Adolescent anabolic/androgenic steroids: Aggression and anxiety during exposure predict behavioral responding during withdrawal in Syrian hamsters (Mesocricetus auratus)

In the U.S. and worldwide anabolic/androgenic steroid use remains high in the adolescent population. This is concerning given that anabolic/androgenic steroid use is associated with a higher incidence of aggressive behavior during exposure and anxiety during withdrawal. This study uses pubertal Syrian hamsters (Mesocricetus auratus) to investigate the hypothesis that an inverse behavioral relationship exists between anabolic/androgenic steroid-induced aggression and anxiety across adolescent exposure and withdrawal. In the first experiment, we examined aggression and anxiety during adolescent anabolic/androgenic steroid exposure and withdrawal. Adolescent anabolic/androgenic steroid administration produced significant increases in aggression and decreases in anxiety during the exposure period followed by significant decreases in aggression and increases in anxiety during anabolic/androgenic steroid withdrawal. In a second experiment, anabolic/androgenic steroid exposed animals were separated into groups based on their aggressive response during the exposure period and then tested for anxiety during exposure and then for both aggression and anxiety during withdrawal. Data were analyzed using a within-subjects repeated measures predictive analysis. Linear regression analysis revealed that the difference in aggressive responding between the anabolic/androgenic steroid exposure and withdrawal periods was a significant predictor of differences in anxiety for both days of testing. Moreover, the combined data suggest that the decrease in aggressive behavior from exposure to withdrawal predicts an increase in anxiety-like responding within these same animals during this time span. Together these findings indicate that early anabolic/androgenic steroid exposure has potent aggression- and anxiety-eliciting effects and that these behavioral changes occur alongside a predictive relationship that exists between these two behaviors over time.     

Seasonal Variation in Response to Neighbors and Strangers by a Territorial Songbird

Reduced aggression toward territorial neighbors, termed the ‘dear‐enemy’ effect, is thought to arise because territorial animals benefit by avoiding contests with neighbors with whom they have already established relationships. The dear‐enemy effect has been described in many taxa, but few studies have considered whether or not neighbors’ relationships are affected by changes in the social environment. In this study, I tested whether Carolina wrens, Thryothorus ludovicianus, behaviorally discriminate between neighbors and strangers in two different social environments: in spring when territories have been established for several months, and in fall when an influx of new birds claiming territories might de‐stabilize wren neighborhoods. Comparisons of responses of territorial males to playbacks of songs from neighbors and strangers showed that Carolina wrens show the dear‐enemy effect in spring, but not in fall in this design. The apparent lack of a differential response to neighbors and strangers in fall might be due to a reduction in aggression toward strangers. This study provides evidence that seasonal changes in the dear‐enemy effect coincide with seasonal changes in the social environment.     

Territorial aggression, circulating levels of testosterone, and brain aromatase activity in free-living pied flycatchers

Testosterone (T) is a critical endocrine factor for the activation of many aspects of reproductive behavior in vertebrates. Castration completely eliminates the display of aggressive and sexual behaviors that are restored to intact level by a treatment with exogenous T. There is usually a tight correlation between the temporal changes in plasma T and the frequency of reproductive behaviors during the annual cycle. In contrast, individual levels of behavioral activity are often not related to plasma T concentration at the peak of the reproductive season suggesting that T is available in quantities larger than necessary to activate behavior and that other factors limit the expression of behavior. There is some indication from work in rodents that individual levels of brain aromatase activity (AA) may be a key factor that limits the expression of aggressive behavior, and in agreement with this idea, many studies indicate that estrogens produced in the brain by the aromatization of T may contribute to the activation of reproductive behavior, including aggression. We investigated here in pied flycatcher (Ficedula hypoleuca) the relationships among territorial aggression, plasma T, and brain AA at the peak of the reproductive season. In a first experiment, blood samples were collected from unpaired males holding a primary territory and, 1 or 2 days later, their aggressive behavior was quantified during standardized simulated territorial intrusions. No relationship was found between individual differences in aggressive behavior and plasma T or dihydrotestosterone levels but a significant negative correlation was observed between number of attacks and plasma corticosterone. In a second experiment, aggressive behavior was measured during a simulated territorial intrusion in 22 unpaired males holding primary territories. They were then immediately captured and AA was measured in their anterior and posterior diencephalon and in the entire telencephalon. Five males that had attracted a female (who had started egg-laying) were also studied. The paired males were less aggressive and correlatively had a lower AA in the anterior diencephalon but not in the posterior diencephalon and telencephalon than the 22 birds holding a territory before arrival of a female. In these 22 birds, a significant correlation was observed between number of attacks/min displayed during the simulated territorial intrusion and AA in the anterior diencephalon but no correlation was found between these variables in the two other brain areas. Taken together, these data indicate that the level of aggression displayed by males defending their primary territory may be limited by the activity of the preoptic aromatase, but plasma T is not playing an important role in establishing individual differences in aggression. Alternatively, it is also possible that brain AA is rapidly affected by agonistic interactions and additional work should be carried out to determine whether the correlation observed between brain AA and aggressive behavior is the result of an effect of the enzyme on behavior or vice versa. In any case, the present data show that preoptic AA can change quite rapidly during the reproductive cycle (within a few days after arrival of the female) indicating that this enzymatic activity is able to regulate rapid behavioral transitions during the reproductive cycle in this species.     

The effects of castration and Silastic implants of testosterone on intermale aggression in the mouse

Castration and testosterone (T) replacement were used to study developmental changes in aggressive behavioral responsiveness to androgenic stimulation. Male mice castrated at birth were less sensitive to circulating T than were prepubertal or adult castrates, but fighting was induced in neonatal castrates with a dose of androgen that produced hypertrophy of the accessory organ system in adult castrates. Gonadectomy shortly prior to pubertal increases in serum T concentration also reduced behavioral responsiveness to androgen administration. Intermale aggression was induced in prepubertal castrates only with T treatment that maintained accessory organ growth in adult castrates. The aggressive behavior of males castrated after the pubertal surge in serum T was supported with circulating levels of androgen that failed to stimulate the accessory organ system above that of oil-treated castrates. It was concluded that T stimulation during neonatal or pubertal life is not totally crucial for organization of neural substrates that mediate the ultimate expression of intermale aggression, but exposure to androgen from birth throughout pubertal development is normally required to produce maximal aggressive behavioral responsiveness to circulating T encountered in adulthood.     

The development of affiliative and coercive reproductive tactics in male chimpanzees

Like many animals, adult male chimpanzees often compete for a limited number of mates. They fight other males as they strive for status that confers reproductive benefits and use aggression to coerce females to mate with them. Nevertheless, small-bodied, socially immature adolescent male chimpanzees, who cannot compete with older males for status nor intimidate females, father offspring. We investigated how they do so through a study of adolescent and young adult males at Ngogo in Kibale National Park, Uganda. Adolescent males mated with nulliparous females and reproduced primarily with these first-time mothers, who are not preferred as mating partners by older males. Two other factors, affiliation and aggression, also influenced mating success. Specifically, the strength of affiliative bonds that males formed with females and the amount of aggression males directed toward females predicted male mating success. The effect of male aggression toward females on mating success increased as males aged, especially when they directed it toward females with whom they shared affiliative bonds. These results mirror sexual coercion in humans, which occurs most often between males and females involved in close, affiliative relationships.     

Reproductive Consequences of Aggression in a Territorial Songbird

Territorial aggression can influence males’ ability to obtain high‐quality resources and access to mates; however, in many species, the reproductive consequences of variation in aggression are unknown. In this study, we investigated how individual variation in aggressive behavior relates to reproductive success in socially monogamous, genetically polygynous song sparrows (Melospiza melodia). Prior research in this species shows that male song sparrows differ in their willingness to engage in agonistic interactions with territorial intruders and that individual variation in aggression appears to have functional significance. Aggressive males have been shown to obtain territories where females produce larger clutch sizes, suggesting that individuals who display high levels of territorial aggression are defending high‐quality territories or females. Further, aggressive males are considered a greater threat to territory‐holding males than less aggressive males. In this study, we ask whether individual differences in aggression are linked to differences in extra‐pair reproductive success, annual reproductive success, and offspring quality. We did not uncover a relationship between aggression and annual reproductive success or patterns of extra‐pair paternity. However, we found that the nestlings of aggressive males grew at a faster rate than the nestlings of less aggressive males. Future studies should attempt to identify mechanisms to explain the relationship between offspring growth rate and male aggression and investigate whether faster offspring growth rates translate to greater survival and recruitment of offspring.     

Correlated effects of the Y-chromosome of mice on developmental changes in testosterone levels and intermale aggression.

Serum testosterone (T) was studied developmentally in DBA/1/Bg and C57BL/10/Bg inbred mice, as well as in their reciprocal F1 hybrids. Testosterone determinations were made using a radioimmunoassay. At 35 and 40 days $\text{post partum}$, DBA/1/Bg mice had higher levels of T than C57BL/10/Bg males. Comparison of the regression coefficients for the serum T values over days 30, 35, 40, and 50 also indicated statistical differences in the two curves of developmental changes in T. The pubertal rise in B10D1F1 but not D1B10F1 males was found to be steeper in slope over days 30, 35, 40, and 50 than that of C57BL/10/Bg males. These data suggest that during the pubertal period there may be a more rapid increase in serum T titer associated with the DBA/1 Y-chromosome. However, the developmental curves of T for the two reciprocal hybrids were not statistically different from each other or from that of the DBA/1/Bg males. These findings are suggestive of a Y-chromosome effect on developmental changes in T and of a genetic correlation with intermale aggression.     

Sex differences in 2D:4D and aggression in children and adolescents from five regions of Russia

The aim of this study was to consider digit ratio (2D:4D: a putative marker of prenatal testosterone and estrogen levels) and aggression in a sample of 1,452 children and adolescents (mean age 13.6 years) from five regions of Russia. The 2D:4D was calculated from direct measurements of the fingers, and aggression scores were obtained from completed Buss and Perry (J Pers Soc Psychol 63 (1992) 452–459) aggression questionnaires. The 2D:4D demonstrated significant sexual dimorphism, with lower 2D:4D in boys in all regions. Physical aggression scores were highest in boys, but verbal aggression, anger and hostility were highest in girls. The highest right hand 2D:4D in boys was found in the most northerly population (Central Russia Region). Our data revealed small, but highly significant negative correlations between right 2D:4D, right–left 2D:4D (D_R‐L) and self‐ratings on physical aggression in boys, but not in girls. These relationships remained after considering Russian ethnics only, and controlling for region. We suggest that the associations may be due to sex differences in prenatal androgen secretion. Am J Phys Anthropol 152:130–139, 2013. © 2013 Wiley Periodicals, Inc.     

The effects of competition and implicit power motive on men's testosterone,emotion recognition,and aggression

A contribution to a special issue on Hormones and Human Competition.We investigated the effects of competition on men's testosterone levels and assessed whether androgen reactivity was associated with subsequent emotion recognition and reactive and proactive aggression. We also explored whether personalized power (p Power) moderated these relationships. In Study 1, 84 males competed on a number tracing task and interpreted emotions from facial expressions. In Study 2, 72 males competed on the same task and were assessed on proactive and reactive aggression. In both studies, contrary to the biosocial model of status (Mazur, 1985), winners' testosterone levels decreased significantly while losers' levels increased, albeit not significantly. Personalized power moderated the effect of competition outcome on testosterone change in both studies. Using the aggregate sample, we found that the effect of decreased testosterone levels among winners (compared to losers) was significant for individuals low in p Power but not for those with medium or high p Power. Testosterone change was positively related to emotion recognition, but unrelated to either aggression subtype. The testosterone-mediated relationship between winning and losing and emotion recognition was moderated by p Power. In addition, p Power moderated the direct (i.e., non-testosterone mediated) path between competition outcome and emotion recognition and both types of aggression: high p-Power winners were more accurate at deciphering others' emotions than high p-Power losers. Finally, among high p-Power men, winners aggressed more proactively than losers, whereas losers aggressed more reactively than winners. Collectively, these studies highlight the importance of implicit power motivation in modulating hormonal, cognitive, and behavioral outcomes arising from human competition.     

Social parameters and urinary testosterone level in male chimpanzees (Pan troglodytes)

Studies investigating relationships between social parameters (such as dominance rank, rates of aggressive and sexual behaviors) and androgen (particularly, testosterone) levels in male primates have yielded inconsistent results. In the present study, we address the relationship between androgens, male dominance rank and rank-associated behaviors in two groups of captive chimpanzees, a species characterized by a pronounced dominance hierarchy between adult males. By combining behavioral observations with urinary testosterone (T) measurements, we found that the differences in T concentrations between males were small and not obviously related to their dominance rank. T levels were not related to the rates of initiated aggression and copulatory behavior, but a significant negative relationship between male T level and the rates of strong aggression received was apparent. Our findings, combined with those of others, suggest that any relationship between dominance rank and T depends upon the extent to which individual rank-associated behaviors (e.g. aggressive/sexual) are themselves related to T.     

Information on Resource Quality Mediates Aggression between Male Madagascar Hissing Cockroaches, Gromphadorhina portentosa (Dictyoptera: Blaberidae)

Male Madagascar hissing cockroaches, Gromphadorhina portentosa Schaum (Dictyoptera: Blaberidae) have a well‐defined dominance hierarchy that has been assumed to explain the outcome of most competitive interactions. We studied whether males of this species would alter their level of aggression towards unfamiliar rivals as a function of changing resource availability and value – two factors that are key to aggression levels in non‐hierarchical species. We quantified male aggression as three variables (aggressive state – behaviours measured by their duration; aggressive act – behaviours measured by their frequency of occurrence; aggressive latency – the latency to first aggressive behaviour, either state or act) and tested for any context‐specific variation within each by manipulating both territorial status (males were either residents or intruders) and access to mates (female present or absent). Both the presence of a female and territorial status affected male aggression towards rivals as measured by duration of aggressive state. Highest levels of aggression were displayed by residents when a female was present. These results show that inter‐male aggression in G. portentosa is tuned to the immediate expected payoff from fighting, and not exclusively aimed at establishing dominance relationships (which can affect future payoffs).     

Hormone Replacement Therapy in Children with Hypogonadotropic Hypogonadism: Where do we Stand?

ObjectiveTo characterize hormone replacement therapy in a cohort of adolescent males and females with hypo-gonadotropic hypogonadism (HH) with a focus on changes in management during the past 10 years.MethodsMedical records of patients followed for HH during the past 10 years were reviewed.ResultsA total of 45 patients (22 female: 23 male) with HH were identified. The average age at HH diagnosis was 14.48 ± 2.02 years in females and 14.89 ± 1.64 years in males (P = .53). In females, the average age of pubertal induction was 14.53 ± 1.86 years. Conjugated equine estrogen was used in 54.5%, transdermal estradiol in 41%, and oral estradiol in 4.5%. The average duration to cycling was 1.96 ± 0.78 years. A progressive increase in the use of transdermal estradiol was noted over time, with 100% of females being started on this regimen since 2008. In males, the average age of induction was 15.22 ± 1.41 years. All were started on intramuscular testosterone cypionate at various doses. The average duration to full adult replacement was 1.95 ± 0.51 years.ConclusionThere is no current standard of care to guide pubertal induction in adolescents with HH. However, a significant increase in the use of transdermal estrogen was noted in females during the past 10 years. While much less variability in pubertal induction was seen in males, wide disparities in doses and escalation schedules were found. Prospective studies aimed at elucidating optimal strategies for sex steroid replacement in this pediatric population are badly needed. (Endocr Pract. 2013;19:968-971)     

Physical provocation of pubertal anabolic androgenic steroid exposed male rats elicits aggression towards females

Human studies suggest that anabolic androgenic steroid (AAS) users are aggressive towards women. This study used a rat model to evaluate whether AAS potentiated aggression towards females and the conditions under which this occurs. Gonadally intact pubertal male rats received one of the following AAS treatments (5 mg/kg s.c. 5 days/week for nine weeks): testosterone (T), stanozolol (S), testosterone + stanozolol (T + S), or vehicle control. Each rat was tested with 3 conspecific stimuli: ovariectomized females (OVX), estrogen only females (E), and estrogen + progesterone females (E + P). The response to physical provocation was tested under three conditions: without physical provocation, provocation of the experimental male, and provocation of the conspecific female. Provocation was a mild tail pinch. Both aggressive and sexual behaviors were measured during each test. In the absence of physical provocation, AAS males were not aggressive towards females. However, provocation significantly increased aggression in males treated with testosterone but only towards OVX females. In the presence of E or E + P females, all animals displayed sex behavior, not aggression. Thus, factors such as the nature of the AAS and the hormonal status of the females are important in determining whether male rats will be aggressive towards females. However, the most salient factor determining aggression towards females is the presence of provocation in combination with high levels of testosterone.     

Androgen‐metabolizing enzymes show region‐specific changes across the breeding season in the brain of a wild songbird

The Lapland longspur (Calcarius lapponicus) is an arctic‐breeding songbird that shows rapid behavioral changes during a short breeding season. Changes in plasma testosterone (T) in the spring are correlated with singing but not territorial aggression in males. Also, T treatment increases song but not aggression in this species. In contrast, in temperate‐zone breeders, song and aggression are highly correlated, and both increase after T treatment. We asked whether regional or temporal differences in androgen‐metabolizing enzymes in the longspur brain explain hormone‐behavior patterns in this species. We measured the activities of aromatase, 5α‐reductase and 5β‐reductase in free‐living longspur males. Aromatase and 5α‐reductase convert T into the active steroids 17β‐estradiol (E₂) and 5α‐dihydrotestosterone (5α‐DHT), respectively. 5β‐Reductase deactivates T via conversion to 5β‐DHT, an inactive steroid. We examined seven brain regions at three stages in the breeding season. Overall, aromatase activity was high in the hypothalamus, hippocampus, and ventromedial telencephalon (containing nucleus taeniae, the avian homologue to the amygdala). 5β‐Reductase activity was high throughout the telencephalon. Activities of all three enzymes changed over time in a region‐specific manner. In particular, aromatase activity in the rostral hypothalamus was decreased late in the breeding season, which may explain why T treatment at this time does not increase aggression. Changes in 5β‐reductase do not explain the effects of plasma T on aggressive behavior. © 1999 John Wiley & Sons, Inc. J Neurobiol 41: 176–188, 1999     

Social compatibility in a newly formed all‐male group of white crowned mangabeys (Cercocebus atys lunulatus)

Surplus males in primate captive populations are a common problem for zoos. Some captive breeding programs promote all‐male groups as an adequate option to house surplus males, but there have been few attempts to assess the feasibility of this management technique across primate species. The present study provides preliminary data regarding social compatibility within a newly formed all‐male group of four white crowned mangabeys (Cercocebus atys lunulatus). The study was conducted at the Valencia Zoo (Spain), where data on social behavior were collected over 6 months using continuous focal animal sampling for a total of 87 hr of observation. Results show that low intensity aggressive behaviors (facial threats) were expressed at high rates, whereas physical aggression (fights) rarely occurred. Aggression was more frequent among individuals belonging to the same age–gender class. Regarding affiliative behaviors, every individual actively sought proximity to all other group members through positive approaches, and although not all males carried out social grooming, every male was groomed by at least one group member. Our results suggest that the group was compatible socially because social relationships among the individuals were not neutral, and physical aggression occurred at low rates. The present study provides preliminary data supporting the feasibility of all‐male groups as a management option for surplus males in captive populations of white crowned mangabeys. Nevertheless, further studies are needed to be able to generalize both within and across species. Zoo Biol 0:1–7, 2007. © 2006 Wiley‐Liss, Inc.     

Adolescents and androgens, receptors and rewards

Adolescence is associated with increases in pleasure-seeking behaviors, which, in turn, are shaped by the pubertal activation of the hypothalamo-pituitary-gonadal axis. In animal models of naturally rewarding behaviors, such as sex, testicular androgens contribute to the development and expression of the behavior in males. To effect behavioral maturation, the brain undergoes significant remodeling during adolescence, and many of the changes are likewise sensitive to androgens, presumably acting through androgen receptors (AR). Given the delicate interaction of gonadal hormones and brain development, it is no surprise that disruption of hormone levels during this sensitive period significantly alters adolescent and adult behaviors. In male hamsters, exposure to testosterone during adolescence is required for normal expression of adult sexual behavior. Males deprived of androgens during puberty display sustained deficits in mating. Conversely, androgens alone are not sufficient to induce mating in prepubertal males, even though brain AR are present before puberty. In this context, wide-spread use of anabolic-androgenic steroids (AAS) during adolescence is a significant concern. AAS abuse has the potential to alter both the timing and the levels of androgens in adolescent males. In hamsters, adolescent AAS exposure increases aggression, and causes lasting changes in neurotransmitter systems. In addition, AAS are themselves reinforcing, as demonstrated by self-administration of testosterone and other AAS. However, recent evidence suggests that the reinforcing effects of androgens may not require classical AR. Therefore, further examination of interactions between androgens and rewarding behaviors in the adolescent brain is required for a better understanding of AAS abuse.     

Modification of aggression through socialization and the special case of adult and adolescent male rhesus monkeys (Macaca mulatta)

Significant differences exist in the frequencies with which age-sex classes of rhesus macaques engage in agonistic interactions with other age-sex classes. In the study reported here, individuals engaged in significantly more agonistic interactions within their own age-sex classes, but, adult females also showed significantly more aggression toward infants and young females whereas adult males directed significantly more aggression toward adolescent males. Infants directed aggression toward infants of both sexes, but adults showed significantly less aggression toward adults of the opposite sex. These findings are hypothesized to reflect (1) competitive conflict among those individuals in the group most similar to each other (members of the same age-sex class); (2) the protection and socialization of offspring by adult females; and (3) the modification of adolescent male aggressive expression by the selective interference of adult males. As a consequence of adult response to the agonistic behavior of adolescent males, maturing males (1) selectively target other older males, avoid aggression against females and immatures; (2) form alliances with other males; and (3) become progressively isolated from their matrilines.     

Dominance style of female white‐faced capuchins

Dominance style, the level of tolerance displayed by dominant individuals toward subordinate ones, is exhibited along a continuum from despotic to relaxed. It is a useful concept to describe the nature of dominance relationships in macaque species and it bridges among multiple features of dominance hierarchies, aggression, kinship and conflict resolution. Capuchins share many behavioral similarities with Old World monkeys and like macaques, may exhibit a suite of covarying characteristics related to dominance. Here, we provide an assessment of dominance style by examining measures of aggression and kin bias in 22 adult female white‐faced capuchin monkeys (Cebus capucinus) in three social groups at Santa Rosa Sector, Costa Rica. We found that bidirectionality of aggression was low (mean = 6.9% ± SE 1.6). However, there were few significant correlations between kin relatedness and social behavior (approaching, grooming, proximity, and co‐feeding), even though the intensity of kin bias in grooming was moderate and higher in the larger group. We conclude that patterns of aggression and kin‐biased behavior in our study animals are dissimilar to the patterns of covariation observed in macaque species. While unidirectional aggression suggests a despotic dominance style, the moderate expression of kin bias suggests an intermediate to relaxed classification when compared with results from an analysis of 19 macaque species. Additional studies of capuchin species and behaviors associated with dominance style (i.e., conciliatory tendencies) would help to create a comparative framework for the genus Cebus, and allow for more detailed cross‐species comparison of dominance relationships across all primates. Am J Phys Anthropol 150:591–601, 2013. © 2013 Wiley Periodicals, Inc.     

Testosterone, paternal behavior, and aggression in the monogamous California mouse (Peromyscus californicus)

Testosterone (T) mediates a trade-off, or negative correlation, between paternal behavior and aggression in several seasonally breeding avian species. However, the presence or absence of a T-mediated trade-off in mammals has received less attention. We examined the relationship between paternal behavior and territorial aggression in the biparental California mouse, Peromyscus californicus. In contrast to seasonally breeding birds, T maintains paternal behavior in this year-round territorial species. Castration reduced paternal behavior, whereas T replacement maintained high levels of paternal behavior. We hypothesize that T is aromatized in the brain to estradiol, which in turn stimulates paternal behavior. In contrast to paternal behavior, aggressive behavior was not reduced by castration. Interestingly, only sham males showed an increase in aggression across three aggression tests, while no change was detected in castrated or T-replacement males. Overall, trade-offs between aggression and paternal behavior do not appear to occur in this species. Measures of paternal behavior and aggression in a correlational experiment were actually positively correlated. Our data suggest that it may be worth reexamining the role that T plays in regulating mammalian paternal behavior.     

A head above the rest: Height and adolescent psychological well-being

Using data from the National Longitudinal Study of Adolescent Health, we examine the effect of adolescent height on mental health as measured by Center for Epidemiological Studies Depression (CES-D) scores and Rosenberg Self-Esteem (RSE) scores. We find evidence that height is associated with fewer symptoms of depression among females 17–19 years of age, and among males 12–19 years of age. The negative relationship between height and depression among males persists after controlling for body mass index (BMI), differences in pubertal timing, and individual fixed effects, but does not explain the effect of height on educational attainment. We conclude that there is a small psychological benefit for males to being taller as an adolescent.