Juvenility, Puberty and Adolescence Among Bangladeshi and British Youth

Abstract

The ABBY (Adolescence among Bangladeshi and British Youth) Project explores the relationship between migration and growing up from a biocultural perspective. Based on evolutionary hypotheses, it tests for facultative adaptation to different developmental environments during the transition from child to adolescent using contrasting conditions within ethnicity, ecology, and migration. I explore the relationship between these variables and the timing and tempo of adrenarche, thelarche, pubarche and menarche through comparisons of biological and cultural markers of development among 488 girls, aged 5–16, belonging to the following groups: Sylheti, first generation British-Bangladeshi, second generation British-Bangladeshi and white British. This project supports evidence that the timing, tempo and experience of juvenile and pubertal development vary across populations with possible lasting implications for the strategic allocation of reproductive effort. Specifically, adrenarche occurred two years earlier in first generation migrant girls to Britain, suggesting that change in ecological factors results in more rapid juvenile onset. Thelarche occurred earlier with increasing individual and ancestral generations lived in the UK, suggesting that local ecological factors result in earlier pubertal onset. Contrary to predictions, menarcheal timing and oestrogen levels did not differ significantly among groups. Acculturation did not account for differences in behaviours during juvenile and pubertal development between groups. Instead, the stages of practising to being dedicated to hijab (which occur during juvenility and after puberty, respectively) better reflect the social process of growing-up as Bangladeshi girls in East London. Growing up here may be uniquely stressful among first generation migrants. Psychosocial stress may interact with other ecological factors resulting in an overall slower tempo of juvenile development. The extended period of plasticity during juvenility among girls who experienced a change in socio-ecological factors may be an adaptive response to ensure a better tracking of current socio-ecological conditions and also a better prediction of later ones.