The hypothalamic-pituitary-gonadal axis: a switch-controlled, condition-sensitive system in the regulation of life...

This article is part of a Special Issue "Puberty and Adolescence". Life history theory provides an overarching framework for explaining the development of individual differences in reproductive strategies and highlights the role of familial and ecological conditions in regulating pubertal timing. Parental investment and sexual selection models afford a powerful framework for explaining the emergence of sex differences in reproductive strategies and suggest that pubertal timing in males and females is differentially sensitive to psychosocial stress. The West-Eberhard's (2003) model of switch-controlled modular systems provides the foundation for a comprehensive analysis of variation in reproductive strategies at the level of mechanism and development. Applied to puberty, this model provides a framework for explaining how genes and environments interact over development, are modulated by extant phenotypic characteristics, and operate through control of regulatory switch mechanisms across multiple levels of the hypothalamic-pituitary-gonadal axis. Taken together, life history theory, parental investment and sexual selection models, and the West-Eberhard framework enable an integrated evolutionary-developmental analysis of between-sex variation and within-sex variation in pubertal processes and their role in regulating alternative life history strategies.