Anabolic androgenic steroids differentially affect social behaviors in adolescent and adult male Syrian hamsters

Anabolic androgenic steroids (AAS) are synthetic derivatives of testosterone used by over half a million adolescents in the United States for their tissue-building potency and performance-enhancing effects. AAS also affect behavior, including reports of heightened aggression and changes in sexual libido. The expression of sexual and aggressive behaviors is a function of complex interactions among hormones, social context, and the brain, which is extensively remodeled during adolescence. Thus, AAS may have different consequences on behavior during adolescence and adulthood. Using a rodent model, these studies directly compared the effects of AAS on the expression of male sexual and aggressive behaviors in adolescents and adults. Male Syrian hamsters were injected daily for 14 days with either vehicle or an AAS cocktail containing testosterone cypionate (2 mg/kg), nandrolone decanoate (2 mg/kg), and boldenone undecylenate (1 mg/kg), either during adolescence (27-41 days of age) or in adulthood (63-77 days of age). The day after the last injection, males were tested for either sexual behavior with a receptive female or agonistic behavior with a male intruder. Adolescent males treated with AAS showed significant increases in sexual and aggressive behaviors relative to vehicle-treated adolescents. In contrast, AAS-treated adults showed significantly lower levels of sexual behavior compared with vehicle-treated adults and did not show heightened aggression. Thus, adolescents, but not adults, displayed significantly higher behavioral responses to AAS, suggesting that the still-developing adolescent brain is more vulnerable than the adult brain to the adverse consequences of AAS on the nervous system and behavior.     

HIV status and age at first marriage among women in Cameroon

Recent research has highlighted the risk of HIV infection for married teenage women compared with their unmarried counterparts (Clark, 2004). This study assesses whether a relationship exists, for women who have completed their adolescence (age 20-29 years), between HIV status with age at first marriage and the length of time between first sex and first marriage. Multivariate analysis utilizing the nationally representative 2004 Cameroon Demographic and Health Survey shows that late-marrying women and those with a longer period of pre-marital sex have the highest risk of HIV. Although women in urban areas overall marry later than their rural counterparts, the positive relationship between age at marriage and HIV risk is stronger in rural areas. The higher wealth status and greater number of lifetime sexual partners of late-marrying women contribute to their higher HIV risk. Given that the age at first marriage and the gap between first marriage and first sex have increased in recent years, focusing preventive efforts on late-marrying women will be of much importance in reducing HIV prevalence among females.     

Pirouettes: the rotational play of wild chimpanzees

A pirouette is a locomotor-rotational movement in which a young chimpanzee spins around in a (mostly) quadruped posture while advancing forward in a straight line. We addressed whether this behavior evolved as a practice of general athletic ability or of sexual selection. The former hypothesis would predict no sex differences in skill or the developmental process, while the latter would predict the opposite. Chimpanzees most likely master the pirouette around the time of weaning. We found no conspicuous sex differences in the developmental process or the number of rotations per bout of pirouettes, so the pirouette’s main function may be to facilitate general athletic ability. Infants pirouetted regardless of the context of rest or travel, whereas juveniles and adolescents pirouetted primarily during travel. This is consistent with the survival strategy hypothesis, because juveniles and adolescents would be expected to display pirouettes to many watchers if this practice were sexually selected. However, the fact that males tend to pirouette faster than females and to pirouette even during adolescence suggests that sexual selection has some influence in shaping the evolution of the practice. Despite this, no conspicuous tendency was found for juveniles or adolescent chimpanzees to display pirouettes to opposite-sex individuals. More data on adolescent individuals are needed to definitively determine the role of sex differences in pirouetting behavior.     

Acculturation process and its effects on dietary habits, nutritional behavior and body-image in adolescents

Previous studies have indicated that the acculturation process may contribute to psychosocial and health problems among immigrants through the mediation of acculturation stress. This study focuses on adolescents with immigrant background permanently settled in the Croatian region of Dalmatia and the influences of the acculturation process on their dietary habits, nutritional behavior and perceived body-image. The survey was conducted on the total sample of 510 adolescents (aged 14-19) including 52 first generation and 248 second generation immigrants. The analysis included dietary habits and questions of restrictive diet as indicators of unhealthy influence on physical health. Psychological factors (stress and self-esteem) have been found to be associated with dietary habits, diet behavior and dissatisfaction with body-image among adolescents with significant differences by immigrant status. Immigrant status is viewed as a risk factor for psychological distress and unhealthy dieting behavior. Research stresses the need to study the interaction between acculturation and health not only from an individual perspective, but also from the broader socio-ecological context of population subgroups.     

Longitudinal Trends in Obesity in the United States From Adolescence to the Third Decade of Life

No longitudinal analyses using national data have evaluated the increase in obesity from adolescence into early adulthood. We examined obesity incidence, persistence, and reversal in a nationally representative cohort of US teens followed into their early 30s, using measured height and weight data, in individuals enrolled in wave II (1996; 12–21 years), wave III (2001; 17–26 years), and wave IV (2008 early release data; 24–32 years) of the National Longitudinal Study of Adolescent Health (N = 8,675). Obesity was defined as a BMI ≥95th percentile of the 2000 Centers for Disease Control/National Center for Health Statistics growth charts or ≥30 kg/m² for individuals <20 years and ≥30 kg/m² in individuals ≥20 years. In 1996, 13.3% of adolescents were obese. By 2008, obesity prevalence increased to 36.1%, and was highest among non‐Hispanic black females (54.8%). Ninety percent of the obese adolescents remained obese in 2008. While annual obesity incidence did not decline in the total sample across the two study intervals (2.3% per year 1996–2001 vs. 2.2% per year 2001–2008), rates among white females declined (2.7 to 1.9% per year) and were highest among non‐Hispanic black and Hispanic females (3.8 and 2.7% per year, 1996–2001 vs. 3.0 and 2.6% per year, 2002–2008, respectively). Obesity prevalence doubled from adolescence to the early 20s, and doubled again from the early to late 20s or early 30s, with strong tracking from adolescence into adulthood. This trend is likely to continue owing to high rates of pediatric obesity. Effective preventive and treatment efforts are critically needed.     

Risk factors differ according to same-sex and opposite-sex interest

Are risk behaviours in adolescence differentiated according to same-sex vs opposite-sex interest? For all respondents a five-point scale of interest in each sex used information from both of the first two in-home waves of the National Longitudinal Study of Adolescent Health (Add Health). Logistic regression predicted the probability of experiencing each risk behaviour from the same-sex and opposite-sex interest scores. Same-sex interests have more effect on emotional risk, and opposite-sex interests have more effect on substance use. Nevertheless, all risk variables except boys' depression are responsive to both same-sex and opposite-sex interest. The same-sex interest component of risk is attributed to the emotional strain of living with an anomalous sex interest in a heterosexual society.     

Age- and sex-related variations in vocal-tract morphology and voice acoustics during adolescence

Distinct differences in the human voice emerge during adolescence, with males producing deeper and more resonant voices than females by the end of sexual maturation. Using magnetic resonance images of heads and voice recordings obtained in 532 typically developing adolescents, we investigate what might be the drivers of this change in voice, and the subjective judgment of the voice “maleness” and “femaleness”.We show clear sex differences in the morphology of voice-related structures during adolescence, with males displaying strong associations between age (and puberty) and both vocal-fold and vocal-tract length; this was not the case in female adolescents. At the same time, males (compared with females) display stronger associations between age (and puberty) with both fundamental frequency and formant position. In males, vocal morphology was a mediator in the relationship between bioavailable testosterone and acoustic indices.Subjective judgment of the voice sex could be predicted by the morphological and acoustic parameters in males only: the length of vocal folds and its acoustic counterpart, fundamental frequency, is a larger predictor of subjective “maleness” of a voice than vocal-tract length and formant position.     

Effects of suppressing gonadal hormones on response to novel objects in adolescent rats

Human adolescents exhibit higher levels of novelty-seeking behaviour than younger or older individuals, and novelty-seeking is higher in males than females from adolescence onwards. Gonadal hormones, such as testosterone and estradiol, have been suggested to underlie age and sex difference in response to novelty; however, empirical evidence in support of this hypothesis is limited. Here, we investigated whether suppressing gonadal hormone levels during adolescence affects response to novelty in laboratory rats. Previously, we have shown that male adolescent Lister-hooded rats (postnatal day, pnd, 40) exhibit a stronger preference than same-aged females for a novel object compared to a familiar object. In the current study, 24 male and 24 female Lister-hooded rats were administered with Antide (a gonadotrophin-releasing hormone antagonist), or with a control vehicle solution, at pnd 28. Antide provided long-term suppression of gonadal hormone production, as confirmed by ELISA assays and measurement of internal organs. Response to novel objects was tested at pnd 40 in Antide-treated and control subjects using a ‘novel object recognition’ task with a short (2-minute) inter-trial interval. In support of previous findings, control males exhibited a stronger preference than control females for novelty when presented with a choice of objects. Antide-treated males exhibited a significantly lower preference for novel objects compared to control males, whilst Antide-treated females did not differ significantly from control females in their preference for novelty. Antide treatment did not affect total time spent interacting with objects. We discuss how gonadal hormones might influence sex differences in preference for novelty during adolescence.     

Effects of suppressing gonadal hormones on response to novel objects in adolescent rats

Human adolescents exhibit higher levels of novelty-seeking behaviour than younger or older individuals, and novelty-seeking is higher in males than females from adolescence onwards. Gonadal hormones, such as testosterone and estradiol, have been suggested to underlie age and sex difference in response to novelty; however, empirical evidence in support of this hypothesis is limited. Here, we investigated whether suppressing gonadal hormone levels during adolescence affects response to novelty in laboratory rats. Previously, we have shown that male adolescent Lister-hooded rats (postnatal day, pnd, 40) exhibit a stronger preference than same-aged females for a novel object compared to a familiar object. In the current study, 24 male and 24 female Lister-hooded rats were administered with Antide (a gonadotrophin-releasing hormone antagonist), or with a control vehicle solution, at pnd 28. Antide provided long-term suppression of gonadal hormone production, as confirmed by ELISA assays and measurement of internal organs. Response to novel objects was tested at pnd 40 in Antide-treated and control subjects using a ‘novel object recognition’ task with a short (2-minute) inter-trial interval. In support of previous findings, control males exhibited a stronger preference than control females for novelty when presented with a choice of objects. Antide-treated males exhibited a significantly lower preference for novel objects compared to control males, whilst Antide-treated females did not differ significantly from control females in their preference for novelty. Antide treatment did not affect total time spent interacting with objects. We discuss how gonadal hormones might influence sex differences in preference for novelty during adolescence.     

Research for Change versus Research as Change: Lessons from a Mujerista Participatory Research Team

In this article, I aim to further the discussion of engaged research in anthropology and education by examining the unique changes promoted by participatory research in contrast to policy-oriented activist research models. Drawing on my work with Latina immigrant mothers in a school reform movement, I argue for a Latina feminist view of participatory research that illuminates and builds on Latina women's capacities for social critique and transformative resistance.  [participatory research, activist anthropology, Latino parents, school reform]     

Possible evolutionary origins of human female sexual fluidity

I propose an evolutionary theory of human female sexual fluidity and argue that women may have been evolutionarily designed to be sexually fluid in order to allow them to have sex with their cowives in polygynous marriage and thus reduce conflict and tension inherent in such marriage. In addition to providing an extensive definition and operationalization of the concept of sexual fluidity and specifying its ultimate function for women, the proposed theory can potentially solve several theoretical and empirical puzzles in evolutionary psychology and sex research. Analyses of the National Longitudinal Study of Adolescent Health (Add Health) confirm the theory's predictions that: (i) women (but not men) who experience increased levels of sexual fluidity have a larger number of children (suggesting that female sexual fluidity, if heritable, may be evolutionarily selected); (ii) women (but not men) who experience marriage or parenthood early in adult life subsequently experience increased levels of sexual fluidity; and (iii) sexual fluidity is significantly positively correlated with known markers of unrestricted sexual orientation among women whereas it is significantly negatively correlated with such markers among men.     

Participation in organized activities among Mexican and other Latino youth in Los Angeles: Variation by mother’s documentation status and youth’s age

Abstract

Although organized activities promote positive youth development, Latina/os are least likely to participate among ethnic minority youth. This study tested whether an indicator of social stratification, namely mothers’ documentation status (i.e., nativity, citizenship, and legal status), explained low activity participation rates among Mexican and other Latino youth. As a secondary goal, this study tests competing hypotheses about whether the relation between documentation status and participation varied by youth age. Using Los Angeles Family and Neighborhood Survey data, regression results indicated that Latino youth with unauthorized immigrant mothers were significantly less likely to participate in organized activities than those with native-born mothers, controlling for other variables. Post-estimation analyses indicated that participation gaps associated with mothers’ documentation status were larger for older than younger Latino youth. These findings suggest that documentation may function on a developmental continuum and that there was a developmental amplification of the effects of parents’ documentation status on youth activity participation.AQ3     

The Gamesmanship of Sex: A Model Based on African American Adolescent Accounts

This article examines adolescent understanding of the social context of sexual behavior. Using grounded theory to interpret interviews with 39 African American male and female adolescents, the article builds a model of sex-related behavior as a set of interrelated games. A courtship game involves communication of sexual or romantic interest and, over time, formation of a romantic relationship. A duplicity game draws on conventions of a courtship game to trick a partner into having sex. A disclosure game spreads stories about one's own and others' sex-related activities to peers in a gossip network. Finally, a prestige game builds social reputation in the eyes of peers, typically based on gender-specific standards. The article concludes by examining the meanings that sex-related behavior may have for adolescents and the potential use of social know ledge for facilitating adolescent health, [adolescence, sexuality, African American, game theory, health promotion]     

Ideological Whitening: does skintone shape colour-blind ideology adherence for Latina/os?

Prominent theories of the US racial order contend that phenotypically light Latina/os will elevate to an honorary White category as a result of their socio-economic advantages over darker Latina/os. Accordingly, light Latina/os are presumed to adopt colour-blind racial ideology to cement their elevated racial status. This study is among the first to examine the relationship between skintone and Latina/os’ colour-blind ideology adherence with nationally representative data. I examine these relationships with data from the 2006 Portraits of American Life Study, and test the robustness of findings across two alternative national data sets: the 2014 General Social Survey, and the 2006 Latino National Survey. Across data sets, different measurement approaches, and time periods, this study finds no evidence that skintone shapes Latina/os’ levels of colour-blind ideology adherence. The study concludes by considering why the racial ideology of light Latina/os is non-concordant with their elevated socio-economic status in relation to darker Latina/os.     

Sexual Orientation Disparities in Weight Status in Adolescence: Findings From a Prospective Study

A growing number of studies among adult women have documented disparities in overweight adversely affecting lesbian and bisexual women, but few studies have examined sexual orientation–related patterns in weight status among men or adolescents. We examined sexual orientation group trends in BMI (kg/m²), BMI Z‐scores, and overweight using 56,990 observations from 13,785 adolescent females and males in the Growing Up Today Study (GUTS), a large prospective cohort of US youth. Participants provided self‐reported information from six waves of questionnaire data collection from 1998 to 2005. Gender‐stratified linear regression models were used to estimate BMI and BMI Z‐scores and modified Poisson regression models to estimate risk ratios for overweight, controlling for age and race/ethnicity, with heterosexuals as the referent group. Among females, we observed fairly consistently elevated BMI in all sexual orientation minority groups relative to heterosexual peers. In contrast, among males we documented a sexual‐orientation‐by‐age interaction indicating steeper increases in BMI with age from early‐to‐late adolescence in heterosexuals relative to sexual orientation minorities. Additional prospective research is needed to understand the determinants of observed sexual orientation disparities and to inform appropriate preventive and treatment interventions. The long‐term health consequences of overweight are well‐documented and over time are likely to exact a high toll on populations with elevated rates.     

Pairing Patterns in Japanese Beetles (Popillia japonica Newman): Effects of Sex Ratio and Time of Day

Size-related patterns between unpaired and paired individuals and between males and females of a given pair give clues about both a species' sexual behavior and the environmental factors affecting its sexual behavior. We studied the mating patterns of Japanese beetles (Popillia japonica) in east–central Illinois. The frequency of male–female pairs varied significantly among days and within a day, with pairs being significantly more common in the morning and the evening. The sex ratio on the food plants was significantly male biased, but although the sex ratio fluctuated among days and among time periods, the variation in the frequency of mating pairs was not explained by variation in the sex ratio. We found no assortative pairing with respect to size, but sizes of paired and unpaired individuals did differ. Paired females were larger than unpaired females at all time periods. In contrast, paired males were larger at 0700 and smaller at 1000, and little difference existed at other times of the day. The size of males and females, sex ratio, and pairing frequency also differed among days. Much of this variation in size and pairing frequency was related to a seasonal effect: later in the summer, beetles of both sexes were smaller and pairs were less common. Interestingly, pairs were also less frequent on days with higher average temperatures. This between-day variation in pairing, in combination with the within-day pairing differences, suggests that the temperature may alter the cost, and hence likelihood, of pairing in this species.     

Genetic Epidemiology of BMI and Body Mass Change From Adolescence to Young Adulthood

The complex interplay between genes and environment affecting body mass gain over lifecycle periods of risk is not well understood. We use longitudinal sibling cohort data to examine the role of shared household environment, additive genetic, and shared genetic effects on BMI and BMI change. In the National Longitudinal Study of Adolescent Health, siblings and twin pairs sharing households for ≥10 years as adolescents (N = 5,524; mean = 16.5 ± 1.7 years) were followed into young adulthood (N = 4,368; mean = 22.4 ± 1.8 years). Using a variance component approach, we quantified genetic and household effects on BMI in siblings and nonsiblings sharing household environments over time. Adjusting for race, age, sex, and age‐by‐sex interaction, we detected a heritability of 0.43 ± 0.05 for BMI change. Significant household effects were noted during the young adulthood period only (0.11 ± 0.06). We find evidence for shared genetic effects between BMI and BMI change during adolescence (genetic correlation (ρ_G) = 0.61 ± 0.03) and young adulthood (ρ_G = 0.23 ± 0.06). Our findings support a complex etiology of BMI and BMI change.     

The Role of Courtship Behavior and Size in Mate Preference in the Sex‐Role‐Reversed Gulf Pipefish,Syngnathus scovelli

In sex‐role‐reversed species, sexual selection acts more strongly on females than on males, a situation that can result in the evolution of secondary sexual traits in females and strong mating preferences in males. While some research exploring mating preferences in sex‐role‐reversed species has been conducted, overall, this topic remains relatively unexplored. The Gulf pipefish, Syngnathus scovelli, is a highly polyandrous pipefish species. Sexual selection is significantly stronger in females than in males, which has led to the evolution of both morphological and behavioral female secondary sexual traits. However, because males gestate the offspring in specialized pouches and make a substantial investment in embryos during development, females may also benefit from being choosy. The goal of this study was to examine both male and female mating preferences in this species. We found that male mating preference was significantly associated with female courtship behavior. Larger females were also able to maintain these behaviors for longer intervals than smaller females. No evidence of female mating preference in regard to male size was observed but the data suggest that male behaviors may be providing positive reinforcement to courting females. This research provides further insight into how mate preferences vary among sex‐role‐reversed species.     

Fluoride in drinking water and osteosarcoma incidence rates in the continental United States among children and adolescents

IntroductionIt has been suggested that fluoride in drinking water may increase the risk of osteosarcoma in children and adolescents, although the evidence is inconclusive. We investigated the association between community water fluoridation (CWF) and osteosarcoma in childhood and adolescence in the continental U.S.MethodsWe used the cumulative osteosarcoma incidence rate data from the CDC Wonder database for 1999–2006, categorized by age group, sex and states. States were categorized as low (≤30%) or high (≥85%) according to the percentage of the population receiving CWF between 1992 and 2006. Confidence intervals for the incidence rates were calculated using the Gamma distribution and the incidence rates were compared between groups using Poisson regression models.ResultsWe found no sex-specific statistical differences in the national incidence rates in the younger groups (5–9, 10–14), although 15–19 males were at higher risk to osteosarcoma than females in the same age group (p < 0.001). Sex and age group specific incidence rates were similar in both CWF state categories. The higher incidence rates among 15–19 year old males vs females was not associated with the state fluoridation status. We also compared sex and age specific osteosarcoma incidence rates cumulated from 1973 to 2007 from the SEER 9 Cancer Registries for single age groups from 5 to 19. There were no statistical differences between sexes for 5–14 year old children although incidence rates for single age groups for 15–19 year old males were significantly higher than for females.ConclusionOur ecological analysis suggests that the water fluoridation status in the continental U.S. has no influence on osteosarcoma incidence rates during childhood and adolescence.