These mechanisms include an intricate and intensively studied system of relationships involving stress- and socialization-related hormones (including cortisol, oxytocin and vasopressin), behavior and affect, and neurotransmission during maturation and adolescence (Cameron, 2004; Insel, 2003; Light et al., 2004; Walker et al., 2004), manifesting sex dimorphism in many of its components. Belsky et al. (1991), based on evolutionary considerations, hypothesized that the child's perceived lack of resources will lead to the development of “behavior patterns that function to reduce the age of biological maturation” (p. 650), whereas the opposite effect will result from the availability of resources. This theory does not exclude the possibility of an alternative, genetic, explanation of variation in developmental timing. Although the data confirm the relationship between parental absence and a lower age of menarche (Moffitt et al., 1992), it is not certain that it is due to resource-related stress, and the presence of the mother's new partner may be of greater relevance than the father's absence (Ellis and Garber, 2000). Early maturation in girls and boys has been shown to be associated with delinquency, mediated by
