Helen Fisher in Nautilus (scene from Before Sunrise):
One-night stands; hooking-up; friends with benefits; living together; pre-nups; civil unions. These all spell caution. But they also spell logic—because our brain is soft-wired to attach slowly to a partner.
The basic circuits for romantic love lie in primitive regions of the brain, near those that orchestrate thirst and hunger. Romantic love is a drive—one of three basic brain systems that evolved to direct our fundamental human mating and breeding strategy. The sex drive predisposes you to seek a range of mating partners; romantic love enables you to focus your mating energy on a single individual at a time; and feelings of attachment incline you to form a pair-bond at least through the infancy of a single child. Feelings of romantic love and deep attachment to a partner emerge in a pattern highly compatible with the spirit of the times—that is, with slow love.
I say this because my colleagues Lucy Brown, Art Aron, Bianca Acevedo, and I have put new lovers into a brain scanner (using functional Magnetic Resonance Imaging, or fMRI) to measure neural activity as these men and women gazed at a photo of their sweetheart. Those who had fallen madly in love within the past eight months showed activity in brain regions associated with energy, focus, motivation, craving, and intense romantic love. But those who had been passionately in love for eight to 17 months also showed activity in an additional brain region associated with feelings of attachment.
Romantic love is like a sleeping cat; it can be awakened at any time. Feelings of deep attachment, however, take time, and they can endure. In another of our studies, led by Acevedo, we put 17 men and women in their 50s and early 60s into the brain scanner. These participants had been married an average of 21 years, and all maintained that they were still madly in love with their spouse. Their brains showed that they were: They were deeply attached as well.
We have even begun to map some of the brain circuitry responsible for this marital happiness. In our study of long-term lovers, those who scored higher on a marital satisfaction questionnaire showed more activity in a brain region linked with empathy, a trait they had most likely retained from their initial passion. Moreover, when psychologist Mona Xu and her team used my original research design to collect similar brain data on 18 young men and women in China, she found that those who were in love long term showed activity in a brain region associated with the ability to suspend negative judgment and over-evaluate a partner, what psychologists call “positive illusions.” Much like men and women who have just fallen madly in love, these long-term partners still swept aside what they didn’t like about their mate and focused on what they adored.
Because feelings of attachment emerge with time, slow love is natural. In fact, rapidly committing to a new partner before the liquor of attachment has emerged may be more risky to long-term happiness than first getting to know a partner via casual sex, friends with benefits and living together. Sexual liberalism has aligned our courtship tactics with our primordial brain circuits for slow love.
More here.