"What 'Tis to Love?"*

Evolution has bequeathed us three different brain systems for love.

Posted Aug 27, 2009

Hello all; it's a privilege to join you. As my first blog, with the overarching title of OF HUMAN BONDING, I would like to set my foundation with something I have been saying for some time. I believe that humanity has evolved three distinct yet inter-related brain systems for mating and reproduction: the sex drive; romantic love; and deep feelings of attachment for a long term partner.

The sex drive (associated primarily with the testosterone system in both men and women) developed foremost to motivate us to seek sex with a range of partners. Romantic love (associated primarily with the dopamine system) evolved to enable us to focus our time and metabolic energy on just one individual at a time. And the attachment system (primarily associated with the oxytocin and vasopressin systems) emerged to motivate us to sustain a pair-bond long enough to rear at least one child through infancy as a team.

These three brain systems have many complex interactions. Among them, sexual stimulation of the genitals triggers dopamine release and can push one over the threshold toward falling in love; and with orgasm the release of oxytocin and vasopressin can stimulate feelings of attachment (which is why casual sex is rarely casual; it either turns you on or off.)

Nevertheless these brain systems are not always well connected; indeed, they can operate independently. Hence you can feel deep attachment to one partner, while you feel intense romantic love for someone else, while you feel lust for a host of others. This brain circuitry spells both opportunity and trouble. And although we have evolved a huge cerebral cortex with which we often make decisions about our mating and reproductive lives, many other forces contribute to how we express these basic mating drives. In this blog, I hope to talk about all the myriad ways that cultures and individuals-both in the past and present- express these neural systems to produce our myriad patterns of human bonding.