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. ORCID 0000-0002-1261-4283

When he's not the web developer for AoB Blog, Alun Salt researches something that could be mistaken for the archaeology of science. His current research is about whether there's such a thing as scientific heritage and if there is how would you recognise it?

1 Response

  1. Phil says:

    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!