A variant in LIN28B is associated with 2D:4D finger-length ratio, a putative retrospective biomarker of prenatal testosterone exposure

The ratio of the lengths of an individual's second to fourth digit (2D:4D) is commonly used as a noninvasive retrospective biomarker for prenatal androgen exposure. In order to identify the genetic determinants of 2D:4D, we applied a genome-wide association approach to 1507 11-year-old children from the Avon Longitudinal Study of Parents and Children (ALSPAC) in whom 2D:4D ratio had been measured, as well as a sample of 1382 12- to 16-year-olds from the Brisbane Adolescent Twin Study. A meta-analysis of the two scans identified a single variant in the LIN28B gene that was strongly associated with 2D:4D (rs314277: p = 4.1 108) and was subsequently independently replicated in an additional 3659 children from the ALSPAC cohort (p = 1.53 106). The minor allele of the rs314277 variant has previously been linked to increased height and delayed age at menarche, but in our study it was associated with increased 2D:4D in the direction opposite to that of previous reports on the correlation between 2D:4D and age at menarche. Our findings call into question the validity of 2D:4D as a simplistic retrospective biomarker for prenatal testosterone exposure

Second-to-Fourth Digit Ratio Has a Non-Monotonic Impact on Altruism

Gene-culture co-evolution emphasizes the joint role of culture and genes for the emergence of altruistic and cooperative behaviors and behavioral genetics provides estimates of their relative importance. However, these approaches cannot assess which biological traits determine altruism or how. We analyze the association between altruism in adults and the exposure to prenatal sex hormones, using the second-to-fourth digit ratio. We find an inverted U-shaped relation for left and right hands, which is very consistent for men and less systematic for women. Subjects with both high and low digit ratios give less than individuals with intermediate digit ratios. We repeat the exercise with the same subjects seven months later and find a similar association, even though subjects' behavior differs the second time they play the game. We then construct proxies of the median digit ratio in the population (using more than 1000 different subjects), show that subjects' altruism decreases with the distance of their ratio to these proxies. These results provide direct evidence that prenatal events contribute to the variation of altruistic behavior and that the exposure to fetal hormones is one of the relevant biological factors. In addition, the findings suggest that there might be an optimal level of exposure to these hormones from social perspective.Financial support from the Spanish Ministry of Science and Innovation (ECO2010{17049; ECO2009-09120), the Government of Andalusia Project for Excellence in Research (P07.SEJ.02547), the Government of the Basque Country (IT-223–07) and Fundacion Ramon Areces (I+D-2011)is gratefully acknowledged

Callous-unemotional traits moderate the relation between prenatal testosterone (2D:4D) and externalising behaviours in children

Children who exhibit callous-unemotional (CU) traits are identified as developing particularly severe forms of externalising behaviours (EB). A number of risk factors have been identified in the development of CU traits, including biological, physiological, and genetic factors. However, prenatal testosterone (PT) remains un-investigated, yet could signal fetal programming of a combination of CU/EB. Using the 2D:4D digit ratio, the current study examined whether CU traits moderated the relationship between PT and EB. Hand scans were obtained from 79 children aged between 5 and 6 years old whose parents completed the parent report ICU (Inventory of Callous Unemotional Traits) and SDQ (Strengths and Difficulties Questionnaire). CU traits were found to moderate the relationship between PT and EB so that children who were exposed to increased PT and were higher in CU traits exhibited more EB. Findings emphasize the importance of recognising that vulnerability for EB that is accompanied by callousness may arise before birth

Overconfidence, incentives and digit ratio

This paper contributes to a better understanding of the biological underpinnings of overconfidence by analyzing performance predictions in the Cognitive Reflection Test with and without monetary incentives. In line with the existing literature we find that the participants are too optimistic about their performance on average; incentives lead to higher performance; and males score higher than females on this particular task. The novelty of this paper is an analysis of the relation between participants’ performance prediction accuracy and their second to fourth digit ratio. It has been reported that the digit ratio is a negatively correlated bio-marker of prenatal testosterone exposure. In the un-incentivized treatment, we find that males with low digit ratios, on average, are significantly more overconfident about their performance. In the incentivized treatment, however, we observe that males with low digit ratios, on average, are less overconfident about their performance. These effects are not observed in females. We discuss how these findings fit into the literature on testosterone and decision making and how they might help to explain seemingly opposing evidence

Face, body and speech cues independently predict judgments of attractiveness

Research on human attraction frequently makes use of single-modality stimuli such as neutral-expression facial photographs as proxy indicators of an individual’s attractiveness. However, we know little about how judgments of these single-modality stimuli correspond to judgments of stimuli that incorporate multi-modal cues of face, body and speech. In the present study, ratings of attractiveness judged from videos of participants introducing themselves were independently predicted by judgments of the participant’s facial attractiveness (a neutral-expression facial photograph masked to conceal the hairstyle), body attractiveness (a photograph of the upper body), and speech attractiveness (the soundtrack to the video). We also found that ratings of the face, body and speech were positively related to each other. Our results support the assumption that the single-modality stimuli used in much attractiveness research are valid proxy indicators of overall attractiveness in ecologically valid contexts, and complement literature showing cross-modality concordance of trait attractiveness, but also recommend that research relying on assessments of individual attractiveness take account of both visual and vocal attractiveness where possible

Social and health epidemiology of immigrants in Germany: past, present and future

Razum O, Wenner J. Social and health epidemiology of immigrants in Germany: past, present and future. Public Health Reviews. 2016;37(1): 4.Germany has experienced different forms of immigration for many decades. At the end of and after the Second World War, refugees, displaced persons and German resettlers constituted the largest immigrant group. In the 1950s, labor migration started, followed by family reunification. There has been a constant migration of refugees and asylum seekers reaching peaks in the early 1990s as well as today. Epidemiological research has increasingly considered the health, and the access to health care, of immigrants and people with migration background. In this narrative review we discuss the current knowledge on health of immigrants in Germany. The paper is based on a selective literature research with a focus on studies using representative data from the health reporting system. Our review shows that immigrants in Germany do not suffer from different diseases than non-immigrants, but they differ in their risk for certain diseases, in the resources to cope with theses risk and regarding access to treatment. We also identified the need for differentiation within the immigrant population, considering among others social and legal status, country of origin and duration of stay. Though most of the studies acknowledge the need for differentiation, the lack of data currently rules out analyses accounting for the existing diversity and thus a full understanding of health inequalities related to migration to Germany

Digit ratios have poor indicator value in a wild bird population

Early androgen exposure is known to have long-lasting effects on phenotype, behaviour and even fitness, but difficulties in measuring the exposure hinders the study of its importance in evolutionary context. Digit ratios have been highlighted as a potential easy-to-measure indicator of early steroid exposure, as they have been suggested to reflect steroid, mainly testosterone levels during prenatal development. However, evidence for digit ratios reflecting early steroid levels is weak, as experimental studies, especially in wild populations, are scarce. We studied the association between maternally derived yolk androgens and digit ratios (2D:4D, 2D:3D and 3D:4D) using both correlative data and a rather high level of experimental elevation of yolk androgens in a passerine bird, the pied flycatcher (Ficedula hypoleuca). We also examined whether digit ratios have indicator value in an evolutionary context by studying correlations between digit ratios and reproductive traits, secondary sexual traits and exploratory behaviour. We did not find any association between digit ratios and yolk androgen level either in correlative or experimental data. Digit ratios were neither related to any of the reproductive and secondary sexual traits or exploratory behaviour measured. There was, however, a sex difference in 2D:3D and 3D:4D of adult birds (due to second and fourth digits being shorter in females), which was not apparent in fledglings or captivity-raised juveniles. This suggests that either the sex difference may develop as late as during the sexual maturation for breeding. These results indicate that, in this species, digit ratios are not reliable markers of maternally derived yolk androgen exposure and that they bear little relevance as correlates of the adaptive traits we measured