The ubiquity and consequences of childhood growth stunting (<-2 SD in height-for-age Z score, HAZ) in rural areas of low-income nations has galvanized research into the reversibility of stunting, but the shortage of panel data has hindered progress. Using panel data from a native Amazonian society of foragers-farmers in Bolivia (Tsimane'), we estimate rates of catch-up growth for stunted children. One hundred forty-six girls and 158 boys 2 < or = age < or = 7 were measured annually during 2002-2006. Annual Delta height in cm and in HAZ were regressed separately against baseline stunting and control variables related to attributes of the child, mother, household, and village. Children stunted at baseline had catch-up growth rates 0.11 SD/year higher than their nonstunted age and sex peers, with a higher rate among children farther from towns. The rate of catch up did not differ by the child's sex. A 10% rise in household income and an additional younger sibling lowered by 0.16 SD/year and 0.53 SD/year the rate of growth. Results were weaker when measuring Delta height in cm rather than in HAZ. Possible reasons for catch-up growth include (a) omitted variable bias, (b) parental reallocation of resources to redress growth faltering, particularly if parents perceive the benefits of redressing growth faltering for child school achievement, and (c) developmental plasticity during this period when growth rates are most rapid and linear growth trajectories have not yet canalized.
Article Archive: Body Height
Immune function is a central component of maintenance effort, and it provides critical protection against the potentially life threatening effects of pathogens. However, immune defenses are energetically expensive, and the resources they consume are not available to support other activities related to growth and/or reproduction. In our study we use a life history theory framework to investigate tradeoffs between maintenance effort and growth among children in a remote area of Amazonian Bolivia. Baseline concentrations of C-reactive protein (CRP) were measured in 309 2- to 10-year olds as an indicator of immune activation, and height was measured at baseline and three months later. Elevated CRP at baseline predicts smaller gains in height over the subsequent three months, with the costs to growth particularly high for 2- to 4-year olds and for those with low energy reserves (in the