy transport that went with it, for centuries.

But there is a greater puzzle than all this: the course of China’s economic development after 1400. In a different way, this poses an even greater challenge to the view that science and technology move in a virtuous, self-sustaining, naturally accelerating circle.

At the start of the 15th century, China’s supremacy in science and technology alike was dazzling. The economy was on the verge of industrialising. Farming was technologically advanced, using sophisticated hydraulic engineering, ingenious ploughs and other tools, various natural and artificial fertilisers, and carefully documented veterinary medicine. The casting of iron, requiring blast furnaces, began in China before 200BC, in Europe some 1,500 years later.

China invented paper about 1,000 years before the idea reached the West. It was printing by the 8th century, and using a form of movable type by the 11th, four centuries before Johannes Gutenberg got round to it (in a superior, cast-metal, version) in Europe. More mundanely, the Chinese thought of the wheelbarrow in about 200, a fine invention not used in Europe until the 12th century. And that non-throttling horse-collar dreamed up by medieval Europe was in use in China from 250BC. Add in explosives, ship design, clock making, weaponry and so on, and the list seems endless.

Then, after about 1400, China’s technological progress slowed. By 1600 it had fallen behind Western Europe. By 1800 the gap was very wide. It is thought that the Chinese understood atmospheric pressure before the West; but they did not develop the steam engine. The spinning wheel appeared in China about when it did in Europe; but the elaborations that gave Europe the spinning jenny and the industrial production of textiles never followed. In some cases what happened was worse than stagnation: ideas were lost. Su Song’s “great cosmic engine” of 1086—an elaborate water-powered clock, 13 metres high, which tracked time and the positions of the moon and planets—was forgotten by the 16th century.

Science and technology, in short, can get far and then stop. The same happened to Islamic science, which achieved great sophistication up until around 1200, and then came almost to a halt. What happened in Western Europe in the 17th and early 18th centuries that failed to happen in the Western Europe of antiquity, or in China after 1400, or in the Islamic world after 1200?

The question is ferociously debated by economic historians: there is no consensus on the factor that played the single most important role. But there is pretty wide agreement that three broad and overlapping things, between them, made the difference: values, politics and economic institutions.

The bases of progress

Economic growth is a process of economic change. So an appetite for change, or at least a willingness to live with it, is essential if a society is to get richer (except by conquest). This helps to account for China’s falling behind. Its elite valued stability above all. New ideas, especially foreign ones, were suspect. Until the 15th century, the social order could accommodate technological progress reasonably well. The faster and deeper changes required in the early stages of industrialisation were another matter. China’s rulers often blocked change: in the 15th century they ended long-sea trade ventures, choking off commerce and shipbuilding alike.

A readiness for change is only one of the values required. Acquisitiveness is another—an interest in worldly goods, a regard for the material as well as the spiritual, a will to exploit nature for man’s benefit. Yet naked greed is no use. Growth requires investment—and investment is gratification deferred. The enlightened self-interest praised by Adam Smith combines the desire for wealth with prudence and patience.

Growth also requires another kind of selflessness. A modernising society has to move away from self-sufficiency, in individual households, villages, towns, regions and states, towards interaction at all those levels, through specialisation and trade. This in turn demands that enlightened self-interest include an ethical component. Without trust and regard for one’s reputation, the wheels of commerce do not spin.

Altogether, it is an improbable blend. Partly through religion, however, Western Europe developed a system of values that favoured all of the above. Other cultures, it seems, were less conducive to growth. The ruling elites of antiquity, for instance, prized military prowess and intellectual achievement above all; the mundane business of getting and spending was beneath their dignity. China’s rulers, in their own way, were equally uninterested in economic progress.

From time to time, of course, western elites also tried to resist change. But this is where politics comes in. The rulers concerned were always rivals. For the past 1,500 years, no unitary system of control has ever been imposed across Western Europe as a whole. The Roman empire and imperial China stand in marked contrast.

China’s rulers could ban some advance, and their ban was obeyed. Europe’s regimes might try such things. Some did: Florence issued an edict in 1299 forbidding bankers to use Arabic numerals; in 1397 Cologne ordered its tailors not to use machines; after the invention of the ribbon loom in 1579, the city council of Danzig is said to have ordered the inventor to be drowned. But their efforts were in vain, indeed self-damaging: a rule that hurt the economy hurt the state that made it, as against others economically more enlightened. In Europe, rivalry among governments wore away at the interests opposed to economic growth.

In this pluralistic setting, the institutions conducive to growth gradually took shape. Within each state, under a variety of pressures, the economic sphere came to be separated from political control. Magna Carta, which ended the quarrel between King John and his English barons in 1215, established the rights of subjects to their own property, protecting them from the threat of arbitrary confiscation by the crown. It also gave protection to merchants, English and foreign. A new kind of “property right” was recognised for the first time.

Over the next few centuries this slowly nurtured another, no less important, kind of pluralism. A crucial aspect of the separation of politics and economics was that producers (farmers and merchants, in the first instance) kept some of the fruits of their success: the incentive to compete and innovate was in place. In contrast, in China the state long continued to play a central, dominating economic role—and innovators were usually civil servants, with no stake of their own in growth. Arbitrary seizure remained common in the Asian and Islamic worlds; merchants, in effect, were forbidden to get too rich. Yet by replacing arbitrary levies with taxes, western rulers managed to raise more money. As their economies grew, so did the tax base. Law-governed taxation proved to be a better fiscal technology than arbitrary seizure, for rulers and subjects alike.

A host of other innovations followed, extending and refining that fundamental right of property: laws of contract, patents, company law and so on. With time, these allowed a flourishing of many different types of economic enterprise—different in size, ownership and method of organisation. This organisational diversity is the hallmark of the advanced western economies. Here was yet another form of pluralism: just as governments competed, and producers or traders competed, so did different forms of economic organisation. The result was a social framework more effective than any other in history at fostering technological advance.

And so on and on?

Does rapid growth, once started, ever stop? Nuclear war, falling asteroids or man-made environmental catastrophe could all intervene. These risks aside, 250 years of rapid progress is not, in the historical scheme of things, a long period to extrapolate from.

One reason for doubting that growth will roar on and on is that the frontier of technology has moved much closer to the frontier of science; there are fewer wheelbarrows waiting to be invented. On the other hand, the progress of science today seems especially fruitful, technologically speaking: consider the Internet and the prospects for genetic engineering. Values, politics and institutions permitting, the stimulus of competition should flourish yet awhile. If it does, so may the flow of technological advance—and there is no reason why it should not be channelled, for the next 250 years as for the past 250, into improving human lives.