In his song “Cautious Man,” Bruce Springsteen sings about a man who’d “on his right hand . . . tattooed the word ‘love’ and on his left hand was the word ‘fear.'” Turns out that Bruce was onto something. Fear and love are indeed two sides of the same thing—or, if you want to be all scientific about it, they’re governed by the same hormone, oxytocin.
Mostly oxytocin’s been associated with love. You make out with somebody, your body sends a huge shot of it to your brain and, all of a sudden, you want to move in together and start making babies (or at least doing the sorts of activities that result in babies). Or, once you go through labor and childbirth, your body’s oxytocin-manufacturing mechanism goes into overdrive to make sure you’ll love and cherish your baby instead of wanting to throw it out the window as revenge for all the agony it caused you.
Dr. Jelena Radulovic, a professor of psychiatry and pharmacology at Northwestern’s Feinberg School of Medicine, believed this, too, when she set up an experiment on mice to test how the body reacted to different hormones during social interactions. She hypothesized that mice that produced more oxytocin would feel more positive effects from social interaction while those that produced more glutamate would have more negative feelings. It turned out that that oxytocin caused the mice to act more fearful.
That was 25 years ago. She’s been studying oxytocin and fear ever since.