Heart-shaped potato
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Go to work on a potato

I didn’t do modern history at school so my impression of the industrial revolution is largely a mish-mash of pop history and some misremembered Industrial Archaeology courses. What I do recall is that the emphasis in the Industrial Revolution is firmly on the Industrial side. Agriculture existed as a place for people to leave to work in factories. This doesn’t work. To understand the past you need a much more active view of agriculture.

Heart-shaped potato
The industrial world was built on a love of potatoes? Photo by Michael Kooiman

If you take the view that people were employed on farms for a reason, they’d still be needed on the farms when the Industrial Revolution happened. If those people suddenly aren’t there, why doesn’t mass starvation follow? Nunn and Qian argue there was a change in agriculture too, and that was potato farming. The idea isn’t new. The spread of potato farming and it’s influence on feeding people has been argued for by historians. Nunn and Qian’s paper, The Potato’s Contribution to Population and Urbanization, is different because it’s quantitative.

The task they’ve got is difficult, because economies and societies are complex systems. What can you meaningfully measure and compare to other variables? Nunn and Qian have started by measuring the land in Europe suitable for potato farming. They are a lot closer to the tropics in the New World than in Europe, but their habitat is also higher altitude giving a colder environment to grow in. In the Old World, the lower altitude mean that temperate Europe was the prime location for potatoes, and they take into account the difference in the suitability for warmer and colder climates.

They also look at the reasons for slow uptake of potatoes, including the botanical factors which can be easily forgotten today. In the sixteenth and seventeenth centuries it seems that potatoes were as freakish to Europeans as Australian wildlife was later when it was discovered. Potatoes were grown from tubers, not seeds. This was unlike anything seen. It looked unappealing. In fact Nunn and Qian add the note that on the doctrine of signatures popular at the time, the appearance of the potato made it look like it was connected to leprosy. In that situation it’s less surprising that the pioneers to cultivate potatoes regularly were Irish peasants.

Cultivation made a massive change to what was possible. The potato was staggeringly successful in yielding more calories per acre than other crops. This, Nunn and Qian say, is why other New World crops were so much less successful. You can grow maize in Europe, but why would you want to? Sweet potatoes offered little than yams did not already provide and cassava had its own problems with lack of protein and toxins.

Measuring calorific yield is a start, but it’s a blunt tool. Nunn and Qian argue that the importance of the potato can be seen by close examination of the data. In particular they have looked at the heights of French soldiers and examining where they come from. In villages that had suitable land for potato farming there’s an average gain of half an inch in height. They conclude that the potato was responsible for around a quarter of the population increase in the Old World, and made a similar contribution to urbanization.

This last point puzzled me, because I wasn’t clear what urbanization was. The definition eventually appears twenty-three pages into the paper, in a discussion on Population and Urbanization Data:

Urbanization is measured as a country’s total urban population, defined as people living in locations with forty thousand or more
inhabitants, divided by the total population.

From my background that seems an arbitrary figure, but I would guess that it’s a shared arbitrary figure common to economists allowing comparisons between different papers, so this is no big problem.

Thanks to Alan Cann for pointing me at this paper, it looks well-argued. I have to say looks as I couldn’t follow some of the economic arguments well enough to be sure. It makes it a difficult paper to write about too, because there’s a lot of detail necessary to back up the arguments as well as a broad conclusion. Read in isolation there’s room for pedantry, like correlation not being causation, but as Nunn and Qian make clear this is a contribution to a wider debate, and the references are there to place this paper in that debate. Adding the qualitative arguments as well would be both redundant and make the paper at least double in length.

There is a lot of modern relevance to centuries old agriculture. The pop historical approach is that industry superseded agriculture. Likewise in the modern world the decline of industry is celebrated by some people as evidence that new economic sectors are superseding industry. Nunn and Qian show that the opposite is true. Industry was fuelled by advances in agriculture. It seems reasonable to conclude that agricultural innovation and an industrial backbone will still be needed for future economies.

Nunn, N & Qian, N. 2011. ‘The Potato’s Contribution to Population and Urbanization: Evidence from a Historical Experiment’ The Quarterly Journal of Economics, 1–58. doi:10.1093/qje/qjr009

Photo IMGP1090a by Michael Kooiman. Licenced under a Creative Commons BY-SA licence.

Alun Salt

Alun (he/him) is the Producer for Botany One. It's his job to keep the server running. He's not a botanist, but started running into them on a regular basis while working on writing modules for an Interdisciplinary Science course and, later, helping teach mathematics to Biologists. His degrees are in archaeology and ancient history.

1 comment

  • I’m afraid my schooling left me with a blank between the black death and the 20th century, but given most of my commercial work seems to be medieval these days I’ve had a bit of a crash course. The paper sounds interesting but my impression there is already a lot of discussion about the agricultural revolution which was needed for the industrial revolution – we have huge population rises as well as population shifts into the cities ( seems to happen in Italy in the late 2nd century AD as well but I digress) I think we are seeing a shift from very inefficient farming methods ( how much food can ridge and furrow produce for how much labour and land?) as well as major changes in land use ( enclosure acts; cities / towns see to become much more densely populated, so inner city orchards etc disappear ) as well as the application of industrial technology ( if I may put it that way), so the introduction of the potato is one factor of a larger story. My initial feelings are that the arrival of the potato is a bit late – a number of these trends (are already underway in the 13th/ 14th centuries – thinking about when regulations banning thatch in towns (in favour of tile) start coming in which I take as indicative of increasing’urban’ density.
    Now I suppose I’d better loo at the paper!

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