This study examines sex differences in vulnerability among children experiencing rapid culture change that may reflect distinct microecologies driven by differential parental investment and/or sex-specific life history strategies. Apparent female growth canalization may be a life history strategy favoring growth over maintenance but also may reflect sex-differentiated selection for resilience based on unequal treatment during early life.
Stature, weight, and serum measures of C-reactive protein (CRP, an inflammation marker) and Epstein-Barr Virus antibodies (EBV, a humoral immune response marker) were collected longitudinally among children/adolescents ages 5–20 years (N = 65), 5–9 years after sustained contact in a fringe highland hunter-horticulturalist group from the Schrader Range in Papua New Guinea exhibiting male preference and sex-biased survival. It was hypothesized that girls would exhibit canalization, with better nutritional status than boys; lower maintenance investment would yield lower female immune activation; and because of differential survivorship, females would appear increasingly canalized as early conditions for girls worsened relative to boys.
Girls had greater arm circumference z-scores than boys, less frequent stunting, and lower CRP despite high pathogen load. Average nutritional status for girls improved over time as the sex ratio became increasingly male biased and the condition of female infants reportedly worsened.
Both canalization and survivorship effects were found. Although a life history perspective on female canalization can help explain developmental outcomes in populations undergoing rapid culture change amid adversity, possible sex differences in the strength of survivorship effects that select for resiliency should not be ignored. Am. J. Hum. Biol. 22:657–666, 2010. © 2010 Wiley-Liss, Inc.