How important is nutrition to economic development? Historically, development was paralleled by growth in population and urbanization. Hence, one way to gain some insight into this question is to understand the role that nutrition played in the historical growth in population and urbanization.
The traditional explanation for the rise in population is that medical advances, such as the understanding of germ theory or the innovation of vaccinations, and improvements in public sanitation greatly decreased infant and child mortality, which, in turn, led to an increase in population. However, in recent years, scholars such as British medical researcher Thomas McKeown and University of Chicago economic historian Robert Fogel have argued that the increase in population was mostly due to an improvement in nutrition rather than the advances in medicine or sanitation.
McKeown argued that the decline in mortality began to occur well before the most important innovations such as antibiotics or vaccinations, which did not become prevalent until the 20th century and, therefore, there is scope for other factors to contribute to the rise in population.
Fogel, who won the 1993 Nobel Prize in economics, argued that since height is positively correlated with nutritional investment during childhood as well as lower mortality rates, then the observation that heights in the US and the UK were increasing is evidence that nutrition was improving during this period.
If Fogel is right, then we have to ask what caused the improvements in nutrition. Certainly, improvements in agricultural technology are part of the story. During this time, a number of productivity-enhancing technologies were developed. Examples include the seed drill, the threshing machine and the Rotherham swing plough.
We have argued in a 2009 Centre for Economic Policy Research, or CEPR, discussion paper, “The Potato’s Contribution to Population and Urbanization: Evidence from an Historical Experiment”, that another main contributor was the discovery of New World food crops—namely, the potato. Potatoes are extremely nutritious and a very “cheap” source of calories. They produced much higher yields per acre relative to pre-existing Old World staple crops.
Historical survey data from England shows that if a family of four were to subsist on only one crop, it would require 66% less land if it were to plant potatoes rather than staples such as barley, wheat or oats. Potatoes are also easy to store and were popular as fodder for livestock through the winter.
Therefore, cultivating potatoes also indirectly improved protein intake. The diffusion of potatoes also had a tremendous impact on nutrition in the Old World because vast land areas in northern Europe, Asia and high altitude areas of Africa were suitable for cultivating potatoes.
Our results suggest that the availability of this high-yielding crop dramatically increased population and urbanization. The introduction of potatoes can explain 22% of the rise in population and 47% of the rise in urbanization during the 18th and 19th centuries.
Edited excerpts, published with permission from VoxEU.org. Nathan Nunn is assistant professor of economics at the University of British Columbia, Canada. Nancy Qian is assistant professor of development economics at Brown University, US. Comment at firstname.lastname@example.org