The authors begin by noting that there is still some disagreement on the overall effect of Japanese rule on the economic welfare of the Taiwanese themselves. While there is little debate that key indicators rose, and productivity and economic output rose, there is still some disagreement on the effect of the growth on the welfare of the Taiwanese themselves, with a few scholars arguing that Japan's extractive policies took most of the gains, and Taiwanese capitalism was stunted. The problem, scholars realize, is that adequate data of income under the Japanese are lacking.
According to Morgan and Liu, studies of human growth have shown that average population height is "primarily attributable to the environment" in which it lives. All other things being equal, taller populations live better. Height itself is a function of net nutrition over time. A well-fed population will enjoy good growth, and even temporary impairment of nutrition can be made up, but long-term lower nutrition will result in permanent falls in height. The authors observe later in the paper that height cycles similar to the business cycle have been detected. I guess I have Nixon to thank for me not being able to play starting forward for the Pistons....
While height and income are correlated, the relationship is not linear. Incremental rises in height decrease as income rises, and in some cases may even diverge. Moreover, height is more closely related to income distribution, they observe. Not only is the gain affected by public health and other factors, but shifts in consumer preferences may also influence it.
Using several different databases, the authors then explore the changes in the average heights of males during the period of Japanese colonialism in Taiwan. There appear to be some correlations with region (central Taiwan people were taller), occupation (professional and skilled were taller), and education (better-educated were taller). After analysis of the data, the authors found that height rises rapidly through the 1910s and 1920s, and then levels off during the 1930s. In fact, that decade is the only period from the 1880s through the 1970s in which growth in height was not regular, according to the authors. The authors conclude:
"The statistical evidence for the flat trajectory of in height during the 1930s-40s is striking confirmation of the adverse impact on the Taiwanese of the shift in colonial policy in the early 1930s, as Japan increasingly militarized and reoriented development in its colonies to support projection of imperial power."These gains were driven by improved public health, economic growth, and economic policy. In Taiwan Japan reduced infant mortality, and eliminated tropical diseases. In a footnote there is an impressive quote from George Mackay, the 19th century missionary, on how malaria laid low large fractions of the population, preventing it from doing meaningful work. At the same time incomes nearly doubled in the 1920s, and the income distribution improved, changes confirmed by both the height data and economic data. In the 1930s economic policy changed and the minor industrialization Taiwan was undergoing may have led to drops in the health of the population, as rural laborers shifted to factory employment, even though most people stayed on the farms where subsidies to rice drove rising incomes. Consumer preferences may have changed, promoting purchases of goods that detracted from health. The economic and historical data are not clear, however.
Overall, their conclusion is that whatever you may say about colonialism, there is no denying that it produced gains in the height, health, and lifespan of the Taiwanese. Japanese colonialism in Taiwan was about more than just laying the foundation for the miracle growth during the KMT period; it was about major improvements in living standards for most Taiwanese.