If I need you to make me happy, I've got to use you, I've got to manipulate you, I've got to find ways and means of winning you. I cannot let you be free.

Panksepp finds a neural corollary between the dynamics of opiate addiction and our dependence on the people for whom we feel our strongest attachments. All positive interactions with people, he proposes, owe part of their pleasure to the opioid system, the very circuitry that links with heroin and other addictive substances.

Panksepp theorizes that the gratification that addicts get from their drugs biologically mimics the natural pleasure we get from feeling connected to those we love; the neural circuitry for both are largely shared. Even animals, he finds, prefer to spend time with those in whose presence they have secreted oxytocin and natural opioids, which induce a relaxed serenity - suggesting that these brain chemicals cement our family ties and friendships as well as our love relationships.