What explains the Polarization of the Globe?

Why are some nations rich and others poor? Why are some powerful and other weak? What explains the roster of great powers? What explains the global distribution of wealth and power? What explains the cross-section of per capita income? Who put the responsibility of the world on the shoulders of the White Man? Who put the Anglo-Saxon in the cockpit of history? Why have all modern great powers hailed from the northern temperate zone? All of these questions can be folded into the question posed in the title of this essay.

There is a sort of consensus among economic historians that the international cross-section of per capita income is roughly a question of the spread of the Industrial Revolution. Countries that industrialized are rich, those that did not are poor. And as countries industrialize they become richer. More precisely, the variation in per capita income is explained by the variation in labor productivity. Countries close the income gap with the rich, industrialized nations when their output per worker catches up with that of the latter; otherwise, they don’t. What needs to be explained then is the cross-section of output per worker. We will return to this question presently.


Figure 1. Source: ILO, author’s computations. We restrict our sample to big countries with populations over 30 million that together account for 4.8 billion of the world’s 7.6 billion people. This excludes all sub-Saharan African countries except Sudan and South Africa.

In the preindustrial world, some places were richer than others but the globe was an order of magnitude less polarized. Living standards were comparable across the core regions of Europe, India, China, and Japan as late as the eighteenth century. Modern standards of living are the result of the Second Industrial Revolution, concentrated in 1890-1940 but extending over 1870-1970, that witnessed the advent and dissemination of key technologies—penicillin, indoor plumbing, electricity, industrial chemistry, and above all, powered machinery. To be sure coal-powered versions of the last were at the center of the cotton textile, steamship and railroad revolutions in Britain in the early-19th century. But mass production with powered machinery did not become generalized well into the 20th century. In either case, the sustained escape from Malthus was the result of a thermodynamic revolution: powered machinery allowed the energy stored in the muscles of man and beast to be supplemented by the energy stored in hydrocarbons. The scale of work that could be performed on the farm and on the factory floor was no longer bounded by the muscle energy of working mammals. And that is what made modern living standards possible; that’s what is responsible for the hockey stick.

The mechanical foundation of modern prosperity raised hopes that that nations that are now poor can industrialize and thereby escape their poverty. Surely there are no insurmountable social or natural obstacles in the acquisition of competence in working with powered machinery? Barriers to cross-border flows of machinery, knowhow, and best-practices are also not insurmountable. Nor certainly is funding; not with the mobilization of modern nation-states. Moreover, low real wages in the poor nations seemingly promise an extraordinary reward to global firms willing to relocate production. Why then has the spread of global industrial production been largely confined to Northeast Asia, Europe, North America, and Oceania? Why have the nations of South America, sub-Saharan Africa, the Middle East, South Asia, Indochina, and Southeast Asia, failed to industrialize before and after independence, and before and after liberalization?

In order to answer this question we have to go to the source of the power. We have to take a closer look at powered machinery. The controlling variable is the (quality-adjusted) rate of production that is achieved by the factory. The secret sauce of powered machinery is the performance of precisely repeated mechanical tasks with great frequency. The repetition is mathematically a harmonic oscillation—the underlying principle of the pendulum. The harmonic oscillator can be thought of as the source of the stability of mechanical movement even at great rapidity. The main difference between the pendulum clock and powered machinery lies in the fact that the rate of the latter is variable and read against the former, even as the former marks the relentless march of time. The game of high productivity is to do this really fast and at scale. It requires clever engineering and factory discipline. More precisely, it requires worker submission to a definite tempo of factory work.

Are the cross-country differentials explained by variation in machinery? or are they explained by the variation in work intensity? In order to disentangle the two we have to look at the cross-country variation in the rate of production with the same powered machinery. That isolates the variation accounted for by factory discipline. What we find in such controlled comparisons is that there is great variation in work intensity—enough to account for the bulk of the gap in output per worker between nations. The breaks are frequent; the machines are left idle for much longer; absenteeism is rife. Even when the worker is at the machine, the pace of work is slower and the work load much lower. Bombay textile workers would mind two spindles in 1920s, where on the same machinery, American workers would mind six. Then as now, in India and across the South, it takes too many workers to do the same amount of work on the exact same machine. Why is that?

We argue that work intensity and factory discipline are functions of the macroclimate of the workers. The globe is polarized the way it is because of the polarization of man’s lifeworld by a merciless sun. Specifically, a harsh sun beats down between the Tropic of Cancer and the Tropic of Capricorn. Work intensity is affected directly by the thermal environment of the factory, as well as indirectly through the epidemiological consequences of the sun’s hostility and the crippling trauma thereby visited upon the inhabitants of the torrid zone. Figure 2 displays two thermal maps of the globe. Left: Number of days of the year the temperature exceeds 20 degrees Celsius. Right: Number of days of the year the temperature exceeds 32 degrees.


Figure 2. Source: Jendritzky and Tinz (2009). Left: days above 20; right: days above 32.

The thermal environment of the factory means frequent breaks are required to cool down. Put simply, work intensity cannot be sustained at the rate of the temperate world with temperatures well beyond the limits imposed by the human thermal balance. Figure 2 shows the maximum temperatures by work intensity recommended by the ISO. Intense work should not be undertaken when the temperature is above 25 degrees Celsius; light work 30 degrees. Above 33 one is at risk of overheating, even if one is at complete rest. In Southeast Asia, Indochina, South Asia, the Middle East, sub-Saharan Africa, and South America, mean temperatures range over 20-40 degrees Celsius. The thermal environment of the factory thus places a sharp and binding limit on the rate and intensity of work performed in a factory.

reference ISO

Figure 3. Source: Kjellstrom et al. (2009).

Not only does the merciless sun make sustained, disciplined factory work incompatible with the human thermal balance, it encourages the proliferation of pathogens, parasites and vectors that sap the strength of the populace of the torrid zone. The mosquito vector, for instance, is endemic to the zone between the January and July 10 degree isotherms displayed in Figure 4. According to the WHO, more than 3.9 billion people in over 128 countries are at risk of contracting dengue, with 96 million cases estimated per year; and malaria causes more than 400,000 deaths every year globally, most of them children under 5 years of age. Other vectors include sandflies, triatomine bugs, blackflies, ticks, tsetse flies, mites, snails and lice.


Figure 4. Source: WHO.

But leading off vectors is misdirected. The issue is not actually vectors but microbial pathology. Germs proliferate luxuriantly in the torrid zone causing a long list of infectious diseases that sap the strength of people already weakened by the scorching sun. Food, culture, behavioral norms, worker behavior are all shaped by the overwhelming need to counter the unrelenting hostility of the heat and the fever. Spicy food, frequent hydration, staying out of the sun, frequent rest, and indeed, minimal physical exertion in the heat—these are adaptations of the people of the torrid zone.

There are limits to human adaptation to the thermal environment. The heat still takes its toll. Childhood infections stunt and cripple the populace. Even people who survive to be healthy adults are periodically put out of action by the deadly germs. But is it reasonable to think that the direct burden of the disease would dominate work intensity on the factory floor? Then how do we make sense of the fact that the strongest correlate of output per worker is the WHO’s measure of per capita years lost to infectious disease?


Figure 5. Source: WHO, author’s computations.

Figure 4 documents the cross-sectional evidence. We have rescaled the observations by per capita income only for visualization; the fit is unweighted. We restrict our sample to 24 countries with more than 30 million people. Together they account for 4.8 billion of the world’s 7.6 billion people. We find that a 1 standard deviation higher infectious disease burden reduces expected output per worker by 0.93 standard deviations with the result that 86 percent of the cross-sectional variation in productivity is explained by the infectious disease burden.

What explains the empirical evidence is the wrath of Ra. The harsh toll of the fever in the torrid zone and efficiency-reducing thermal environment of the factory are both functions of the heat induced by solar radiation. The key to understanding this is to realize that nations are situated animals. They have a specific location on the globe. The zone on which the sun beats mercilessly down on the surface of the earth is a function of latitude that is symmetric across the equator. The distribution of land mass on the surface of the planet is overweight the northern hemisphere; so it comes to us as the ‘north-south’ axis of polarization. But southern Australia, southern New Zealand, the southern trip of Africa are equally pleasant because they too lie in the temperate zone. The gradient of latitude is very significant. But the variable that explains output per worker is the thermal environment. Ra doesn’t need mediators to beat the worker into submission; his wrath is personal; he heats up the worker’s lifeworld himself.

What we have then is a Heliocentric model of global polarization. Given the human thermal balance, the direct effect of solar radiation as mediated by the factory’s thermal environment is sufficient to explain the international cross-section of productivity. Because they are all functions of solar radiation, work intensity, latitude, humidity-adjusted temperature, and disease burden are correlated and priced together into the cross-section of productivity. The controlling variable here therefore is the wrath of Ra.

Ram Rati (1997) has shown that the gradient of latitude explains half the variation in the cross-section of a number of socio-economic variables. Lind (1960) isolated the key problem in his paper titled “The effect of heat on the industrial worker.” See also Axelson (1974) “Influence of heat exposure on productivity.” There is a large physiological literature on heat stress. See Lundgren et al. (2014) for an illuminating case study and in lieu of a literature review.

What is clear is that global polarization is explained by the Heliocentric model. It is telling that the Copernican revolution happened in physiology and not political economy. In the latter discipline, the traditions associated with Malthus, Smith, Marx, and Galton remained trapped in the Latourian rigidity. Who knew that a physiological constraint, the human thermal balance, could bind?

Bandyopadhyaya argued forcefully in Climate and World Order that the macroclimate explained global polarization. He went too far. His remedy called for an intervention to modify the global climate. We have maintained a much more narrow focus in the present study. One clear finding is that air conditioning factories can potentially increase productivity. This should be more carefully investigated via randomized control trials. If they prove as effective as the Heliocentric model suggests, relatively modest investments in air conditioning would have dramatic effects on labor productivity.




One thought on “What explains the Polarization of the Globe?

  1. Albert says:

    Fantastic piece on heat stress & industrial productivity. Will digest & think later but a vignette:
    Scene: biophysics lab at UChicago during undergrad.
    I’m setting up an experiment testing how long zebrafish can swim against a current ( proxy for muscle productivity & oxygen demand) if I vary the temperature between 10C to 35C. It’s a bloodbath around boxes above 25C. Fish literally have heart attacks & jump out of the water rather than stay & swim. Turns out oxygen demand is an exponential function of temperature. Poor bastards didn’t have a chance.

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