Cutting China (and the past) down to size

Kent Deng and Patrick 0’Brien have joined the ranks of those unconvinced by the Maddison take on historical national accounting, or at least its uncritical acceptance among a broad swathe of scholars of retrospective GDP. And their observations shed welcome light on the widening mismatch between currently fashionable backcast projections and benchmark comparisons of past international output levels.

It’s a broad-ranging paper, covering everything from two millennia of wildly conflicting population estimates (a Deng pet peeve, which he then concludes isn’t particularly relevant here) to the reliability of Ming cultivated acreage returns (which the authors similarly determine can’t be relied upon to resolve the matter).

But the cornerstone of their critique concerns Maddison’s assumed present-day international poverty-line GDP level for the Han era, which informs much of the intervening presently accepted guesswork. Coupled with the World Bank’s controversial (and since partially reversed) 2005 downward revision of China’s (and much of the developing world’s) estimated PPP-adjusted income per capita, their unpicking of the long-run assumptions underlying Maddison’s time series suggests persistent overstatement of China’s GDP. And that raises questions about everyone else's past GDP too.

Indeed, the authors go further:

Sensitivity tests reveal that there is something amiss not simply with the evidence and conjectures for the rates of growth utilized for forward projections from the Han era to 1850 but more seriously with the conceptual foundations of any index expressed in constant 1990 International Dollars utilized as a base line level for the projection of long term trends in GDP per capita.

It’s possible indeed that Deng & O’Brien’s implied downscaling (“implied”, because at this point they sensibly conclude that the numbers game really isn’t worth the candle given the paucity of available data) doesn’t go far enough. The shortcoming here lies in their conversion of Maddison’s Han-dynasty baseline from anachronistic 1990-era dollars to rice-equivalent units, seemingly the first step in their analysis.

I must confess some bafflement at the authors’ argument here. Leaving aside for a moment the crucial conversion error whose correction would strengthen their case hugely, their equating of Maddison’s year 1 CE income to 60% more than the rice-equivalent associated with food security suggests an uncharacteristically conservative conjecture on the late professor’s part. Even very poor people don’t spend all of their scant money on food: there’s clothing and hopefully housing, fuel, tools and utensils to be acquired one way or another, whether by purchase or by making them, either of which means GDP on top of food production. An outlay of 62% of income on the most basic adequate diet seems if anything quite high, still more so when applied to a whole "national” population of poor and rich.

But it isn’t a daily per capita GDP equivalent to a precarious-looking 3,374 kcal of edible rice that’s the problem here, it’s a purported annual income two millennia ago equivalent to something around three tonnes of grain, a level no country (apart from perhaps the odd city-state) attained at current domestic prices before the modern era: even booming eighteenth-century England reached the threshold only once, in 1761, a year of unusually low cereal prices. Here Deng & O’Brien have underplayed their hand spectacularly in converting Maddison’s Geary-Khamis dollar figures to rice-equivalents on the basis of a 1:1.1538 G-K dollar:yuan exchange rate now entirely superseded by intervening ICP revisions and in any case the wrong tool for the purpose.

As noted here previously, a feature of Geary-Khamis modern-dollar GDP results (and a source of my growing annoyance with their incomprehensibly escalating ubiquity in HNA) is that they don’t readily relate to any sectoral or particular product value, thanks to the blanket impact of inflation of output of services and other internationally non-traded items. The consequence is that rebasing the G-K numbers according to any real output quantity just doesn’t work. In my opinion this very non-additivity renders them all but worthless and irrelevant for any meaningful purpose, but on that score I’m in a minority, albeit one that on this latest evidence seems to be growing.

So regardless of any underlying conceptual nonsensicalities, a G-K 1990-price Chinese GDP of $450 two millennia ago shouldn’t necessarily relate to any Chinese rice price of 1990. But while strictly incompatible with the PPP method, the exercise gives a striking illustration of the scale of the problem. The authors' domestic edible rice price (648 yuan per tonne) appears in fact to be the average state procurement price for paddy, and therefore needs raising to take account of farmers' market sales: the result is $135-150 per tonne of paddy, depending on whether we use official or market exchange rates – not far short of the reported global average producer price of $160. As Maddison's prices are international, I use the latter, which also disagrees least with his data.

Estimates for China in the first half of the twentieth century (in which I’ve rather more faith than have Deng & O’Brien) suggest a current-price GDP per capita rather below the value of a tonne of grain. And there’s no reason to believe things had ever been much better given a millennium of improved yields and new crops. On that basis, Han per capita income would be nearer $150 than $450 at 1990 prices - indeed somewhat less, since rice even as paddy tends to command a higher price than most grains.

To put it another way, agriculture (here including forestry and fishing) contributed some $80-90 per head of 1990-price GDP (roughly 550kg in grain-equivalent) in the relatively well-fed mid-1950s, and is most unlikely to have produced appreciably more over any prolonged period in the past. Estimates for the 1930s put its share at 60-65% of current-price GDP, and this time it's unlikely to have previously been much less: recent studies by Broadberry and Shi Zhihong et al indeed put it higher in earlier centuries. But Maddison's Han GDP estimate is at least five times any plausible agricultural value added reckoned at actual 1990 international prices. This might well be a proper consequence of the backcast PPP approach, but would a procedure implying such drastic upsizing and distortion of sector shares really have anything useful to tell us?

Limiting the exercise to Maddison's own calculations up to his death in 2010 indeed understates the scale of the problem. For subsequent work by Bolt & van Zanden finds still higher pre-modern G-K incomes for most regions, though not (yet) for China, which is thus left lagging behind (in itself a wholly plausible finding) even on the basis of a Qing figure that now appears improbably high. Shi & his colleagues go one better by proposing an early Qing per capita GDP of $807 - more than the 2005 ICP revision's implied level for 1990 itself. Broadberry & co go still further with a mindboggling $1,518 (this time exceeding also the perhaps more realistic 2011-derived result) in 1020, only decades into the prosperous Song era and before the impact of early-ripening rice in the south: even supposing China's people each to have munched or worn their way annually through a heroic tonne of grain-equivalent in agricultural output, the latter would barely exceed a tenth of GDP. At a time when we might hope for downward revisions across the board, the message from Groningen, Utrecht and elsewhere is on the contrary one of still further inflation of past incomes.

Deng & O'Brien have done us all a favour with a courageous paper that errs only in pulling its punches when they had the wherewithal to strike a mortal blow at the phantom of an unrealistically bloated economic past which seems to pervade ever more otherwise promising quantitative research. The initial Maddison project gave us an early tentative glimpse into the scale and timing of long-run economic growth, but its increasing tendency to ossification of and extrapolation from questionable and now seemingly superseded data threatens to reduce it to a purely academic exercise ludicrously divorced from historical reality.

Maddison's own shift of base-year from 1980 may itself have exacerbated the problem by widening the divergence between ancient and recent commodity and services prices, though his failings seem small potatoes compared to the reworkings of his heirs. The whole undertaking is in need of more drastic surgery than just more of the same doubtful backcasting of projections from projections. The cure must begin with the price base. Prices of the very recent past can’t be counted on to say much about ancient, medieval or early-modern economies, beyond how big they might have been if the prevailing prices had been those of centuries or millennia later. But they weren’t.

Tax is good for you

Liam Brunt and Cecilia García-Peñalosa offer a provocative take on State capacity, urbanization and the onset of modern economic growth:

We argue that the First Industrial Revolution occurred in England in the middle of the 18th century precisely because it was uniquely urbanized before 1750.

This is something of an oversimplification of the paper’s case: Britons, or more precisely English farmers, produced more because they had to pay out more than foreign growers in rent, tithe and taxes. This forced them to produce more food, thereby supporting larger urban populations whose increased volume and range of economic and social interactions favoured intellectual exchange and innovation. The proposition is attractive in that it draws together the phenomena of agricultural growth, urbanisation and demand-driven and/or technology-led industrialisation. But could agrarian rents really be a driver of urban industry? It’s a lovely thought amid today’s welter of tosh about voting and property rights, but is it a speculation too far?

Brunt & García-Peñalosa seem on solid ground so far as the productivity-urbanisation relationship is concerned. Adam Smith said something similar in 1776:

As subsistence is, in the nature of things, prior to conveniency and luxury, so the industry which procures the former must necessarily be prior to that which ministers to the latter. The cultivation and improvement of the country, therefore, which affords subsistence, must, necessarily, be prior to the increase of the town, which furnishes only the means of conveniency and luxury. It is the surplus produce of the country only, or what is over and above the maintenance of the cultivators, that constitutes the subsistence of the town, which can therefore increase only with the increase of this surplus produce.

As we might expect, higher food output per worker indeed tends to be associated with a larger proportion of townspeople, though an admittedly rough estimate for principal products – albeit one based largely on later data – yields a rather more urban Holland, Belgium & Italy and a more rural Wales, Hungary & Romania than might be suggested by agricultural productivity alone (presumably indicating sizeable food imports among the former group and exports of grain and livestock from the latter).

The authors’ analysis starts by overstating a point that isn’t entirely irrelevant to their analysis, and might usefully have been improved upon:

China, which is regarded by many historians as the most technologically advanced country in the Middle Ages, had much higher urbanization rates than Europe around the year 1000, with about 3 per cent of the population living in cities in the former and virtually zero in the latter. However, over the next 700 years Western Europe experienced a massive increase in urbanization rates, reaching almost 10 per cent by the year 1700, whilst no substantial change took place in China.

This is over-egging the pudding somewhat. The authors’ dismissal of extravagant claims for China’s urbanisation is welcome, and they are right to note that while Europe forged ahead in the following centuries, China struggled to add a single percentage point. But while Europe’s urban population around 1000 was still struggling to recover from its post-Roman low, it certainly wasn’t zero, even in the then relatively peripheral north-west. There are grounds to think that western Europe wasn’t so far behind China, especially if one adopts a lower urban population threshold than the authors’ preferred 10,000 (the cut-off point for de Vries’s city-by-city study): the proportion was lower in north-western Europe, but still not far short of the Continental average. China had more big cities with its sophisticated imperial administration and advanced internal communications, but Europe contained many smaller regional centres, trade emporia and former Roman capitals in varying states of decay or repair. At a more appropriate urban threshold of 2,000 the Europe-China differential would all but disappear.

So perhaps western Europe on the eve of its 11th-century revival wasn’t quite such a backwater in the urbanisation stakes, despite the continent’s relative economic frailty. Just as importantly, by 1300 or even 1200 Europe – however defined - may well have been already ahead, a crucial point lost in comparing only the beginning and end of the 700-year period. This doesn’t invalidate the authors’ case, and may even support it: exactions at the expense of Europe’s cultivators had doubtless increased in the 11th-12th centuries as emerging monarchies and feudal elites jockeyed for advantage. But while overall urbanisation remained low, more precise dating of Europe’s lead underlines the need to look at the medium as well as the long term, and to seek possible explanations of the “Great Divergence” also at times well before the 18th century.

Urbanisation is only one step in the analysis, though a key one in that it is seen as a proximate motor of Europe’s technological revolution. The cornerstone of the authors' argument is the link between agrarian extraction (effectively rent, since this is the main difference between the English and Chinese rates) and the agricultural productivity growth which made large urban populations sustainable. In trying to identify something approaching a “take-off”, however, Brunt & García-Peñalosa seem to have allowed their enthusiasm for English agricultural growth to get the better of them:

Clark finds an increase in output per worker of 44 per cent between 1700-09 and 1770-79. Moreover, Clark documents that output per worker already rose sharply in the 16th and 17th century, increasing fivefold between 1500 and 1650.

A fivefold increase in output per worker in 1500-1650 is of course out of the question, not least given an intervening increase of only around five percentage points in the urbanisation level. Fivefold pre-industrial productivity growth would in any case surely be anathema to Clark’s neo-malthusian heart, necessitating a compensating population increase to soak up the surplus output. In fact Clark finds a productivity drop of about a quarter, not entirely implausible against a background of rapid population growth and the resulting reversal of the land windfall occasioned by the excess mortality of the 14th and 15th centuries. My own estimates suggest a modest rise in labour productivity in the two centuries before 1650, and an increase of a third or so in 1700-70, the latter closer to Brunt (2000) than Clark. For the following century, though, Brunt & García-Peñalosa seem needlessly cautious in their estimates – a rise of a mere fifth when population and trade data suggest an improvement of three-fifths or more. That debate will doubtless run and run, sustained by the high 18th-century output estimates which Clark derives from his series for land rent, wages and capital inputs.

Again, none of this disproves the paper’s basic premise, but it raises once more the issue of timing. There seems to have been nothing exceptional about the level of rural exactions in the latter half of the 18th century when England outstripped its continental rivals in urbanisation (or rather most of them, a significant qualification) and industrialisation: the burdens faced by growers had been in place for at least a couple of centuries, for much of which time provincial urbanisation had been sluggish. Agricultural advance was, like urban growth, a gradual process. But the greatest increases in both agricultural productivity (though not aggregate output) and urbanisation would come in the following century.

The next element – leaving aside the matter of state capacity, not entirely convincingly dealt with (I remain unpersuaded that this correlates with high agrarian rents) – is the scale and impact of compulsory extraction from agriculture:

In table 4 we report the tax burden on agricultural workers in England and China in c.1775, which was almost 100 times greater in England. Since output per worker was around ten times higher in England than in the typical Chinese province, the tax rate was around ten times higher in England than China.

Here again, some of the data seem questionable (“tax” here includes rent and tithe, but that’s clearly indicated). Given that output per English agricultural worker was only perhaps £35 in the 1770s – equivalent to four or five tons of grain – it’s difficult to imagine a Chinese peasant producing a mere tenth as much, still less sharing it among family, landlord, tax-collector and buyers. Chinese productivity was certainly a good deal behind, but a more accurate ratio would seem to be around a third, even lowering Perkins’s generous per capita grain allowance (based as it is on the best years of the 1950s rather than the perhaps more representative 1930s). Nor is the authors’ estimate of 47 pence for China’s land tax per man in agriculture entirely convincing: this might have been the amount going to the Imperial coffers, but other estimates suggest a burden perhaps three times as great after allowing for provincial surcharges, payment in lieu of corvée, outright misappropriation and differences in prices. Again, that doesn’t invalidate the paper’s argument, but it moderates the implied differential, even without considering whether tenancy had already begun to replace peasant ownership on a significant scale, a process whose timing remains unclear.

A more serious shortcoming is the paper’s omission of comparisons between the burdens of English growers and their Continental counterparts. Limiting the exercise to England and China addresses one part of the Great Divergence, but what of the “Little Divergence” within Europe, or perhaps we should say the many little divergences between those countries that surged forward and those that lagged behind? What would estimates for France (where peasant burdens were notorious but urbanisation remained well behind England’s until the latter half of the 20th century) and the highly-urbanised Netherlands or less prosperous lands further east tell us? And what light might, for instance, be shed on the issue by a similar exercise involving British and French territories in North America or the Iberian colonies to the south?

A full comparison of peasant burdens among Europe’s economies alone would be a mammoth undertaking, fraught with still greater difficulty than the relatively clear-cut England-China case. But the example of France suggests that the results may not be so supportive of the Brunt-García hypothesis. Against the authors’ finding of a 23% burden on English farms (possibly on the low side, it must be admitted), that of French peasants has been put at up to a third of output – one of the many grievances that fuelled the Revolution. Yet French agricultural labour productivity remained far below England’s – perhaps £16 of output per person engaged, well over China’s £11 but just half of the English level – and the gap was widening. France was also considerably less urbanised than England, and again falling behind: as late as 1801 under a fifth of the French population lived in towns of 2,000 or more, no greater a proportion than in the England of 1700, and in the meantime England’s urban share (using the same threshold) had topped 35%.

Against the case of France we may contrast that of the Netherlands, where urban population in Holland proper had shot up as early as the 14th century at a time when rural exactions were modest, widespread peasant ownership reflecting easy terms designed to draw cultivators to newly-reclaimed land. By 1514 more than 35% of Holland’s population lived in towns of 2,000-plus, a level not to be matched by England for another three centuries (though of course on a far greater scale), and the province was already a world leader in terms of income. Yet agrarian tenancy only became widespread during the 16th century, with townspeople prominent among the new rural landlord class. City growth continued apace, it’s true, with Amsterdam alone booming from a respectable provincial town of 12,000 in the 1510s to a commercial metropolis of 105,000 in 1622 and 150-200,000 on the eve of the disastrous French invasion half a century later.

But crucially, Holland’s initial urban explosion wasn’t matched by neighbouring provinces with a less unburdened peasantry. Nor was the rapid income growth of 1400-1650 sustained from the third quarter of the 17th century, despite the putative rent stimulus to the industry of an innovative and highly productive farm population. Having quintupled in 1514-1672 to half a million, Holland’s urban population stagnated for the next century and a half. Agrarian productivity remained high, at around £30 per worker, the highest on the Continent owing to a highly developed dairy sector, though by 1770 somewhat behind England. But a comparison of France and Holland – or indeed between 15th- and 18th-century Holland – would yield the very opposite finding to the one suggested by the starker but less like-for-like England-China contrast.

At the end of the day we are left with the familiar chicken-and-egg dilemma. To put it crudely, did London’s population quintuple in 1600-1800 because the bloated land rents of Middlesex’s dwindling rural portion forced the county’s remaining farmers to produce more to feed their urban neighbours? It’s an absurd question, but illustrative of the wider problem of causality. London drew in its supplies from a far wider area, both domestic and international, and while its growth clearly profited from adjacent resources, it in turn impacted on nearby land values: Clark’s early 19th-century rent benchmarks show clear crests around London, Manchester and Birmingham, as might be expected from their leading role in Britain’s commercial and industrial advance.

Brunt and García-Peñalosa’s approach has definite appeal: along with literacy, the rise in European urbanisation well before the classic industrial revolution period remains something of a mystery, if not a cause of the later economic upsurge then at least an expression of forces that would later underlie industrial expansion – whether agricultural growth, diversity and exchange, Allen’s trade-driven high-wage economy or Clark’s “survival of the richest”.

the authors have offered a stimulating avenue for future research, though their approach shares the limitations of all such attempts at monocausal explanation. In fact they could have gone one better by investigating the implications of their tax-and-grow scenario for Allen’s alluring (though itself not fully explained) hypothesis of an exceptionally commercialised economy driven to labour-saving innovation by the cost of its own workers, indeed by its very success. Then we might really be on to something, even if only as a partial answer to the hugely complex question (as Brunt titled his 2000 comparison with France), “Why England?”.

A darker continent

Patrick Manning has some interesting things to say about African population growth in the eighteenth and nineteenth centuries (in press; earlier paper with Scott Nickleach here): whether his conclusions will find widespread acceptance is another matter.

Manning’s latest addition to the growing body of scholarly speculation concerning Africa’s demographic past continues the recent trend toward ever higher estimates of pre-colonial – and here also colonial – population. In place of slow growth interrupted by the devastating impact of slave trading, we now face two-and-a-half centuries of near-stagnation giving way to sluggish recovery.

Where Frankema & Jerven proposed something just under a doubling of the continental total in the century to 1950 – itself a pessimistic growth assessment compared to the earlier guesstimates of McEvedy & Jones and (to a lesser extent) Caldwell – Manning offers a picture of overall decline in the century to 1880 followed by an increase of little over half over the next six decades.

The picture isn’t one of unrelieved gloom, though it comes perilously close: the northern and southern ends of the continent get to grow throughout the nineteenth century (though until 1920 at a pitifully slow rate), while the Guinea coast – the first region to feel the impact of European slave shipments – more-or-less holds its own after the post-1792 decline in removals to the New World.

All present-day estimates of Africa’s mid-twentieth century population seem to agree broadly that the continent contained around 280 million people in 1960 and 220m or so in 1950. There the agreement ends. For 1920, Manning’s estimate of 159m compares with the 147m of Frankema & Jerven, Caldwell’s 142m, and fewer than 135m implied by MacEvedy & Jones. Further back in time, the gap widens: in 1900, 145m (Manning), 137m (Frankema), 129m (Caldwell), 110m (McEvedy); for 1880, 142m, 128m, 120m and under 100m respectively. Manning’s total for 1800 is fully twice McEvedy’s, and 50% greater than the level indicated by Caldwell.

The sources of these large discrepancies are inevitably complex, but for the pre-colonial era they boil down chiefly to the degree to which slave removals and related deaths were offset by demographic recovery, ongoing growth through continued expansion of cultivation, and later the spread of new crops and (toward the end of the period) the beginnings of economic development. For the colonial period, the principal issue is the extent to which early census returns underreported total numbers.

Taking the latter period first (since all the estimates are essentially back-projections from the more reliable data for the 1950s and subsequent decades) there is little disagreement that colonial censuses – many of them barely worthy of the name – generally understated African populations. Contemporary estimates around 1950 indicated a continental total of only around 200 million, roughly a tenth below the true level. Nigeria’s population was widely believed to be only around 25m before the 1952-53 census returned a population of 30m, itself an undercount.

Manning is thus right to raise many of the official colonial population returns. But his procedure goes far beyond mere adjustment of deficient counts and government estimates: what he has done is effectively to discard all the pre-1950 data on the basis of a glib rejection of a few patently flawed guesstimates from the 1930s. This overlooks the wealth of intervening scholarly and indeed bureaucratic revision. European colonial officials were themselves aware by the 1930s of the shortcomings of their raw data, limited as they were by meagre administrative resources and legitimate native distrust of head-counts: the author of Nigeria’s 1931 census report for instance inflated the crude return by a tenth to compensate for under-enumeration and evasion. (Nor were earlier errors in population estimation all in the same direction, unless one is to accept figures of up to 4½m for Uganda in the 1900s.)

For the thus abandoned contemporary figures Manning substitutes assumed “default growth rates” which are themselves highly questionable. For these he draws on trends from the more complete census data for British-ruled India, which he then adopts as maxima for Africa given the continent’s disturbed condition prior to 1920. But this overlooks the very different character of the two regions: India was a long-settled society already boasting extensive dense occupation and highly developed state structures long before the Atlantic slave trade: Africa, by contrast was still in the throes of internal agricultural colonisation, as Caldwell concluded in his 1985 General history chapter (favourably cited by Manning), basing his projections on the assumption that:

the neolithic revolution has been slowly moving through sub-Saharan Africa for three thousand years bringing with it more intensive land use and denser settlement.

Furthermore Caldwell considered the resulting population growth to be accelerating in the nineteenth century through expansion into the forest belt and the spread of new crops (though the latter process was to be more marked during the colonial period). To these developments one might add the ongoing movement of Nguni and other Bantu-speaking peoples into today’s South Africa, nineteenth-century growth in Egypt and the beginnings of European settlement and agricultural transformation. Such an evolution has important implications for long-run estimates, because African population must in the past have been a good deal less than at the start of the colonial era, even allowing for intervening losses to slaving.

Manning’s default rates are not themselves obviously outlandish, the lower bound of his 0.2-0.3% pre-1920 annual range corresponding as it does to the increment needed to raise McEvedy’s “optimistic” 16½m Africans of AD1 to the billion of 2010: indeed given annual growth well in excess of 2% since the 1950s, rates must have been a good deal lower even than this for most of Africa’s past. But to assume such sluggish growth into the modern era reckons without the falling continental population share of the (until 1800) slower-growing north and the geographically ever more constrained hunting & gathering peoples to the south. It may be, of course, that sub-Saharan cultivators’ rate of increase fell markedly following their initial expansion through the southern half of the continent, but this does not appear to have been addressed, nor is there an especially strong case for it given that the global erosion of non-farming populations is likely to have been replicated on a smaller scale even in and around already settled areas.

While growth rates before the twentieth century remain a matter of conjecture, there is far less basis for the severity of Manning’s wholesale downward revision of those for the colonial period. While census-taking was at best patchy and in some areas subject to deterioration, the data for 1910-50 offer a consistent enough picture of quickening growth. That annual growth in the 1950s in most territories comfortably exceeded 2% a year itself suggests that there is nothing intrinsically implausible in rates of 1% or more in the century’s early decades or even of 2% in some areas from the 1930s. Manning’s default rates may be reasonable for the centuries to 1800, but appear at odds with the mounting demographic evidence as we move into the census period, conflicting even with the Indian evidence on which they are supposedly based.

The impact of Manning’s gloomy assumptions can be seen most clearly in the case of Egypt and South Africa, generally considered the continent’s fastest-growing nineteenth-century territories. Where French observers reckoned 2½m Egyptians following Bonaparte’s arrival in 1798 – since raised by twentieth-century scholarship to some 3-5m – Manning estimates 10½m, more than were counted in the census of 1897, usually considered the first reasonably accurate enumeration. For South Africa, his procedure gives 6.3m inhabitants in 1800 against only 5.2m counted in 1904 (the latter doubtless an underestimate, but coming after a century of colonisation both black and white): though probably an understatement like many of his numbers, McEvedy’s figure of a mere 1½m for the earlier year looks far more plausible given that much of the interior remained to be settled, particularly its western half.

There is a further problem with Manning’s projections: recall that these are his “default” rates, extended to the entire period to 1920 on the grounds of the continent’s experience of slave shipments and conquest by European powers. But what he then does is to apply a range of “situational modifications” representing (among others) these same factors, thereby effectively double-counting the losses and disorders which underlie his pessimistic global model. It is the compounding of these various elements which produces the pre-1890 population standstill, where a more plausible underlying growth rate subject to similar modifications would have shown a century of modest but quickening growth, preceded it is true by net losses in at least parts of the continent in the latter decades of the eighteenth century.

In sum, Manning’s estimates are an interesting but seriously flawed contribution to an area of historical demography in need of more work, on colonial demography and on the impact of slave removals & raiding on African populations. By selecting a set of growth rates and countervailing adjustment factors which effectively preclude dynamic development anywhere until well into the last century, he has constructed a model of built-in stagnation which inadvertently minimises Africans’ regenerative capacities and all but ignores widely divergent trends within the continent. There may well be grounds for raising all estimates of past African population, but approaches which offer so little scope for directly observed data and local variation are unlikely to offer a lasting way forward.