Lost in Stagnation - Chapter 2, The Journey of Humanity PDF

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Nova School of Business and Economics

Oded Galor

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Malthusian thesis population growth economic history history of humanity

Summary

This chapter from Oded Galor's book, The Journey of Humanity, details the Malthusian thesis, discussing how population growth can lead to a decline in living standards. It uses historical examples, like the wolves on an island, to illustrate the concept. The chapter also explores the relationship between technological advancement and population growth.

Full Transcript

## Lost in Stagnation The eighteenth-century cleric **Thomas Malthus** was raised in a wealthy family among England's social elite. An influential scholar, he deplored the utopianism of contemporary philosophers such as **William Godwin** and **Nicolas de Condorcet** - luminaries of the Age of Enli...

## Lost in Stagnation The eighteenth-century cleric **Thomas Malthus** was raised in a wealthy family among England's social elite. An influential scholar, he deplored the utopianism of contemporary philosophers such as **William Godwin** and **Nicolas de Condorcet** - luminaries of the Age of Enlightenment - who envisioned humanity's path as one of inevitable progress towards an ideal society. In 1798, Malthus published *An Essay on the Principle of Population*, in which he expressed his profound skepticism about these prevailing and, to his mind, naive views. He advanced the gloomy thesis that in the long run humanity could never prosper because any gains it made would ultimately be depleted by population growth. Malthus had considerable influence on his contemporaries. Some of the most prominent political economists of the period, including **David Ricardo** and **John Stuart Mill**, were profoundly swayed by his argument. **Karl Marx** and **Friedrich Engels**, on the other hand, assailed him for neglecting the role of class-ridden institutions in the prevalence of misery, while the fathers of the theory of evolution, **Charles Darwin** and **Alfred Russel Wallace**, credited his treatise with having a decisive influence on the development of their own highly influential thesis. In retrospect, Malthus's description of the world as it existed in the past was entirely accurate. It was his pessimistic predictions about the future of humanity that turned out to be utterly mistaken. ### The Malthusian Thesis Imagine a village in the pre-industrial age where the inhabitants devise a more efficient method to grow wheat using iron ploughs, considerably increasing their ability to produce bread. At first, the villagers' diets would improve and, trading some of the surplus, their living conditions would rise. The abundance of food might even enable them to reduce their work and enjoy some leisure. But critically, **Malthus** argued, this surplus would allow them to sustain more surviving children, and accordingly the village's population would grow over time. And since the land available for wheat cultivation within the village is necessarily limited, this population growth would gradually lead to a reduction in each villager's bread ration. Living standards would begin to drop after the initial rise and would only stop falling once the ratio of loaves per villager returned to its original level. Painfully, their technological progress would lead to a larger but not a richer population in the long run. This trap has had all living beings in its clutches. Consider a pack of wolves on an island. Global cooling causes sea levels to drop and uncovers a land bridge to another island, which is home to a peaceful population of rabbits. The wolves gain new hunting grounds, the availability of additional prey boosts their living standard, and more cubs survive to reach maturity, leading to an explosion of the wolf population. However, as more wolves must share a limited amount of rabbits, the wolves' living standard gradually reverts to the pre-cooling level, while the wolf population stabilises at a larger size. Access to more resources does not make the wolves better off in the long run. The **Malthusian** hypothesis is based on two fundamental building blocks. The first is that a rise in resources (agricultural yields, fishing hauls, and hunting and gathering bounties) leads populations to have more surviving offspring, driven by the biological, cultural and religious predisposition to reproduce, and the decline in child mortality that accompanies better nourishment. The second building block is that population growth engenders a decline in living conditions whenever living space is limited. According to **Malthus**, the size of any population will adapt to the available resources via two mechanisms: the positive check - a rise in mortality rates due to the increased frequency of famine, disease and war over resources in societies whose populations have outgrown their food production; and the preventative check - a drop in birth rates during periods of scarcity through delayed marriage and the use of contraception. Did technological advancements in the pre-industrial era lead to larger but not richer populations as implied by the **Malthusian** thesis? The evidence is clear that technological sophistication and population size were indeed positively associated in this era, but the existence of this relationship does not in itself indicate an impact of technology on population. In fact, technological advancements during this period were partly the result of larger populations because sizable societies produced both more potential inventors and greater demand for their inventions. Besides, it may be that other independent factors - cultural, institutional or environmental - contributed to the growth of both technology and population, thus accounting for the positive correlation between the two. In other words, this correlation cannot in itself be taken as evidence of **Malthusian** forces. Fortunately, the **Neolithic Revolution** provides us with an intriguing way to test the validity of the **Malthusian** thesis. As argued convincingly by **Jared Diamond**, the evidence strongly suggests that regions that underwent the **Neolithic Revolution** earlier enjoyed a technological head start over their contemporaries which persisted for thousands of years. We can therefore infer a region's level of technological advancement from our knowledge of when it underwent the **Neolithic Revolution** (or from the number of domesticable species of plants and animals in the region). Put another way, at any single point in time, regions that had undergone the **Neolithic Revolution** earlier would be expected to have higher levels of technological sophistication. Thus, all other factors being equal, if a region that underwent the **Neolithic Revolution** earlier is also larger or richer, we can confidently conclude that this has been caused by its level of technological advancement. Using this approach, we can indeed observe the **Malthusian** mechanism at work prior to the industrial era. In 1500 CE, for instance, a higher technological level, as inferred from an earlier onset of the **Neolithic Revolution**, did indeed lead to greater population density, whereas the impact on per capita income was negligible (Fig. 4). Separate evidence, meanwhile, shows that fertile soil also contributed to higher population density but not to higher living standards. And examining even earlier eras through the same lens reveals an impressively consistent pattern - technological advancements and higher land productivity led primarily to larger but not richer populations, implying that prior to the **Industrial Revolution**, people across the world enjoyed largely similar standards of living. ### The Inevitable Onset of Agriculture The **Malthusian** mechanism sheds light on the roots of major events in the course of history that might otherwise appear perplexing. One apparent conundrum is that human remains from early agricultural societies do not attest to improved health or wealth but rather to deteriorating living standards as compared to those of hunter-gatherers living millennia before. Hunter-gatherers evidently lived longer, consumed a richer diet, worked less intensively and suffered fewer infectious diseases. Why, then, did these early farmers and shepherds abandon the relatively bountiful and superior life of hunting and gathering? As described above, the prehistoric humans who branched out of Africa and settled new ecological niches would have enjoyed access to plentiful new resources and would have been able to multiply rapidly without reducing their living conditions. Ultimately, however, in accordance with the **Malthusian** mechanism, this population growth would have balanced out the gains as greater numbers of humans competed for the same stock of wild animals and plants. Living conditions would gradually have reverted to their original subsistence level, despite advances in tools and techniques. In fact, in some societies the decline in living standards, due to excessive population growth, was even worse than a mere reversion and presented the possibility of a societal collapse. This was particularly severe in regions that ancient humans, prior to *Homo sapiens*, had never settled and where the local animals had not adapted to the human threat. In these regions, such as in Oceania and the Americas, the arrival of *Homo sapiens* with their advanced weapons led to such a boom in hunting that it soon brought most large mammals to extinction, forcing the growing number of tribes to compete for resources that were rapidly dwindling. An extreme and dismal example of rapid population growth and over-extraction leading ultimately to collapse can be seen among the isolated Polynesian tribes, such as those who settled **Easter Island** in the **Pacific Ocean** at the beginning of the thirteenth century. For nearly four hundred years, the human population of **Easter Island** expanded rapidly due to the abundance of vegetation and fishing waters. The Polynesians built a flourishing civilisation on the island and sculpted the famous and impressive *moai* statues, the largest of which stands ten metres tall. However, population growth eventually placed increasing pressure on the fragile local ecosystem. By the turn of the eighteenth century, **Easter Island**'s bird population had been wiped out and its forests destroyed, making it harder for the inhabitants to build and maintain fishing boats. The tension this engendered sparked frequent internal conflicts and caused the local population to be decimated by nearly 80 per cent. Similar ecological disasters, described by **Jared Diamond** in his book *Collapse*, occurred on the **Pitcairn Islands** in the **Southern Pacific Ocean**, among Native Americans who settled territories in present-day south-western United States, in the Maya civilisation in **Central America**, and among the Nordic tribes who settled **Greenland**. Hunter-gatherer societies in the **Fertile Crescent** experienced comparable pressure nearly 12,000 years ago. Population growth supported by food abundance and technological improvements prompted a gradual decline in per capita food availability from hunting and gathering until their temporarily enhanced living standards reverted towards subsistence. However, the particular biodiversity of the **Fertile Crescent** with its abundance of domesticable species of plants and animals granted these societies an alternative mode of subsistence that was largely unavailable to the **Easter Islanders** - adopting agriculture. Climatic conditions contributed, too. With the end of the last ice age, around 11,500 years ago, land became more suitable for agriculture and climatic volatility and seasonality increased. Farming thus became a safer strategy of food production, despite being associated with inferior diet quality, than the richer but less predictable and increasingly scarcer one of hunting and gathering. The viability of reliance on agriculture in the **Fertile Crescent** helped avert the ecological crisis that would later destroy the civilisation on **Easter Island**, allowing the region to support a significantly larger population. Indeed, by some accounts, a single acre of land could feed nearly a hundred times more farmers and shepherds than hunter-gatherers. Ultimately, of course, the population size of agricultural societies stabilised at a new and higher level, but this time, in reverting to subsistence level, their living conditions actually became significantly lower than those of hunter-gatherers who had lived millennia before them, when existing ecological niches were not yet densely populated. Compared to the living standards of the hunter-gatherers who were their more immediate ancestors, however, the transition to agriculture was entirely rational, perhaps even inevitable; in fact, it did not reflect a deterioration. Intriguingly, this switch from the bountiful lifestyle of much earlier hunters and gatherers to the impoverished living standards of densely packed farmers may be the origin of the myth of a lost paradise, common to several cultures across the world. With their larger populations and their technological head start, agricultural societies out-competed the hunter-gatherers who remained until eventually agricultural practices became dominant across vast swathes of the globe. A new epoch had begun and there was no going back. ### Population Swings We can also detect the powerful **Malthusian** mechanism at work in the population swings that took place in the era after the **Neolithic Revolution**, triggered by dramatic ecological, epidemiological and institutional upheavals. One of the most devastating events in human history was the **Black Death** - a pandemic of bubonic plague that first erupted in **China** in the fourteenth century and then made its way west with Mongolian troops and merchants as they traveled along the **Silk Road** to the **Crimean Peninsula**. From there it continued its journey on merchant ships to the city of **Messina** in **Sicily** and **Marseilles** in **France** in 1347 and spread like wildfire across the European continent. Between 1347 and 1352 the plague killed 40 per cent of the European population. It was especially lethal in densely populated areas. Within just a few years, many cities - including **Paris**, **Florence**, **London** and **Hamburg** - lost more than half of their inhabitants. Though we can envision the lasting psychological trauma of the **Black Death**, whose survivors lost many of their relatives and friends, the plague did not ravage their wheat fields or flour mills. European farmers were therefore able to resume their work after the terrible devastation and found that demand for their labour had soared. The land desperately needed more working hands, and average labourers soon enjoyed higher wages and better working conditions than they had prior to the **Black Death.** In the years 1345-1500, as the population of **England** collapsed from 5.4 million to just 2.5 million people, real wages more than doubled (Fig. 5). As a result of the improved living standards these wages afforded, birth rates rose and death rates fell, and so the English population slowly started to recover. But in accordance with the **Malthusian** mechanism, that population growth led eventually to a fall in average wages until, within three centuries, both population and wages had reverted to their pre-plague levels. Another momentous population swing followed **Christopher Columbus**'s voyages to the **Americas** in 1492-1504. These continents contained bountiful crops such as cocoa, maize, potatoes, tobacco and tomatoes that were unfamiliar to Europeans, who started shipping them back to Europe. In the opposite direction, crops such as bananas, coffee beans, sugar cane, wheat, barley and rice were brought to the **Americas** for the first time. The potato reached **Europe** in approximately 1570 and quickly became a staple of European cuisine. Potatoes had an especially big impact in **Ireland**, where they became popular among poor subsistence farmers. This crop was particularly well suited to the Irish soil and climate; it boosted farmers' incomes in the short run, and sometimes even allowed them to save enough to buy new livestock. The first peasants to cultivate potatoes enjoyed a significant increase in their calorie consumption and quality of life. In accordance with the **Malthusian** theory, however, this improvement was to be short-lived. In the aftermath of the introduction of the potato, the Irish population swelled from about 1.4 million in 1600 to 8.2 million in 1841, keeping living standards close to subsistence. In fact, the situation was to grow even worse than it had been. In the years 1801-45, numerous parliamentary committees debated the situation; most concluded that **Ireland**'s rapid population growth and collapsing living conditions put it on the brink of disaster, since by then much of the Irish population was entirely dependent on potatoes for its subsistence. Worst of all, it was dependent on a single variety of potato. In 1844, Irish newspapers started reporting that a new fungus - **late blight** - was ravaging potato crops in the United States. The fungus soon reached European ports aboard American cargo ships. From there, it spread to the fields, destroying crops in **Belgium**, southern **England**, **France**, **Ireland** and the **Netherlands**. It is estimated that nearly half of all potato crops in **Ireland** were blighted in 1845 and three-quarters in 1846. The lack of diversity in **Ireland**'s potato crops meant that farmers had no alternative varieties with which to replace their devastated harvests. In the absence of useful intervention or relief from the **British** government, whose policies had encouraged dependency on the single crop in the first place, mass famine became inevitable, and during the **Great Famine** (1845-49) about one million people, mainly in poor rural areas, died from starvation, typhus and diseases that malnourished human bodies were unable to fend off, while more than one million immigrated to **Great Britain** and **North America**. Some areas lost more than 30 per cent of their population. Whole villages were emptied of their inhabitants. Thus, over the course of three centuries, the introduction of a superior crop and its subsequent destruction translated into an increase and then a tragic decline in population size, but living conditions in the long run were largely unaffected. The Europeans were not alone in adopting crops from the New World; the **Chinese** imported sweet potatoes and maize, which were better suited to their soil than potatoes. **Maize** reached **China** in the mid-sixteenth century across three routes: from the north, via the **Silk Road**, which cut through **Central Asia** to the province of **Gansu**; from the south-west, through **India** and **Burma** to the province of **Yunnan**; and from the southeast, aboard Portuguese merchants' ships who traded along the Pacific coast of the **Fujian** province. Initially, maize spread fairly slowly and its cultivation was limited to these three provinces. It gained popularity in the mid-eighteenth century, and by the turn of the twentieth century it had become a staple across the whole of **China**. The adoption of maize had such an impact on the country's agricultural output that **Chinese** researchers later dubbed it their second "agricultural revolution". In many scientific disciplines, controlled experiments enable researchers to determine the impact of a particular factor, such as a novel drug or vaccine, by measuring its effect on an experimental (treatment) group relative to a control group. For historical episodes, however, we cannot wind the clocks back, expose some humans (and not others) to a particular effect, and examine its impact over time. Yet we can draw on quasi-natural historical experiments - historical scenarios that reproduce approximate laboratory conditions, and allow us to infer the impact of a particular factor or event by comparing its influence on the exposed population relative to an equivalent control (unexposed) population. The fact that maize arrived at different times in the different provinces of **China** provides such a quasi-natural historical experiment with which to test the **Malthusian** thesis within a country rather than across countries. According to the theory, we should find that in the long run **Chinese** provinces that adopted maize earlier would end up with greater population densities than those that adopted it later but not with higher income per capita or economic development. However, simply comparing the regions' population densities and living standards is of no use, as provinces that adopted maize earlier may also have had other key differences from the provinces that adopted it later, differences that also affected their population density and living standards. Indeed, **China** as a whole underwent other major transformations during this period that may have influenced regional levels of population density and living standards, independently of the adoption of maize. Instead, scholars have compared the long-term changes in population density and economic prosperity experienced by the first three **Chinese** provinces that adopted maize with those changes in provinces that did not adopt it until much later. Comparing the "differences-in-differences" rather than differences in the actual levels permits us to remove these potentially confounding factors. And indeed, consistent with the **Malthusian** hypothesis, the early introduction of maize in these three **Chinese** provinces resulted in a 10 per cent larger increase in population density than in the other provinces, over the period 1776-1910, and had no apparent impact on wage levels. Overall, the introduction of maize accounts for about a fifth of **China**'s total population growth during this period. It is apparent, then, that neither surpluses nor shortages prevailed indefinitely during the **Malthusian** epoch. The introduction of novel crops or technologies magnified the rate of population growth, mitigating their impact on economic prosperity, while the long-term economic devastation of ecological disasters was ultimately averted by their adverse effects on population via famine, disease and wars. An economic ice age was inevitable. ### The Economic Ice Age The **Neolithic Revolution**, as well as a series of monumental cultural, institutional, scientific and technological advances, had no discernible long-lasting effect on either the economic measure of living standards (per capita income) or the biological one (life expectancy). Like other species, over most of their existence, humans were caught in a trap of hardship and privation, near the subsistence level. Despite some regional differences, income per capita and wages for unskilled labourers in different civilisations fluctuated within only a very narrow band for thousands of years. In particular, estimates suggest that wages for a workday were the equivalent of seven kilograms of wheat grains in **Babylon** and five kilograms in the **Assyrian Empire** more than three thousand years ago, eleven to fifteen kilograms in **Athens** more than two thousand years ago, and four kilograms in **Egypt** under the **Roman Empire**. In fact, even on the eve of their **Industrial Revolution**, wages in Western European countries remained in this narrow range: ten kilograms of wheat in **Amsterdam**, five in **Paris**, and three to four in **Madrid**, **Naples** and assorted cities in **Italy** and **Spain**. Moreover, skeletal remains across various tribes and civilisations over the past 20,000 years indicate that despite some regional and temporary differences, life expectancy (at birth) oscillated within a very narrow band. Remains uncovered in Mesolithic sites in **North Africa** and the **Fertile Crescent** suggest that life expectancy was nearly thirty years. During the subsequent **Agricultural Revolution**, it did not change significantly in most regions, though it dropped in some. In particular, skeletons exhumed from burial sites dating from the early stages of the **Neolithic Revolution**, 4,000 to 10,000 years ago, suggest that life expectancy was about thirty to thirty-five at **Çatalhöyük** (**Turkey**) and **Nea Nikomedeia** (**Greece**), twenty at **Khirokitia** (**Cyprus**), and thirty near the towns of **Karataş** (**Turkey**) and **Lerna** (**Greece**). Two and a half thousand years ago, life expectancy reached about forty years in **Athens** and **Corinth**, but headstones from the **Roman Empire** indicate yet again an age at death in the range of twenty to thirty. More recent evidence points to fluctuations in life expectancy in the range of thirty to forty years in **England** from the mid-sixteenth to nineteenth centuries, and comparable values were recorded in pre-industrial **France**, **Sweden** and **Finland**. For nearly 300,000 years after the emergence of *Homo sapiens*, per capita incomes were scarcely higher than the minimum necessary for survival, plagues and famines were abundant, a quarter of babies did not reach their first birthday, women commonly perished during childbirth, and life expectancy rarely exceeded forty years. But then, as noted earlier, Western Europe and North America abruptly began to witness a rapid and historically unprecedented rise in living standards across various strata of society, a process that was subsequently experienced in other regions of the world. Remarkably, in the period since the dawn of the nineteenth century, a blink of an eye in relation to the Malthusian epoch, per capita incomes soared by a factor of fourteen in the entire world, while life expectancy more than doubled. How did humanity, at last, break free from the grip of the Malthusian forces? The document describes the Malthusian theory and its influence on human history. It also discusses the impact of the Neolithic Revolution and the Black Death on population growth and living standards. The document concludes by asking how humanity was able to break free from the grip of the Malthusian forces. The document includes diagrams and figures. * **Figure 4:** Effects of Technology Level on Population Density and Per Capita Income across Countries in the Year 1500 CE * **Figure 5:** The Impact of the Black Death on Wages and Population in England

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