Effects of the social environment during adolescence on the development of social behaviour, hormones and morphology in male zebra finches (Taeniopygia guttata)

Abstract Background Individual differences in behaviour are widespread in the animal kingdom and often influenced by the size or composition of the social group during early development. In many vertebrates the effects of social interactions early in life on adult behaviour are mediated by changes in maturation and physiology. Specifically, increases in androgens and glucocorticoids in response to social stimulation seem to play a prominent role in shaping behaviour during development. In addition to the prenatal and early postnatal phase, adolescence has more recently been identified as an important period during which adult behaviour and physiology are shaped by the social environment, which so far has been studied mostly in mammals. We raised zebra finches ( Taeniopygia guttata ) under three environmental conditions differing in social complexity during adolescence\ua0-\ua0juvenile pairs, juvenile groups, and mixed-age groups - and studied males\u2019 behavioural, endocrine, and morphological maturation, and later their adult behaviour. Results As expected, group-housed males exhibited higher frequencies of social interactions. Group housing also enhanced song during adolescence, plumage development, and the frequency and intensity of adult courtship and aggression. Some traits, however, were affected more in juvenile groups and others in mixed-age groups. Furthermore, a testosterone peak during late adolescence was suppressed in groups with adults. In contrast, corticosterone concentrations did not differ between rearing environments. Unexpectedly, adult courtship in a test situation was lowest in pair-reared males and aggression depended upon the treatment of the opponent with highest rates shown by group-reared males towards pair-reared males. This contrasts with previous findings, possibly due to differences in photoperiod and the acoustic environment. Conclusion Our results support the idea that effects of the adolescent social environment on adult behaviour in vertebrates are mediated by changes in social interactions affecting behavioural and morphological maturation. We found no evidence that long-lasting differences in behaviour reflect testosterone or corticosterone levels during adolescence, although differences between juvenile and mixed-age groups suggest that testosterone and song behaviour during late adolescence may be associated

Reliability of pubertal self-assessment in Hong Kong Chinese children

Aim: To validate a Tanner stages self-assessment questionnaire using gender-specific line drawings and brief explanatory text in Chinese. Methods: Design: A cross sectional study design. Setting: One primary and two secondary schools. Participants: 172 boys and 182 girls aged between 8 and 18 years. Main outcome measures: Students' self-assessments of pubertal maturation were compared with assessments made by a same gender rater using visual depiction physical examination. Raters' physical examinations were performed after the children had answered the self-assessment questionnaire individually and in private. Raters were blinded to the self-assessment results. Accuracy rates and weighted kappa statistic were used to evaluate the degree of agreement between children and raters. Results: Substantial to almost perfect agreement was found between self- and rater's assessments of breast development and pubic hair growth in girls [weighted kappa 0.72 (P < 0.0001, 95% CI 0.66, 0.79) and 0.83 (P < 0.0001, 95% CI 0.78, 0.87) respectively]. Moderate to substantial agreement was found between self- and rater's assessments of male genital development and pubic hair growth [weighted kappa 0.58 (P < 0.0001, 95% CI 0.48, 0.68) and 0.80 (P < 0.0001, 95% CI 0.74, 0.86) respectively]. Most agreements between self- and rater's assessments differed by only one Tanner stage. Agreement was higher for girls than boys. Girls tended to overestimate their breast stages and boys tended to underestimate their genitalia development. Conclusion: This study confirms that a Tanner pubertal self-assessment questionnaire with line drawings and explanatory Chinese text can reliably estimate sexual maturation status in Hong Kong Chinese children. © 2008 The Authors.link_to_subscribed_fulltex

Weak associations between pubertal development and psychiatric and behavioral problems

Pubertal development has been associated with adverse outcomes throughout adolescence and adulthood. However, much of the previous literature has categorized outcome variables and pubertal timing measures for ease of mean difference or odds ratio interpretation. We use a UK-representative sample of over 5000 individuals drawn from the Twins Early Development Study to extend this literature by adopting an individual differences approach and emphasizing effect sizes. We investigate a variety of psychiatric and behavioral measures collected longitudinally at ages 11, 14 and 16, for multiple raters and for males and females separately. In addition, we use two measures of pubertal development: the Pubertal Development Scale at each age, as well as the age of menarche for girls. We found that pubertal development, however assessed, was linearly associated with a range of psychiatric and behavioral outcomes; however, the effect sizes of these associations were modest for both males and females with most correlations between −0.10 and 0.10. Our systematic analysis of associations between pubertal development, and psychiatric and behavioral problems is the most comprehensive to date. The results showing linearity of the effects of pubertal development support an individual differences approach, treating both pubertal development and associated outcomes as continuous rather than categorical variables. We conclude that pubertal development explains little variance in psychiatric and behavioral outcomes (&lt;1% on average). The small effect sizes indicate that the associations are weak and should not warrant major concern at least in non-clinical populations