Did We Evolve the Capacity for Sustained Growth?

NOTE: The Growth Economics Blog has moved sites. Click here to find this post at the new site.

I posted a few pieces (here and here) recently on genetics and growth. The Economist even picked up on Justin Cook’s work on lactose tolerance and development. Justin’s work on both lactose and the HLA system are about very specific genes, while the other research I mentioned is about genetic heritability of certain behaviors associated with growth, without specifying any particular genes.

There is another line of research on evolution and growth pioneered by Oded Galor and Omer Moav. They propose that natural selection over different types of individuals could have led to the onset of sustained economic growth. In particular, they focus on selection over preferences for the quantity and quality of kids. This is very much the second kind of research I mentioned above; it does not identify some specific gene that matters for growth, it suggests a mechanism through which selection could have operated. The original paper is linked here, but they have a nice summary article here that explains the logic without all the math.

Let’s be careful about terminology here. Evolution in general requires both mutation and natural selection. GM is really about natural selection, not mutation. They take as given the presence of two types of people in the population. “Rabbits” like to have large families, but do not invest much in their kid’s human capital. “Elephants” have a few kids, but invest a lot in those kids. Their theory is about the proportions of those types change over time due to economic forces, and eventually how a rising prevalence of Elephants leads to a speed-up in technological change. Yes, at some point there must have been a mutation that led to the differentiation between the types, but we can think of that as happening well back in history. They don’t propose that some mutation occurred at some specific year or a specific place to make this all work.

How does the underlying logic work? In the early Malthusian period, with very low income per capita, the Elephants actually have the evolutionary advantage. Why? In the Malthusian world, everyone is so poor that higher income leads to higher fertility no matter your type. Each Elephant kid has high human capital, and thus relatively high fertility compared to Rabbits. So the proportion of Elephants tends to increase in the population. And a higher proportion of Elephants means that average human capital is rising over time.

As the human capital rises, so does the pace of technological progress. At first this doesn’t do much, as the growth of technology is not sufficient to overcome the force of Malthusian population pressure. But eventually there is high enough human capital that technological change happens so rapidly that people reach the upper limit on fertility rates, and choose to spend any additional income on increasing their kids human capital rather than having more kids. This is the tipping point where human capital and technological change go into a virtuous cycle. Higher human capital leads to higher technological change, which leads to higher human capital, etc.. etc.. and you have sustained growth. Once this occurs, the relationship of income and fertility flips to become negative – the richer you are the fewer kids you have, just the opposite of the Malthusian period. This flip in sign is not unique to their explanation based on natural selection, the same type of flip is central to the general unified growth model in Galor and Weil.

After this transition point, the evolutionary advantage also flips to Rabbits. Why? Because the fertility rates decline with income, and as Elephants are richer due to their human capital, they have fewer kids than Rabbits. So Rabbits begin taking up a larger and larger proportion of the population. But everyone is already relatively rich, so this doesn’t mean that human capital levels are low generally. There is sufficient human capital to sustain technological progress.

Do we know if this exact mechanism is what generated sustained growth? No. To establish that you’d have to identify the precise genes that govern preferences for quantity/quality of kids and show that they varied within the population over time in a manner consistent with the GM model. But there are little bits and pieces of circumstantial evidence that work for GM. Greg Clark’s Farewell to Alms documents his research showing that in fact richer families tended to have more kids in pre-Industrial Revolution England. This fits with the selection mechanism proposed by GM. Similarly, Galor and Marc Klemp have a working paper out on the reproductive success of families in 17th and 18th century Quebec (a place and time with particularly detailed records), and the data shows that it was families with moderate fertility rates that actually had the most kids in subsequent generations, not those with the higher fertility rates. Again, it fits the selection mechanism proposed by GM for the Malthusian era.

Note that even if it isn’t true genetic differences in preferences for quantity/quality, you still need to have selection working for population composition to matter for sustained growth. Let’s say that quantity/quality preferences are purely cultural, passed on from parents to kids imperfectly but with some fidelity over time. Then the GM mechanism could still hold up, but it would be the cultural spread of preferences for high quality that generated the take-off, not the spread of specific genes.

There are reasons to be skeptical about this explanation, just as you should be skeptical about any hypothesis. But don’t dismiss it on the basis that natural selection moves far too slowly for this to have mattered for human populations. Galor and Moav have a number of very telling examples regarding the speed of selection within populations over just a few generations. The classic story is peppered moths during the Industrial Revolution. Peppered moths tend to be white, with little black spots on them – hence the name. But there are black varieties. With the rise of coal in the UK black moths became far more prevalent, as they were harder to spot for predators against the blackened sides of buildings. Within a few years the population jumped from predominantly white to predominantly black. And then flipped back to white when clean air regulations came into force. Given the variation in the population already exists, natural selection can take place very quickly to change population composition. So imagining that human population composition could change substantially over hundreds or thousands of years is reasonable.

Last, does GM mean that generating growth in poor countries is doomed to failure because their genetic composition is “wrong”? No. GM is a story about the rise of sustained growth at the global level. Suggesting that poor countries need to get their genetic mix right in order to grow is like suggesting that they need to adopt steam engines and telegraphs before they can step up to gas engines and mobile phones. The question of how to catch up to the frontier is an entirely different question than explaining how we got a frontier in the first place.

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Great Britain and Laissez Not-so-Faire Economics

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I recently finished State, Economy, and the Great Divergence by Peer Vries. It’s a comparison of the activities of the state in Great Britain and China in the period running up to and including the Industrial Revolution, roughly 1650-1850.

Vries critiques the standard view on the role of the state and the divergence between these two places, encapsulating that view in the following:

In the Smithian interpretation of British economic history, that fits in quite neatly with the Whig interpretation of Britains overall history, the primacy of Britain and its industrialization are by and large regarded as the culmination of a long process in which Britains economy increasingly became characterized by free and fair competition and in which government increasingly tended to behave according to Smithian logics.
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For those who endorse them, the predicament of imperial China, that it did not industrialize, has always been quite easy to explain. They only need to refer to the fact that China was characterized by some kind of oriental despotism. This notion has a long pedigree whose beginnings can be traced back at least to Marco Polo.

The alternative that Vries proposes is that China is far more “Smithian” than Great Britain in this period, in the sense that it operated a very hands-off government that mainly served to provide some subsistence insurance to its population, while Great Britain had a relatively large, intrusive, and active government managing its economy and actively interfering in the process of industrialization. With regards to the idea that Great Britain enjoyed a meaningful advantage in institutions (re: property rights) after the Glorious Revolution, Vries has this to say:

I, moreover, see no concrete direct links between changes in property rights and the emergence of modern economic growth during industrialization in Britain, or rather I do not see any major changes in that respect just before and during take off. In several respects property rights in Britain after 1688 were not better protected, as a strengthened central government had acquired more power to interfere with them on the basis of national interest. More in general, one has to realize that, as will be discussed later on, the history of Western Europe was not exactly lacking examples of expropriation and that well protected, entrenched property rights including patents can also be an obstacle to growth.

Vries then spends a good portion of the rest of the book laying out the evidence on government expenditures, taxes, employment, and transfer payments to support the idea that Great Britain had a much more intrusive state than China in this period.

I’ll leave you to the book for the full details, but here are some essential highlights. Taxes per capita in Great Britain were approximately 20 times higher than in China. As a percent of GDP, the figure depends on exactly your preferred source for GDP data, but taxes were again much higher in Great Britain (3-5 times higher depending on the measure). Further, taxes were rising in both per capita and percent of GDP terms over this entire period in Great Britain, while they were essentially flat in China. Finally, the government in China never ran deficits in this entire period. If you are familiar with the history of Great Britain, then you know that government debt as a percent of GDP was essentially zero in 1689, right after the Glorious Revolution. From there it rose steadily, reaching a peak of almost 250% of GDP after the Napoleonic wars. It wasn’t until after 1850 that debt fell back below 100% of GDP. In terms of the number of government officials, Vries cites data that China had between 20,000 and 30,000 civil servants in the 18th century. Great Britain had an equal amount, for a population roughly 30 times smaller. Great Britain spent a much larger fraction of GDP on welfare and poor relief than China ever did.

Drawing on the excellent War, Wine, and Taxes by John Nye, Vries also talks about the attitude of Britain towards free trade:

In the 1820s, for example, the average tariff rate for imported manufactured goods was between 45 and 55 per cent. It was only after 1850, and even then only quite temporarily, that Britain really became a free-trading nation. Overall, its tariffs in the first half of the nineteenth century were so high, higher for example than in France, and continued to be high for so long that any explanation of the first industrial revolution by reference to the existence or emergence of a free-trade economy is extremely improbable. When Britains economy took off, the country definitely was not a free trader in matters of international trade.

Compared to Britain, China was much closer to a free trade nation, declining to interfere or promote imports or exports actively.

Vries wraps up his argument with

This book maintains that the historical evidence now is so heavily in favour of industrial and military policies successfully encouraging long-term economic development in England, admittedly through far more complex means than simply setting tariffs to encourage domestic manufactures, that the burden of proof falls on neoclassical economics, not on the historic record.

Mercantilism, as practiced throughout this period in Great Britain, was not simply a fascination with collecting gold. The British government actively looked to strengthen manufacturing (of imported raw materials) and used military and naval power to open markets with that purpose in mind. To do this it taxed heavily, borrowed heavily, and spent heavily.

What to make of this? There is no necessary link between strict laissez-faire policies and growth. The first industrial nation in the world was anything but laissez-faire, and it intervened far more deeply into its economy than China, which functioned in some sense as the idealized “night watchman” state of Adam Smith. There is little to no evidence that government “just getting out of the way” leads to development. The interventions Great Britain did make certainly resulted in massive monopoly rents to small groups of people at times. So let’s not go overboard in the other direction and conclude that massive state interventions are necessary or optimal. But it is valuable knowing just how un-laissez-faire Britain was during this period.

Why did Britain take off even with all this government interference? Vries doesn’t say this explicitly, but I think his answer is partly that large-scale industrialization has big fixed costs. I want two things before I undertake big fixed investments: a large market and low risk. The British government used the high taxes to fund a military that could ensure large markets around the world, and could ensure that those markets remained open so I could earn enough to pay off my fixed cost. That military (directly or by proxy) could also actively ensure that other markets did not develop competitive industries, again ensuring that I could earn enough to make the fixed costs worth it. Without the market size and low risk, maybe British capitalists are not willing to create the large-scale industries that drove the IR. In that sense, the large size of government was necessary to the industrialization of Britain.

Markets, Institutions, and Underpants

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The title of this post is my proposed re-naming of Sven Beckert’s Empire of Cotton: A Global History. Grabs the attention, right?

The short recommendation is that you should read this book if you are interested in economic history and growth.

The long recommendation is that Beckert’s is an entry in the “global history” genre, this time using cotton production, processing, and trade as the framing device. But it is not just another version of Salt: A World History, with a new commodity plugged in. Beckert actually has a larger point to make about how a “market” in a commodity is something that is created by people, sometimes explicitly and sometimes not. In that sense, this book is better at explaining how institutions shape economies than most books that are specifically about institutions.

A key component of the story is the recognition that the global market for cotton was created prior to the Industrial Revolution, as part of what Beckert somewhat awkwardly calls “war capitalism”. De Gama and Columbus created direct links between Europe, South Asia, Africa, and North America. Europeans then used a superior ability to coordinate firepower and capital to ship goods between these nodes. Cotton from India was sent to Africa for slaves or South-east Asia for spices. The slaves were sent from Africa to North America, the spices to Europe. One could refer to there being “markets” for these things, but only in the sense that Europeans were trading claims on these various people or goods amongst themselves.

Beckert separates the institutions of modern capitalism, which governed the intra-European trade, from the institutions of war capitalism, which governed European trade with non-Europeans. The former developed along the idealized lines of protected property rights, secure contracts, and so forth. The latter was about coercion and expropriation. The Europeans played “cooperate” with each other, so to speak, while playing “deviate” with the rest of the world. In Liverpool the English cotton brokers developed standards of quality, separated physical location in a warehouse from nominal ownership, and created futures contracts. In the American South planters enslaved millions in order to fulfill those contracts.

The consequences of the global market in cotton were far-reaching. The cotton factory, all spindles and chimneys, becomes the epitome of the Industrial Revolution. Beckert’s implied story about innovation in this industry is Allen-like. The major costs of cotton trade were in spinning and weaving, not in growing. So innovation occurs in Britain where those costs are particularly high. But cotton also has far more scope for innovation in processing than the other major crops. It may be natural that cotton production was innovated on. There just isn’t much innovation to do on sugar once it is refined. What are you going to do, make clothes out of it? This isn’t the book to use in an argument about factor prices versus the enlightenment in generating the IR.

The more interesting question that looms over Beckert’s book is whether slavery, or the coercion of labor in any form, was necessary for the growth of the cotton trade and Industrial Revolution. Here you have to be careful about wording. Necessary? No. It was certainly possible that the global cotton trade could have evolved in a different way, perhaps with India and Egypt remaining major exporters and the American South a patchwork of small-holding cotton farmers. But did slavery and the coercion of labor accelerate the development of the global cotton trade and likely the Industrial Revolution? The answer seems to be yes. Ceteris paribus, slavery and coercion made the IR happen sooner rather than later. I think that’s what Beckert would argue. I am leaning towards agreement with him, but I need some more information before I would come down hard one way or the other.

Probably the most compelling thing I learned reading the book is about the layers of institutions that exist within economies. Beckert makes clear that there is no such thing as “English institutions” (or any other) that are constant across all transactions. Institutions are a characteristic of two entities (states, people, firms) and any given pair of entities will have its own set of institutions. So Liverpool and New Orleans cotton brokers had one set of institutions, Liverpool and Manchester brokers had another, while Liverpool and Bombay brokers a third. In some cases those institutions are “good”, fostering cooperation and trust, while others are “bad”, involving coercion. As is typical, institutions are really central to studying growth, but measuring or quantifying institutions without being extremely specific about the exact parties involved is probably hopeless.

Unified Growth Theory is not the Enemy

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In a recent post I compared and contrasted Joel Mokyr’s and Bob Allen’s viewpoints on the origins of the British Industrial Revolution (IR). One failure was to not link to a review paper by Nick Crafts. His is an in-depth review of their two positions, and you should read it.

One of the the themes running through Crafts review is that differences among economic historians in explaining the IR should be set aside (perhaps temporarily) in favor of defending themselves from the real enemy, unified growth theory (UGT). For the uninitiated, UGT is a set of work that develops dynamic models of growth that capture both a period of Malthusian stagnation in output per worker and the take-off to sustained growth. They are concerned with understanding what allows for that transition from stagnation to growth. Oded Galor is the capo di tutti capi of the UGT mafia, and early chapters of his book are an excellent introduction to this literature. I think Chad and I do a good job of giving a low-tech version of UGT in Chapter 8 of our book (you should buy lots and lots of copies).

Full disclosure here. Oded was my dissertation advisor, and I’ve co-authored a paper with him. I have papers of my own that hover around the edge of the true UGT world. So when I proceed to defend this literature below, I am not a neutral 3rd party.

My guess as to why Crafts sets UGT up as the foil to economic history is that UGT takes on big questions while sweeping tremendous amounts of detail under the theoretical rug. The models in UGT are abstract, and while their assumptions may be based on stylized facts drawn from history, they ignore nearly all the nuance that an economic historian would find compelling.

But of course it does that, it’s theory. UGT is not meant to explain the specific instance of the British IR, or any other particular take-off. It is intended to illuminate general forces driving the take-off to sustained growth. Forces that are not obvious from studying James Watts’ personal correspondence or the minutiae of French textile plant accounts.

UGT separates the “Industrial Revolution” from the concept of the take-off to sustained growth. They are not necessarily the same thing, nor do they have to have occurred in any particular order. The take-off to sustained growth is a general economic phenomenon, and the British experience is just one example of it. The British experience happens to make the distinctions very clear. The IR is traditionally date to the late 1700’s but there is a robust literature arguing that sustained growth did not begin in Britain until well into the mid-1800’s (see Crafts and Harley, 1992 on output growth, see Allen for a more recent evaluation of the wage literature).

To wildly over-simplify, the IR is the onset of a specific package of technology that (depending on the author) includes some combination of the following: inorganic power sources, mechanization of tasks, large scale enterprises, institutions supporting innovation, urbanization, the expansion of finance, the expansion of trade, and [fill in whatever I missed]. Growth in wages or output per worker is one other feature of the IR to be studied alongside these. The British IR would have been a revolution even if sustained growth hadn’t occurred.

In contrast, the take-off to sustained growth is specifically and particularly about growth in output per worker. Under what conditions will population growth fail to keep up with output growth caused by technological change? What UGT demonstrates is that something needs to shift in the demographics for sustained growth to occur. Technology, however widely defined, is not enough. It is not until technology changes the trade-off between quantity and quality of children that sustained growth happens.

While UGT focuses on general conditions for the take-off, it is a mistake to think that UGT rules out path dependence or historical contingency. There is nothing in UGT that makes take-off inevitable. Under the right conditions on the demographic or technology functions, an economy will end up stagnating forever. UGT focuses on the take-off because that is what we see in the data, but it need not be the case.

One source of confusion is that UGT papers often use the British experience for examples of the forces at work (I cannot begin to count the number of papers I’ve read that try to calibrate their model to UK data). That, I think, has led to the impression that UGT is meant as a competing explanation for the British IR. It’s not, and the UGT crowd can and should do better in moving beyond the British IR in terms of stylized facts. That would go a long way towards making the distinctions clearer in the literature.

But UGT is not in any sense mutually exclusive with detailed economic history work. If someone wakes up tomorrow and shows that both Mokyr and Allen are wrong about the British IR, that doesn’t mean UGT “wins”. And if someone wakes up tomorrow and shows that some central result of UGT is theoretically incorrect, that doesn’t mean Mokyr or Allen are right. We should all be focused on the true enemy of increased understanding: grading papers.

The Loss of Skill in the Industrial Revolution

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There’s a recent working paper by Alexandra de Pleijt and Jacob Weisdorf that looks at skill composition of the English workforce from 1550 through 1850. They do this by looking at the occupational titles recorded in English parish records over that period, and code each observed worker by the skill associated with their occupation. They use the standardized Dictionary of Occupational Titles to infer the skill level for any given occupation. For example, a wright is a high-skilled manual laborer, a tailor is medium-skilled, while a weaver is a low-skilled manual laborer.

de Pleijt and Weisdorf 2014

The big upshot to their paper is that there was substantial de-skilling over this period, driven mainly by a shift in the composition of manual laborers. In 1550, only about 25% of all manual laborers are unskilled (think ditch-diggers), while 75% are either low- or medium-skilled (weavers or tailors). However, over time there is a distinct growth in the the unskilled as a fraction of manual laborers, reaching 45% by 1850, while the low- and medium-skilled fall to 55% in the same period. You can see in their figure 10 that this shift really starts to take place by 1650, while before the traditional start of the Industrial Revolution.

Looking at more refined measures, de Pleijt and Weisdorf find that the fraction of workers classified as “high-quality workmen” – carpenters, joiners, wrights, turners – rose only from 3.9% to 4.9% of the workforce between 1550 and 1850. These are precisely the kinds of workers that Joel Mokyr claims are the crux of the Industrial Revolution in England. They built, improved, adapted, and micro-innovated all the classic inventions of the IR. While they were only between 4-5% of the workers, and this proportion didn’t expand rapidly, given population growth the absolute numbers of these high-quality workmen went up by a factor of 4 between 1700 and 1850 (from about 200K to 850K).

It’s a really interesting paper, and it’s neat to see how much information you can keep sucking out of these parish records from England. It leaves me with two big questions/ideas. First, does industrialization depend on a concentrated core of skills, rather than a broad distribution of skills? That is, if Mokyr is right about the source of English industrialization, then it’s those extra 650K high-skilled workers that really made all the difference. Industrialization didn’t involve spreading skills all around the (rapidly expanding) population, but in getting together a critical mass of skilled workers. Are we paying too much attention to average human capital levels when we talk about development and growth, and not enough to looking at when/how/if countries achieve that critical mass of skilled workers? Is the overall level of education irrelevant to industrialization?

Second, should we care about de-skilling? In a vacuum, telling someone that the share of unskilled workers in the economy rose from 25 to 40% of all workers would send up red flags. That must be a bad thing, right? Is it? As England added population, much of that new population was unskilled, presumably because there was no longer a demand for certain low- and medium- skilled professions that had been replaced by machines. Could this just mean that the economy was getting more efficient at using the human capital at hand? England didn’t need to waste all that time and effort skilling-up a big mass of workers. They could be used immediately, without much training.

True, real wages didn’t rise between 1550 and 1800 (but from 1800 to 1850 they seem to start taking off, see Clark, 2005). But they also didn’t fall. That is, despite the fact that even before the classic IR the population of England was deskilling, there wasn’t a demonstrable fall in living standards. So doesn’t that imply that England was getting more (output) from less (human capital)? That’s a good thing, right? If England had held the level of human capital constant, then this would have raised real wages per worker. Instead, they chose to lower the amount of human capital while leaving real wages per worker the same. Who’s to say that this is a worse outcome?

If we were talking about innovations that got more output from less energy, then holding output constant while lowering energy consumption would be what everyone hoped to see. Why should human capital be different?