It may seem almost unbelievable, but a single hormone called oxytocin is responsible for life's most fulfilling emotions: love, trust and commitment.

Oxytocin is a neuropeptide that helps regulate many of the body's functions, including hunger, thirst and blood pressure. But it plays a special role in bonding with other people. When we're touched by someone we trust, when we make love and orgasm, when we simply spend time with someone we like, our brains release pulses of oxytocin that make us feel deep bonds with that person.

But we're not born with this response. Our newborn bodies enter the world knowing how to breathe, how to digest food, how to pump blood. But they don't know how to love.

The most profound human experience there is must be learned after we're born.

The brain begins to learn the oxytocin response during labor, when oxytocin stimulates the mother's uterus to contract. At the same time, it floods mother's and baby's bloodstreams, priming their bodies for their first experience of connection.

If the baby is breastfed, the same oxytocin that lets down the milk increases the feelings of safety, trust and love. Every time the baby is touched, held and nursed by its mother -- or another primary caregiver -- its brain learns to release its own oxytocin pulses, soothing the system and deepening the love.

But many things can interfere with the development of the oxytocin response. If the nursing mother is anxious, angry or afraid, her brain will release fight-or-flight neurochemicals, teaching her baby's body that being close to someone is frightening. Abuse, harshness, neglect and indifference all take their toll on the brain's ability to release oxytocin.

When we grow up without learning the oxytocin response, we can't truly bond with others. Other people are speaking a secret chemical language that we can't hear. Our relationships may get stuck at romance and sex, then fall apart when the excitement dwindles. Friendships may be filled with hurt feelings and anger. We can only feel bonded with people who hurt us or reject us. We wander through life feeling deeply alone. Our "hearts" -- the body's loving responses -- are truly broken.

But there's one more amazing thing to know about the oxytocin response: Our brains can learn it at any age. It's never too late to heal these broken hearts.

The Chemistry of Connection: How the Oxytocin Response Can Help You FInd Trust, Intimacy and Love, to be published by New Harbinger in spring 2009, will show you how to birth and nurture your children and heal yourself, so you can give and get the love you need.

Read all about oxytocin in my blog, Hug the Monkey.

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