One theory about the origins of romantic love (other than the evolutionary mandate to continue the species) says it emerged about 5 million years ago when our ancestors developed specialized hormones and neurotransmitters that enhanced cognition and altered our emotions.

But what exactly is getting stimulated in your brain when you fall in love, filling you with delight and joy?

A recent study out of Australia explains that the hormone oxytocin — the bonding hormone — lays the foundation. It's made in the hypothalamus and released into the bloodstream by the pituitary gland. Touch, gaze, and even sound can stimulate its production.

In women, oxytocin affects organs such as the uterus and tissue in the breast, and impacts childbirth and lactation.

In men, it's thought to influence libido and orgasm. In both sexes, it acts as a chemical messenger in the brain, influencing behavior.

But it is the addition of large amounts of the hormone/neurotransmitter dopamine, stimulated by doing something pleasurable, that the researchers found creates the euphoric feeling of being in love.

And that's not all this two-hormone stew can do for you. Oxytocin helps cultivate the generosity and empathy that are important for emotional and cognitive development, and dopamine strengthens motivation and focus.

This Valentine's Day when you and your sweetheart share a moment of bliss, give thanks for the intense emotional hug that being in love provides — and that it enhances your ability to navigate through sometimes less-than-loving challenges in the world at large.