Economists such as Gregory Clark and Brad DeLong like to tell people that between the dawn of time and 1800 or 1900 there was no growth in GDP per capita and very slow population growth. As an ancient historian this leaves me scratching my head. I decided to write this post after reading the 1998 version of DeLong’s ideas but similar ones appear to be common.
There is quite a bit of historical evidence against DeLong’s specific assumptions, from “people in the past were all really short” (see J. Geoffrey Kron, ‘Anthropometry, Physical Anthropology, and the Reconstruction of Ancient Health, Nutrition, and Living Standards’), to “women in the past had no control over their fertility” (see Janice Liedl or chapter 7 of Barbara Bush, Slave Women in Caribbean Society, 1650-1838) to “conditions in 18th century Europe existed everywhere from time immemorial” (I hope that I don’t need to explain the problems with this one). DeLong writes that he has changed his mind on some things, and I hope that he means that he is familiar with some of this evidence. Yet my biggest surprise is that economists consider this a worthwhile project in the first place.
First, in the ancient world only a tiny fraction of all goods and services were exchanged for money. Economists such as Diane Coyle routinely warn that GDP is a flawed metric in industrial economies because it does not account for parts of the economy which are not monetarized, and sometimes fret about the data-collecting problems which saw Nigeria’s GDP rise 89% in a year after a change in methodology, so I don’t understand how they can use this metric for preindustrial ones. (A few historians such as Walter Scheidel do attempt to estimate average incomes in terms of silver or grain in well-documented societies such as Augustan Italy or late antique Egypt, but they usually acknowledge the limits).
Second, the evidence is not sufficient to construct a history of world population before 1900. There is simply too little census data, and archaeological evidence for population is always ambiguous. Serious estimates of the population of the Roman empire under Augustus based on surviving census figures differ by a factor of three (Walter Scheidel and Geoffrey Kron are two prominent participants in this debate), while estimates of the population of the New World in 1492 based on archaeological remains and estimates by early travellers and colonists differ by a factor of twenty. Estimates of world population history such as the book by McEvedy and Jones tend to assume that population should increase exponentially, and chose numbers accordingly, so they cannot be taken as evidence that the population did in fact increase according to a smooth exponential function. That would be a circular argument. (This problem also affects estimates of ancient incomes and income distribution, since ancient historians tend to adjust their models in keeping with what economists tell them is reasonable, while economists appeal to ancient historians’ estimates to support the economists’ generalizations about ancient societies).
Third, even on purely material grounds, I am bewildered to see conditions in the Paleolithic equated with those in urbanized, literate, agrarian societies. The average person in 10,000 BCE probably lived with a few dozen close relatives, had a literal handful of possessions of stone and organic materials made by generalists from resources within a few dozen miles; his counterpart in Italy under Augustus lived with a few thousand people in a sturdy brick building and had several boxes’ worth of possessions made by specialists from materials drawn from hundreds of miles away. He might eat worse than the forager and be sick more often, but that only strengthens the impression that material conditions in those two cultures were profoundly different. It is not hard to imagine people preferring one way of life over the other, and I suspect that a bit of work would turn up examples in recent times of people who grew up in one kind of society but found the other more attractive. If estimates of GDP cannot capture this difference, so much the worse for them.
Lastly, focusing on the “global GDP” at dates thousands of years apart can obscure that the road between those two was rather bumpy. Ancient economic history was not marked by endless sameness but by an alternation of good years, famines, growing towns, and wars. Somebody born at the beginning of a period of prosperity could expect a very different life than someone born in a period of decline, and wars or revolutions or the founding of a town could have very serious consequences for good or bad. In the long run, everyone dies, but somehow we find what happens in between worth talking about.
In short, world GDP per capita is the wrong metric for the ancient world, we don’t have data to calculate it anyways, and stressing the slow long-term change on the scale of continents rather than the visible change on the scale of single countries and human lifetimes is incomplete. Economic historians are just as much the slave of economists as Keynes’ “practical man” was, but I wish that more economists would show that they take ancient evidence seriously. While I appreciate economists’ desire for generalization and abstraction, generalizations ought to fit the facts.
Further Reading: David Graeber’s Debt seem to have failed to make more economists take the world before 1500 seriously, although it has inspired them to educate the public about the history of Apple Corporation and the structure of the Federal Reserve. Jac J. Janssen, Commodity Prices From the Ramessid Period (E.J. Brill: Leiden, Netherlands, 1975) is an entertaining description of economic life in one ancient society; in my view anyone who wants to understand economic life before the eighteenth century should have conditions in several specific societies firmly in mind before they read their first grand theory or look at estimates of population and income. I discuss these issues at greater length on pp. 60-72 of my master’s thesis. I wrote this sometime in 2014 but decided to post it after reading another philosophical blog post by Brad DeLong (link). For other examples of ideas similar to DeLong’s see eg. William Bernstein‘s The Birth of Plenty or Gregory Clark’s Fairwell to Alms (published by Princeton University Press!).
Edit 2016-01-01: DeLong now cites Roger Fouquet and Stephen Broadberry, “Seven Centuries of European Economic Growth and Decline,” Journal of Economic Perspectives 29:4 (Fall 2014), pp. 227-44 doi=10.1257/jep.29.4.227 as showing that GDP per capita was changing noticeably in most European countries in most years between 1300 and 1800. While I am still not convinced that GDP is the right metric, I think this is a step in the right direction.
Edit 2016-01-29: See now François de Callataÿ (ed.), Quantifying the Greco-Roman Economy and Beyond. Pragmateiai, 27. Bari: Edipuglia, 2014. Pp. 260. ISBN 9788872287446. €60.00. (non vidi sed legi recensionem apud http://bmcr.brynmawr.edu/2016/2016-01-24.html)
Edit 2016-03-09: A BMCR by Kostas Vlassopoulos of the University of Crete accuses a recent book by Josiah Ober of using ideas drawn from American pop economics to tell stories about the Athenian economy without making sure that they fit the sources, particularly the sources for parts of the ancient world other than Athens. If his assessment is accurate, I still think that professional economists are much more likely to make these mistakes than professional historians.
Edit 2016-05-11: DeLong is now preparing to publish an essay which appeals to “the skeletal evidence that finds adult humans around the year 1 little more than five feet tall.” He cites an article from 1995 “Stature and the Standard of Living” by one Richard H. Stecke (link). After a quick skim, I don’t see any precise claims about heights anywhere in the world before the 18th century in that paper, and that paper is certainly overwhelmingly focused on the past 300 years and emphasizes that average heights in any given year vary from place to place.
Edit 2010-01-02: Cosma Shalizi of http://bactra.org/ reports that Oskar Morgenstern, On the Accuracy of Economic Observations (1950) argued that many of the economic statistics published in his day were at least 5-10% in error