Brief Comments on Chinese Life Expectancy Under Mao Zedong
Communists, and tankies in particular, love to repeat the claim that China’s life expectancy l drastically improved under Mao. Below is an example that I found on Twitter.
Occasionally they’ll also reference a paper by Kimberly Singer Babiarz et al.1 The paper claims that “China's growth in life expectancy at birth from 35–40 years in 1949 to 65.5 years in 1980 is among the most rapid sustained increases in documented global history.” But I have a big problem with this. My contention can be summarized in the form of:
Selection bias can’t simply be ignored in studies like this. China experienced mass mortality during the Great Famine and the Cultural Revolution. Up to 45 million people starved to death.2 Now, it stands to reason that the first people to starve were among the poorest, sickest, oldest, dumbest, etc. These are the people who would already have lower life expectancies. So once a huge chunk of the population with lower life expectancies is gone, the average life expectancy would increase. It could even increase if those with higher-than-average life expectancies see a decrease in their lifespans.
To demonstrate this I’d like to point to a paper from The Journal of Development Economics.3 The authors start by discussing the importance of height:
Height is closely related to nutritional intake during childhood. Height is therefore increasingly used as an indirect measure of the material conditions that prevailed during childhood in developing country and historical settings, where direct measures of economic conditions are unavailable or unreliable.
Then they make a similar observation as myself:
When childhood mortality rates are high and if taller children are more likely to survive, bias due to height-related selection can be an added complications for these studies.
Famine will generally cause stunting. But, as the authors say,
If selection outweighs stunting, famines create taller populations, which may be mistakenly interpreted as evidence of an improvement in economic conditions.
The goal of the paper is to measure and control for said selection effects. Looking at the raw data, it appears as though height increased after the Great Famine. However, after controlling for selection effects, the authors found:
…that rural famine survivors who were exposed to the famine in the first 5 years of life are stunted between 1 and 2 cm.
There’s no reason to think that life expectancy is much different. Researchers have observed this happening many times with life expectancy. Most notably in studies of the 1974-1975 Bangladesh famine,4 and the 1866-1869 Finnish famine.5
I was able to find one study published in 2010 in the journal Social Science & Medicine that looks at China specifically.6 The authors also have an almost identical observation as myself:
Selection effects… …refer to the possibility that famine survivors (the surviving part of the famine cohort) tend to be unusually well endowed with some genetic or congenital traits that may reduce mortality risk later in life.
Their findings showed that the famine survivors (famine cohort) were highly selective and well-endowed:
The fact that the famine cohort had a higher mortality than the non-famine cohort for over 11 years until the mortality crossover occurred, combined with the evidence for selection effects as revealed by the positive correlations between frailty in infancy and frailty in childhood, provides so far the best evidence for the presence of both debilitation and selection effects of the 1959-1961 Chinese Leap Forward Famine.
I would love to see someone recreate the life expectancy graph using this new information, but I’m not sure that’ll ever happen. But these papers do show that we should be highly skeptical of data like this. I’m just summarizing and quoting the most important parts of these papers, feel free to go check them out on your own. They’ll all be listed below.
Babiarz, K. S., Eggleston, K., Miller, G., & Zhang, Q. (2014, December 13). An exploration of China’s mortality decline under Mao: A provincial analysis, 1950–80. Population Studies, 69(1), 39–56.
Meng, X., Qian, N., & Yared, P. (2015, April 20). The Institutional Causes of China’s Great Famine, 1959–1961. The Review of Economic Studies, 82(4), 1568–1611.
Gørgens, T., Meng, X., & Vaithianathan, R. (2012, January). Stunting and selection effects of famine: A case study of the Great Chinese Famine. Journal of Development Economics, 97(1), 99–111.
Razzaque, A., Alam, N., Wai, L., & Foster, A. (1990, March). Sustained Effects of the 1974–5 Famine on Infant and Child Mortality in a Rural Area of Bangladesh. Population Studies, 44(1), 145–154.
Kannisto, V., Christensen, K., & Vaupel, J. W. (1997, June 1). No Increased Mortality in Later Life for Cohorts Born during Famine. American Journal of Epidemiology, 145(11), 987–994.
Song, S. (2010, August). Mortality consequences of the 1959–1961 Great Leap Forward famine in China: Debilitation, selection, and mortality crossovers. Social Science & Medicine, 71(3), 551–558.