Saturday, August 21, 2010

Height and Selective Mortality

Empoverished early conditions affect stature through a variety of channels. In general we expect that people who grow up in environments with inadaquate nutrition, poor sanitation and so on to be shorter. Recent evidence from global surveys bears this out. However, a number of papers find that African countries in general deviate from expected heights. This is most  clearly shown in a 2007 PNAS paper by Angus Deaton. Deaton's conclusion is an important one for people using height as an adult indicator of stressed early childhoods:

This paper investigates the environmental determinants of height across 43 developing countries. Unlike in rich countries, where adult height is well predicted by mortality in infancy, there is no consistent relationship across and within countries between adult height on the one hand and childhood mortality or living conditions on the other. In particular, adult African women are taller than is warranted by their low incomes and high childhood mortality, not to mention their mothers' educational level and reported nutrition. High childhood mortality in Africa is associated with taller adults, which suggests that mortality selection dominates scarring, the opposite of what is found in the rest of the world.
 A recent review by Steckel is worth reading in terms of the considerations that should be employed when using height data:

Heights and human welfare: Recent developments and new directions

Author info | Abstract | Publisher info | Download info | Related research | Statistics
Author Info
Steckel, Richard H.
Additional information is available for the following registered author(s):

Since 1995 approximately 325 publications on stature have appeared in the social sciences, which is more than a four-fold increase in the rate of production relative to the period 1977-1994. The expansion occurred in several areas, but especially within economics, indicating that heights are now widely accepted as useful measure of human welfare. Much of this new work extends beyond the traditional bailiwick of anthropometric history, including biological welfare during economic and political crises; anthropometric determinants of wages; the welfare of women relative to men in the contemporary world; the fetal origins hypothesis; and inequality in the developing world. The approach has also expanded within economic history to consider the consequences of empire for colonials; the health of populations lacking traditional measures of social performance; the consequences of smallpox; and very long-term trends in health. Much has also been learned about socioeconomic aspects of inequality, the welfare implications of industrialization, and socioeconomic determinants of stature. The last is a work in progress and one may doubt whether sufficient longitudinal evidence will become available for a complete understanding of the variety and strength of pathways that affect human physical growth.

No comments: