Evo-devo of human adolescence: beyond disease models of early puberty

Despite substantial heritability in pubertal development, much variation remains to be explained, leaving room for the influence of environmental factors to adjust its phenotypic trajectory in the service of fitness goals. Utilizing evolutionary development biology (evo-devo), we examine adolescence as an evolutionary life-history stage in its developmental context. We show that the transition from the preceding stage of juvenility entails adaptive plasticity in response to energy resources, other environmental cues, social needs of adolescence and maturation toward youth and adulthood. Using the evolutionary theory of socialization, we show that familial psychosocial stress fosters a fast life history and reproductive strategy rather than early maturation being just a risk factor for aggression and delinquency. Here we explore implications of an evolutionary-developmental-endocrinological-anthropological framework for theory building, while illuminating new directions for research

Fit to WHO weight standard of European infants over time

OBJECTIVES: The 2006 WHO growth charts were created to provide an international standard for optimal growth, based on healthy, breastfed populations, but it has been suggested that Northern European children fit them poorly. This study uses infant weight data spanning 50 years to determine how well-nourished preschool children from different eras fit the WHO standard, and discuss the implications of deviations. DESIGN: Four longitudinal datasets from the UK and one from Finland were used comprising over 8000 children born between1959 and 2003. Weights from birth to 2 years were converted to age-sex-adjusted Z scores using the WHO standard and summarised using Generalized Additive Models for Location, Scale and Shape. RESULTS: Weights showed a variable fit to the WHO standard. Mean weights for all cohorts were above the WHO median at birth, but dipped by up to 0.5 SD to a nadir at 8 weeks before rising again. Birth weights increased in successive cohorts and the initial dip became slightly shallower. By age 1 year, cohorts were up to 0.75 SD above the WHO median, but there was no consistent pattern by era. CONCLUSIONS: The WHO standard shows an acceptable, but variable fit for Northern European infants. While birth weights increased over time, there was, unexpectedly, no consistent variation by cohort beyond this initial period. Discrepancies in weight from the standard may reflect differences in measurement protocol and trends in infant feeding practice

Tradable Pollution Permits and the Regulatory Game

This paper analyzes polluters\u27 incentives to move from a traditional command and control (CAC) environmental regulatory regime to a tradable permits (TPP) regime. Existing work in environmental economics does not model how firms contest and bargain over actual regulatory implementation in CAC regimes, and therefore fail to compare TPP regimes with any CAC regime that is actually observed. This paper models CAC environmental regulation as a bargaining game over pollution entitlements. Using a reduced form model of the regulatory contest, it shows that CAC regulatory bargaining likely generates a regulatory status quo under which firms with the highest compliance costs bargain for the smallest pollution reductions, or even no reduction at all. As for a tradable permits regime, it is shown that all firms are better off under such a regime than they would be under an idealized CAC regime that set and enforced a uniform pollution standard, but permit sellers (low compliance cost firms) may actually be better off under a TPP regime with relaxed aggregate pollution levels. Most importantly, because high cost firms (or facilities) are the most weakly regulated in the equilibrium under negotiated or bargained CAC regimes, they may be net losers in a proposed move to a TPP regime. When equilibrium costs under a TPP regime are compared with equilibrium costs under a status quo CAC regime, several otherwise paradoxical aspects of firm attitudes toward TPP type reforms can be explained. In particular, the otherwise paradoxical pattern of allowances awarded under Phase II of the 1990 Clean Air Act\u27s acid rain program, a pattern tending to favor (in Phase II) cleaner, newer generating units, is explained by the fact that under the status quo regime, a kind of bargained CAC, it was the newer cleaner units that were regulated, and which therefore had higher marginal control costs than did the largely unregulated older, plants. As a normative matter, the analysis here implies that the proper baseline for evaluating TPP regimes such as those contained in the Bush Administration\u27s recent Clear Skies initiative is not idealized, but nonexistent CAC regulatory outcomes, but rather the outcomes that have resulted from the bargaining game set up by CAC laws and regulations

Use of nicotine replacement therapy during pregnancy and stillbirth:a cohort study

Udgivelsesdato: 2008-OctOBJECTIVE: The objective of this study was to examine whether the use of nicotine replacement therapy (NRT) during pregnancy increases the risk of stillbirth. DESIGN: Cohort study with prospective data. SETTING: Denmark 1996-2002. POPULATION: A total of 87,032 singleton pregnancies enrolled in the Danish National Birth Cohort for which information on NRT use as well as smoking was available. METHODS: Outcome of pregnancy was identified by register linkage, with <1% loss to follow up. We conducted Cox regression analyses to estimate the hazard ratio (HR) and 95% CI of stillbirth according to the use of NRT, type of NRT use and a combination of NRT use and smoking. MAIN OUTCOME MEASURES: Stillbirth, defined as delivery of a dead fetus after 20 completed weeks of gestation. RESULTS: A total of 495 pregnancies (5.7 in 1000 births) ended in stillbirth, 8 of which were among NRT users (4.2 in 1000 births). After adjustment for confounders, women who used NRT during pregnancy had a HR of 0.57 (95% CI 0.28-1.16) for stillbirth compared with those who did not use NRT. Smoking during pregnancy was associated with an increased risk of stillbirth (HR 1.46, 95% CI 1.17-1.82), while women who both smoked and used NRT had a HR of 0.83 (95% CI 0.34-2.00) compared with nonsmoking women who did not use NRT. CONCLUSION: Our study does not indicate that use of NRT during pregnancy increases the risk of stillbirth