Early life environment, fertility and age of menarche: A test of life history predictions using a longitudinal assessment of adversity perception and economic status

Perceptions of early life environmental adversity can affect the timing of life history transitions and investment in reproductive effort. These effects are well documented in non-human organisms, but have been challenging to test in humans. Here we present evidence of the effects of variables associated with extrinsic mortality and morbidity on reproductive effort in a contemporary American population. Using a longitudinal database that sampled participants (N ≥ 1,579) at four points during adolescence and early adulthood, variables reflective of perceptions of adversity and risk were significantly associated with age of menarche and early adult fertility. While other factors related to energetics and somatic condition could not be assessed, the results of this study support the hypothesis that perceptions of adversity early in life are associated with differences in reproductive effort. How these factors may covary with energetics and somatic condition remains to be assessed

An evolutionary perspective on health psychology: New approaches and applications

Although health psychologists' efforts to understand and promote health are most effective when guided by theory, health psychology has not taken full advantage of theoretical insights provided by evolutionary psychology. Here, we argue that evolutionary perspectives can fruitfully inform strategies for addressing some of the challenges facing health psychologists. Evolutionary psychology's emphasis on modular, functionally specialized psychological systems can inform approaches to understanding the myriad behaviors grouped under the umbrella of “health,” as can theoretical perspectives used by evolutionary anthropologists, biologists, and psychologists (e.g., Life History Theory). We detail some early investigations into evolutionary health psychology, and we provide suggestions for directions for future research

Diurnal variation in salivary cortisol across age classes in Ache Amerindian males of Paraguay

Objectives: Cortisol levels exhibit a diurnal rhythm in healthy men, with peaks in the morning and troughs in the evening. Throughout age, however, this rhythm tends to flatten. This diurnal flattening has been demonstrated in a majority of industrialized populations, though the results have not been unanimous. Regardless, little attention has been paid to non-industrialized, foraging populations such as the Ache Amerindians of Paraguay. As testosterone levels had previously been shown to diminish with age in this population (Bribiescas and Hill, 2010), we hypothesized that cortisol levels would behave similarly, flattening in rhythmicity over age. Methods: We examined morning and evening salivary cortisol samples in Ache Amerindian men in association with age (n=40, age range: 20-64 years). Results: Men in the first age class (50 years, respectively) did not exhibit a significant difference between AM and PM values. Conclusion: Ache Amerindian men exhibit a flattening of the diurnal rhythm across age classes. Our results were able to capture both within- and between-individual variations in cortisol levels, and reflected age-related contrasts in daily cortisol fluctuations. The flattening of the diurnal rhythm with age among the Ache may reflect a common and shared aspect of male senescence across ecological contexts and lifestylesAnthropolog

Testosterone levels are negatively associated with childlessness in males, but positively related to offspring count in fathers

Variation in testosterone (T) is thought to affect the allocation of effort between reproductive and parenting strategies. Here, using a large sample of elderly American men (n = 754) and women (n = 669) we examined the relationship between T and self-reported parenthood, as well as the relationship between T and number of reported children. Results supported previous findings from the literature, showing that fathers had lower T levels than men who report no children. Furthermore, we found that among fathers T levels were positively associated with the number of children a man reports close to the end of his lifespan. Results were maintained when controlling for a number of relevant factors such as time of T sampling, participant age, educational attainment, BMI, marital status and reported number of sex partners. In contrast, T was not associated with either motherhood or the number of children women had, suggesting that, at least in this sample, T does not influence the allocation of effort between reproductive and parenting strategies among women. Findings from this study contribute to the growing body of literature suggesting that, among men, pair bonding and paternal care are associated with lower T levels, while searching and acquiring sex partners is associated with higher T levels.27 Jun 2013: Pollet TV, Cobey KD, van der Meij L (2013) Correction: Testosterone Levels Are Negatively Associated with Childlessness in Males, but Positively Related to Offspring Count in Fathers. PLoS ONE 8(6): 10.1371/annotation/bccccb7e-48a7-4594-b3e6-ce8c9d2489a2

Regional variation in Ascaris lumbricoides and Trichuris trichiura infections by age cohort and sex: effects of market integration among the indigenous Shuar of Amazonian Ecuador

Background: Soil-transmitted helminth (STH) infection peaks during childhood and varies by sex. The impact of market integration (MI) (increasing production for and consumption from a market-based economy) on these infection patterns, however, is unclear. In this study, STH infection is examined by sex and age among indigenous Shuar inhabiting two regions of Amazonian Ecuador: (1) the modestly market-integrated Upano Valley (UV) and (2) the more traditional Cross-Cutucú (CC) region. Methods: Kato-Katz fecal smears were examined for parasite presence and infection intensity. Factorial ANOVAs and post hoc simple effects analyses were performed by sex to compare infection intensity between regions and age categories (infant/child, juvenile/adolescent, adult). Results: Significant age and regional differences in Ascaris lumbricoides and Trichuris trichiura infection were detected. Overall, infants/children and juveniles/adolescents displayed higher parasite loads than adults. CC females exhibited higher A. lumbricoides loads than UV females, while the opposite pattern was observed for T. trichiura infection in males. Conclusions: Regional infection patterns varied by sex and parasite species, perhaps due to MI-linked environmental and lifestyle changes. These results have public health implications for the identification of individuals at risk for infection and contribute to ongoing efforts to track changes and alleviate STH infection in indigenous populations undergoing MI

A Longitudinal Assessment of Associations between Adolescent Environment, Adversity Perception, and Economic Status on Fertility and Age of Menarche

<div><p>Purpose</p><p>Perceptions of environmental adversity and access to economic resources in adolescence can theoretically affect the timing of life history transitions and investment in reproductive effort. Here we present evidence of correlations between variables associated with subjective extrinsic mortality, economic status, and reproductive effort in a nationally representative American population of young adults.</p><p>Methods</p><p>We used a longitudinal database that sampled American participants (N ≥ 1,579) at four points during early adolescence and early adulthood to test whether perceptions of environmental adversity and early economic status were associated with reproductive effort.</p><p>Results</p><p>We found that subjectively high ratings of environmental danger and low access to economic resources in adolescence were significantly associated with an earlier age of menarche in girls and earlier, more robust fertility in young adulthood.</p><p>Conclusion</p><p>While energetics and somatic condition remain as possible sources of variation, the results of this study support the hypothesis that perceptions of adversity early in life and limited access to economic resources are associated with differences in reproductive effort and scheduling. How these factors may covary with energetics and somatic condition merits further investigation.</p></div

Descriptive statistics for the variables of interest.

<p>Descriptive statistics for the variables of interest.</p

Correlates to age at menarche.

<p><b>(A)</b> Kaplan-Meier survival estimation of percent of population who have not reached menarche by perceived safety of adolescent neighborhood. <b>(B)</b> Comparison of mean age at menarche by perceived safety of adolescent neighborhood, t(3,604) = 3.304, p = .0005. For both A & B graphics, N = 425 in unsafe neighborhood, N = 3,181 in safe neighborhood. <b>(C)</b> Comparison of age at menarche by household family income in early life, β = 0.0015, p<0.01, N = 2702.</p