A handful of young people who had just fallen madly in love volunteered to have their brains scanned to see what areas were active when they looked at a picture of their sweetheart. The brain areas that lit up were precisely those known to be rich in a powerful feel good chemical, dopamine – the substance that brain cells release in response to cocaine and nicotine.
Dopamine is the key chemical in the brain’s reward system, a network of cells associated with pleasure – and addiction.
In the same lab, older volunteers who claimed to still be intensely in love after two decades of marriage participated in the same experiment. The same brain areas lit up, showing that, at least in some lucky couples, that honeymoon feeling can last.
But in these folks, other areas lit up, too – those rich in oxytocin, the cuddling chemical that helps new mothers make milk and bond with their babies, is secreted by both sexes during orgasm, and that, in animals, has been linked to monogamy and long-term attachment.