A bore in the head:

> in an artificially monogamous couple
Monogamy is natural. Wild people are able to survive only in a cohesive family and family group, and to raise offspring - only in a strong pair. Children are growing up very long, all this time they need to be protected and fed. (First of all, the mother feeds ALL: the collection is more reliable and stable. Fathers mainly drive away predators and rivals, and with the prey as lucky.) Human biology has been greatly affected by monogamy: it is both hidden ovulation (so that foreign males notice it less), and continuous fertility, and a decrease in the size of the jaw (DIMINATION of intra-species aggression, including. Fighting for females and food, in these matters cooperation is more important to the species than fellowship, and the small size of the semen (no alpha males in humans).

> here is the wrong link links
Oxytocin is involved in all long-term attachments (from infant and parental to sexual and friendly neighborhood). He is stimulated at least by sex, at least by lactation, at least simply by communicating with "his own". It stimulates pro-social behavior in the group and hostility toward strangers. So, parental care for loved ones is not a female function and not a mistake of nature, but the norm for humans. It’s not we’re too good, it’s your affection disorder.