These are genetic vehicles for parents to succeed generations

This hormone plays a key role in male mating effort

These types of siblings have 50% the same genes

this hypothesis partly accounts for more female parental investment: a male is unsure whether the offspring is his or not

Testosterone is linked to allocating time and energy to seeking and competing for mates

This is a by product of increased life expectancy

in fairytales and traditional folklore they often get depicted as evil villains 

During a study men’s skin conductance increased significantly more when conversing with the attractive woman than the less attractive woman, suggesting that they were more physiologically aroused, or nervous with 

The type of grandparent is likely to invest more in their grandchildren

this is referred to as higher occurrence of child abuse and family violence by stepparents than by genetic parents

Key components of human parental investment occurring internally in women

This is rare in the animal kingdom and is only found in 3% of mammals

there are evolved mechanisms (especially in women) that increase the prospects of their childrens survival

The effects of the premium men place on physical appearance may lead to negative or maladaptive outcomes for women—eating disorders 

Children who grow up without this have higher cortisol levels and are more stressed