Children's Growth in an Adaptive Framework: Explaining the Growth Patterns of American Slaves and Other Historical Populations
This paper presents a new adaptive framework for understanding children's growth in the past. Drawing upon the recent work of Gluckman and Hanson (2006) and their co-authors on adaptive responses in relation to growth, I present three prenatal and three postnatal adaptive mechanisms that affect the growth patterns of children. The most novel adaptive response to the historical literature is the prenatal predictive adaptive response where the foetus develops assuming that the postnatal environment will closely match prenatal conditions. Thus, the metalbolism and growth trajectory of a child is programmed during the prenatal period: children experiencing good conditions in utero would have a higher metabolism and growth trajectory than their counterparts facing poor conditions. Having discussed the framework and other responses in detail, I then use it to reinterpret the growth pattern of American slaves (Steckel, 1979, 1986). I argue that the mismatch between relatively good conditions in utero and absolutely appalling conditions in infancy and early childhood led slave children to become incredibly stunted by age three or four. However, after this age, slave children experienced rapid catch-up growth, first because their immune systems had become more developed and had adapted to the poor disease environment and later because their diet improved tremendously and hookworm exposure was reduced when they entered the labour force around age ten. Thus, American slave children were able to experience rapid catch-up growth because they were prenatally programmed for a higher metabolism and growth trajectory. The paper concludes by setting out some stylized facts about children's growth in the past and pointing toward areas of future research.