Maternal effects on anogenital distance in a wild marmot population

Peer reviewedPublisher PD

Hand pattern indicates prostate cancer risk

BACKGROUND: The ratio of digit lengths is fixed in utero, and may be a proxy indicator for prenatal testosterone levels. METHODS: We analysed the right-hand pattern and prostate cancer risk in 1524 prostate cancer cases and 3044 population-based controls. RESULTS: Compared with index finger shorter than ring finger (low 2D : 4D), men with index finger longer than ring finger (high 2D : 4D) showed a negative association, suggesting a protective effect with a 33% risk reduction (odds ratio (OR) 0.67, 95% confidence interval (CI) 0.57-0.80). Risk reduction was even greater (87%) in age group <60 (OR 0.13, 95% CI 0.09-0.21). CONCLUSION: Pattern of finger lengths may be a simple marker of prostate cancer risk, with length of 2D greater than 4D suggestive of lower risk. British Journal of Cancer (2011) 104, 175-177. doi:10.1038/sj.bjc.6605986 www.bjcancer.com Published online 30 November 2010 (C) 2011 Cancer Research U

Selective Breeding for a Behavioral Trait Changes Digit Ratio

The ratio of the length of the second digit (index finger) divided by the fourth digit (ring finger) tends to be lower in men than in women. This 2D∶4D digit ratio is often used as a proxy for prenatal androgen exposure in studies of human health and behavior. For example, 2D∶4D ratio is lower (i.e. more “masculinized”) in both men and women of greater physical fitness and/or sporting ability. Lab mice have also shown variation in 2D∶4D as a function of uterine environment, and mouse digit ratios seem also to correlate with behavioral traits, including daily activity levels. Selective breeding for increased rates of voluntary exercise (wheel running) in four lines of mice has caused correlated increases in aerobic exercise capacity, circulating corticosterone level, and predatory aggression. Here, we show that this selection regime has also increased 2D∶4D. This apparent “feminization” in mice is opposite to the relationship seen between 2D∶4D and physical fitness in human beings. The present results are difficult to reconcile with the notion that 2D∶4D is an effective proxy for prenatal androgen exposure; instead, it may more accurately reflect effects of glucocorticoids, or other factors that regulate any of many genes

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

A Characterization of Internet Dating Network Structures among Nordic Men Who Have Sex with Men

Background: The Internet has become an important venue for seeking sexual partners and may facilitate transmission of sexually transmitted infections. Methods: We examined a 64-day data log of flirt messages expressing sexual interest among MSM within the Qruiser. com community. We used logistic regression to analyze characteristics of MSM sending and receiving flirt messages and negative binomial regression to examine individual activity and popularity. The structural properties, including the core structure of the flirt network, were analyzed. Results: The MSM population consisted of approximately 40% homosexuals and 37% bisexuals, while the remaining 23% included men who identified as heterosexual but searched for sex with men and "experimental". MSM were more likely to send flirt messages if they were homosexual and aged 40+ years; young people aged, 30 years were more likely to receive a flirt. Possession of a webcam was strongly associated with both sending flirt messages and being a flirt target. The distributions of flirts sent (max k(out) = 2162) and received (max k(in) = 84) were highly heterogeneous. Members in central cores were more likely homosexuals, singles, and aged 31-40 years. The probability of a matched flirt (flirt returned from target) increased from 1% in the outer core to 18% in the central core (core size = 4). Discussion: The flirt network showed high degree heterogeneity similar to the structural properties of real sexual contact networks with a single central core. Further studies are needed to explore use of webcam for Internet dating

Social behaviour shapes hypothalamic neural ensemble representations of conspecific sex

All animals possess a repertoire of innate (or instinctive1,2) behaviours, which can be performed without training. Whether such behaviours are mediated by anatomically distinct and/or genetically specified neural pathways remains unknown3,4,5. Here we report that neural representations within the mouse hypothalamus, that underlie innate social behaviours, are shaped by social experience. Oestrogen receptor 1-expressing (Esr1+) neurons in the ventrolateral subdivision of the ventromedial hypothalamus (VMHvl) control mating and fighting in rodents6,7,8. We used microendoscopy9 to image Esr1+ neuronal activity in the VMHvl of male mice engaged in these social behaviours. In sexually and socially experienced adult males, divergent and characteristic neural ensembles represented male versus female conspecifics. However, in inexperienced adult males, male and female intruders activated overlapping neuronal populations. Sex-specific neuronal ensembles gradually separated as the mice acquired social and sexual experience. In mice permitted to investigate but not to mount or attack conspecifics, ensemble divergence did not occur. However, 30 minutes of sexual experience with a female was sufficient to promote the separation of male and female ensembles and to induce an attack response 24 h later. These observations uncover an unexpected social experience-dependent component to the formation of hypothalamic neural assemblies controlling innate social behaviours. More generally, they reveal plasticity and dynamic coding in an evolutionarily ancient deep subcortical structure that is traditionally viewed as a ‘hard-wired’ system