According to life-history theory, any organism will strategically divide resources toward growth, maintenance and reproduction (Ellis, 2004). In a harsh environment, humans might mature earlier to enable earlier reproduction – to secure the transmission of one’s own genes in the next generations (Belsky et al., 1991). Previous research has indeed indicated that harsh family environments, such as chaotic life environments or rejecting, inconsistent parental behavior, and severe stressors can lead to earlier pubertal maturation (in girls) (Belsky et al., 2010; Belsky, Steinberg, et al., 2007; Ellis et al., 1999; Holdsworth & Appleton, 2020; Sheppard et al., 2016). Recently, a two-hit model of accelerated aging has been proposed (Belsky & Shalev 2016), specifying that early adversity does not necessarily lead to earlier sexual reproduction even though it has been found to predict pubertal maturation. Belsky and Shalev hypothesized that a supportive environment during puberty can act as a buffer against early sexual reproduction. Moreover, they hypothesized a potential biological mechanism, wherein early childhood adversity may result in epigenetic changes (i.e. advanced biological age compared to chronological age measured via epigenetic clocks) which might result in earlier pubertal maturation and (in case of a non-supportive environment) in earlier sexual reproduction.
Some previous proposals have looked at parts of this model (e.g. B878, B897, B2760, B2883, B3077, B3690), but we will be the first to combine these parts, such as relation between father absence and puberty or the relation between pubertal development and sexual risky behaviors into one overarching model of the life history theory.