Why did children grow so well at hard times? The ultimate importance of pathogen control during puberty

Abstract

Background and objectives: Secular increase in human height and performance occurred in Europe throughout the 20th century despite the temporally worsening access to nutrients during and after World War II. This pattern is paradoxical under the assumption of the major impact of pre- and postnatal growth conditions for determination of adult size and human capital.Methodology: We examined the anthropometric parameters of Estonian girls born between 1938 and 1953, and measured around the age of 17 (n = 1475). This period involved two opposite trends in the economic and epidemiological situation: increasing birth-time economic hardships during the war and particularly in the post-war period, and decreasing infant mortality (a proxy of disease burden) after 1947.Results: Height of girls was negatively affected by the number of siblings and positively by parental socioeconomic position, but these effects were weaker than the secular trend. Leg length (an indicator of pre-pubertal growth conditions) was independent of age and birth date while all other traits, including measures of performance (cranial volume, lung capacity and handgrip strength) showed acceleration. The best predictor of size at age 17 was, in most cases, infant mortality in the year when the girls were aged 11.Conclusions and implications: Reduction of disease burden during pubertal growth can override effects of resource shortage at birth. Our results also support the idea that increasing efficiency of pathogen control can contribute to the secular increase in cognitive abilities, i.e. the Flynn effect, and that epidemiological transition is the main driver of secular increase in human capital.

Father's death does not affect growth and maturation but hinders reproduction: evidence from adolescent girls in post-war Estonia

“…Unfortunately, we lacked data on menarcheal age. We used three measures of growth that appeared most sensitive to different biosocial factors at different ages (legs grow faster than trunk before puberty; see [14]). …”

“…All models were adjusted for relevant developmental and biosocial covariates [14,18]; only significant predictors were maintained. Sample sizes differed between the models because we had an incomplete dataset for some variables.…”

“…The dataset includes girls born between 1938 and 1953 and measured around the age of 17 [14]. Of 1678 girls, 12% (194) reported that their fathers were dead by the time of the study.…”

Parents of early‐maturing girls die younger

“…Data on menarcheal age (see Tables 1 and 2 and Supporting Information Data on the rate of breast development were obtained from the anthropometric study performed by Juhan Aul between 1956 and 1969 (henceforth, Aul's database). The historical background of this sample is described by Hõrak and Valge (2015a). The data set involves 9,331 7-year-old to 24-year-old (mean = 14.…”

Adolescent Cranial Volume as a Sensitive Marker of Parental Investment: The Role of Non-material Resources?

“…Physiological trade-offs can be defined as alteration in allocation of resources between different traits or functions in response to externally or internally induced changes. An example of a physiological trade-off is growth stunting in response to infections that require allocating somatic investments into immune responses at the expense of growth ( McDade, 2003 ; Hõrak and Valge, 2015 ) or sacrificing the growth of some organs or tissues (such as viscera) to protect other organs whose function would be more detrimentally influenced by impaired growth (e.g., brain) in response to intra-uterine nutrient limitation (“thrifty phenotype,” Hales and Barker, 1992 ; Wells, 2013 ). Microevolutionary trade-offs reflect within-population (or higher-order) genetic diversity in continua of life-history and physiological strategies (see Hõrak and Cohen, 2010 ).…”