Beauty: In the gonads of the beholder — and the beheld

AnthropologyHuman Evolutionary Biolog

Fetal Programming and Fetal Psychology

The introduction of the ‘fetal programming hypothesis’, first in epidemiology, subsequently in a broad range of disciplines concerned with developmental biology, has generated new interest in phenotypic plasticity, the mechanisms that govern it, and its place in evolutionary biology. A number of epidemiological studies link small size at birth, assumed to be a consequence of constrained prenatal energy availability, with adverse effects on the risk of chronic diseases later in life. The cluster of chronic diseases associated with the metabolic syndrome and alterations of glucose metabolism are particularly implicated. Recent evidence suggests that epigenetic modification of gene expression affecting the hypothalamic-pituitary-adrenal (HPA) axis may be involved in these effects. In animal studies epigenetic alteration of HPA axis activity and responsiveness is associated with changes in adult behaviour and stress responsiveness. The potential for similar effects to contribute to psychological and psychiatric outcomes in humans has been explored in a number of contexts, including famine exposure, observed covariance with birth weight, and prenatal dexamethasone treatment of fetuses at risk of congenital adrenal hyperplasia. While fetal programming effects have now been widely demonstrated across species and human populations, the adaptive significance of these effects is still a matter of debate.Human Evolutionary Biolog

Life Historical Perspectives on Human Reproductive Aging

A commentary is offered on the chapters that comprise the section on Theoretical Foundations, emphasizing novel contributions of each. Three additional points are then made. First, while the biology of reproductive aging may be common to all human populations, its actual course can be expected to vary between individuals and between populations depending on ecological conditions and developmental histories. Second, increasing fertility (such as that typical of humans compared with hominoid relatives and imputed ancestral species) decreases the opportunity and impact of contributions from ascendant relatives and increases the opportunity and impact of contributions from collateral and descendent relatives in promoting the fitness of a focal individual. Finally, an argument is made that the major change in human life history physiology in the Pleistocene has been the extension of adult lifespan, not any change in ovarian physiology or rate of reproductive senescence, and that extended lifespan created a selection pressure for the emergence of indirect reproductive effort among postreproductive individuals, not the reverse.AnthropologyHuman Evolutionary Biolog

Enhancing the quality of published research on ethnicity and health: is journal guidance feasible and useful?

Researching ethnicity and health presents significant ethical, conceptual and methodological challenges. While the potential contribution of research evidence to tackling ethnic inequalities in health is recognised, there are widespread concerns regarding the ethical and scientific rigour of much of this research and its potential to do more harm than good. The introduction of guidance documents at critical points in the research cycle - including within the peer-review publication process - might be one way to enhance the quality of such research. This article reports the findings from the piloting of a guidance checklist within an international journal. The checklist was positively received by authors and reviewers, the majority of whom reported it to be comprehensible, relevant and potentially useful in improving the quality of published research. However, participation in the pilot was poor, suggesting that the impact of such a checklist would be very limited unless it was perceived to be an aid to authors and reviewers, rather than an additional burden, and was strongly promoted by journal editors

Weight change and ovarian steroid profiles in young women

Objective: To investigate possible short-term effects of voluntary weight loss on ovarian steroid profiles in young women, in light of better established long-term effects in older women. Design: We tested for an association of voluntary weight change over the course of a menstrual cycle with salivary E2 and P profiles in the same menstrual cycle. Setting: Students were recruited in a college residence hall, and they provided daily saliva samples to a researcher living nearby. Patient(s): The 65 women who participated were all college students and ranged in age between 18 and 23 years. Intervention(s): None. Main Outcome Measure(s): Weight was assessed in the first week of the menstrual cycle and first week of the following menstrual cycle. Estradiol and P were measured by radioimmunoassay in daily saliva samples. Result(s): We did not detect a suppressive effect of weight loss on the overall level of either hormone. However, we did find evidence for more distinct follicular and luteal E2 peaks in women who gained weight. Peak luteal P also arrived about 2 days earlier in women who gained weight. Conclusion(s): This finding adds to evidence that short-term response of ovarian function to weight loss in young women is less pronounced than long-term response in older women.AnthropologyHuman Evolutionary Biolog

Diffuse Interstellar Bands in z < 0.6 CaII Absorbers

The diffuse interstellar bands (DIBs) probably arise from complex organic molecules whose strength in local galaxies correlates with neutral hydrogen column density, N(HI), and dust reddening, E(B-V). Since CaII absorbers in quasar (QSO) spectra are posited to have high N(HI) and significant E(B-V), they represent promising sites for the detection of DIBs at cosmological distances. Here we present the results from the first search for DIBs in 9 CaII-selected absorbers at 0.07 < z_abs < 0.55. We detect the 5780Ang DIB in one line of sight at z_abs = 0.1556; this is only the second QSO absorber in which a DIB has been detected. Unlike the majority of local DIB sight-lines, both QSO absorbers with detected DIBs show weak 6284Ang absorption compared with the 5780Ang band. This may be indicative of different physical conditions in intermediate redshift QSO absorbers compared with local galaxies. Assuming that local relations between the 5780Ang DIB strength and N(HI) and E(B-V) apply in QSO absorbers, DIB detections and limits can be used to derive N(HI) and E(B-V). For the one absorber in this study with a detected DIB, we derive E(B-V) = 0.23mag and log[N(HI)] >= 20.9, consistent with previous conclusions that CaII systems have high HI column densities and significant reddening. For the remaining 8 CaII-selected absorbers with 5780Ang DIB non-detections, we derive E(B-V) upper limits of 0.1-0.3mag.Comment: 5 pages, 2 figures. Accepted to MNRAS Letter

Testosterone, Aging, and Seasonality Among Toba Men of Northern Argentina

Originally hunter-gatherers, the Toba of northern Argentina now exhibit a range of subsistence practices. Their environment, diet, and physical activity patterns are considerably seasonal. With the purpose of examining seasonal and age-related changes in testosterone (T) levels, we collected morning and evening saliva samples and anthropometric measures from 153 men ages 12 to 83, in each of three distinct seasons. Data from a subset of n=48 men were used for repeated measures analyses. Mean body mass index (BMI) was 24.1± 3.3 kg/m2 and no statistically significant seasonal differences in body mass were found. Salivary T concentration fell within the range of those found in other non-industrialized populations. No statistically significant associations were found between overall T levels and age (r=-.16, p=.28), height (r=0.04, p=.78), or BMI (r=-0.08, p=.59). Circadian variation was non-significant as well (t(47)=0.99, p=.32). T levels showed a seasonal pattern, peaking during the hot, rainy season (140 vs 180 pmol/L, cold vs hot season, t(46)=3.36, p=.002). Previous demographic and reproductive ecology studies indicated that conceptions and ovarian hormone levels peak during this season as well. Younger men seem to be contributing more to the seasonal difference (age x season interaction effects). We will discuss biosocial effects on T levels, including physical and sexual activity levels across seasons, which appear to support they hypothesis that T regulates energy allocation towards mating effort.AnthropologyHuman Evolutionary Biolog

Energetics, Reproductive Ecology, and Human Evolution

Human reproductive ecology is a relatively new subfield of human evolutionary biology focusing on the responsiveness of the human reproductive system to ecological variables. Many of the advances in human, and more recently primate, reproductive ecology concern the influence of energetics on the allocation of reproductive effort. This paper reviews eleven working hypotheses that have emerged from recent work in reproductive ecology that have potential bearing on the role of energetics in human evolution. Suggestions are made about the inferences that may connect this body of work to our efforts to reconstruct the forces that have shaped human biology over the course of our evolutionary history.AnthropologyHuman Evolutionary Biolog