User:Jackiechanyt/sandbox

Specific examples
Early pubertal timing - precocious puberty - is associated with negative outcomes in both genders. Early maturing girls have been found to be at risk for teenage pregnancy, drinking and weight problems , and giving birth to low birth weight infants. Early maturing boys are at risk for sexual promiscuity and delinquency and testicular and prostate cancer. Individual difference in pubertal timing may be influenced by weight, physical activity and genetics.

Menarche
A central event of female puberty – menarche – is associated with father absence. According to the evolutionary explanation, an unstable home environment (e.g. father absence) discourages a long-term mating life history, leading girls to adopt a short-term reproductive strategy, such as early menarche. This is because they perceive resources they have as scarce and, possibly, their lifespan to be shorter, under the influence of father absence. An early menarche can increase the chance of fertility, while other short-term reproductive strategies can diversify the genes inherited in offspring. These could lift up a higher success rate of rearing children to adolescence.The stress of father absence also prompts girls to develop a variety of internalising disorders, such as bulimia and depression. They may lower the person’s metabolism, causing an excessive weight gain which precipitates early menarche. A study shows that there are fewer monitored meals in the father-absent household. Having meals in the family is arguably more beneficial to children than is eating alone (i.e. solitary eating), as the former lowers the chance of obesity.

However, it has been disputed whether the environmental stress of father absence stimulates weight gain, and thus accelerates early puberty. Likewise, the stress arisen from the absence of mother has been shown to have little influence on the child’s body weight. Since mother absence does not predict weight gain in children, it seems that the increase in the child’s body weight observed is due to the isolated genetic influence of an absent father, rather than the global environmental stress cause by the absence of either parent This is possibly because in ancestral times the survival rate of children with mother being absent was extremely low. A specialised mechanism to deal with mother absence has never been developed.

In addition, recent findings seem to regard genes, rather than the environment, as the mechanism underlying the positive correlation between high body mass index and earlier first menarche onset. Androgen receptor gene may predispose a father to impulsive and externalising behaviours (e.g. family abandonment) and his offspring to early puberty. The essentialness of androgen receptor to female fertility and ovary development has been proven by rodent studies.

Sexual behaviour
Father absence in a household can result in children (of both sexes) having earlier average ages of first sexual intercourse than those raised in father present households. There is also the effect of increased rates of teenage pregnancy. Some evolutionary theories propose that early childhood is vital for encoding information that shapes future reproductive strategies (Belsky, 2007) in regulating physical and motivational pathways of sexual behaviour. Conflicting and stressful parental relationships can lead children to believe that resources are limited, people are untrustworthy, and relationships are opportunistic. As they replicate their parents’ mating-oriented reproductive behaviour, they tend to have multiple sexual partners and erratic relationships. Children implicitly and explicitly model their sexual attitudes and behaviours on their parents, see engagement in non-marital sex as normative. Father absence however can be a byproduct of initial social and economic strain within the household (e.g. violence, lack of educational opportunities and cumulative life exposure to poverty can increase the likelihood of early sexual endeavours and pregnancy). The timing of first intercourse can be heritable - shorter alleles of the X-linked androgen receptor (AR) gene has been associated with aggression, impulsivity, high number of sexual partners, divorce in males and earlier ages of physical maturation in females