Will you marry me?
It's a simple question made difficult because a lifetime of commitment rides on the answer. And how we arrive at this sought-after moment is one of the most complicated mysteries of our lives. How do we find love? Or more important, what exactly is love? Why do we feel it for one person and not another?
Biological anthropologist Helen Fisher has devoted a lifetime of research to these questions, and now she believes she has found some of the answers.
"I feel as if I've stumbled into Mother Nature's kitchen and found some of her recipes," Fisher said.
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A seminal moment in Fisher's research occurred when she and her colleagues, Arthur Aron and Lucy Brown, started putting young lovers in an MRI machine. When they showed these subjects photos of their partners, a small region of the brain called the ventral tegmental area lit up on the scan. The ventral tegmental area produces the stimulant dopamine, and sends it to the brain's reward centers -- the centers for wanting, craving, motivation, focused attention and ecstasy.
For Fisher, it was a revelation.
"This made me realize that romantic love is not an emotion. ... It's a basic mating drive. A motivation system. A system to try to win life's greatest prize, which is the right mating partner," she said.
But while Fisher thought she knew what love was, it took a call from an Internet dating service to get her thinking about why we fall in love.
"They asked me a question: Why do you fall in love with one person rather than another? And I said, 'I don't know. Nobody knows.'"
Fisher found the question intriguing, and she began to suspect that the answer must lie somewhere in the brain.
"What I had to do," she said, "is figure out if there was any biology to your behavior."
Fisher began an exhaustive review of the scientific literature, looking, for example, at studies that have associated specific genes with certain behavior patterns, at studies that have examined the impact of recreational drugs on the brain and at studies that have examined the change in personality brought about by drugs like L-Dopa, which drives up dopamine and is given to people with Parkinson's Disease.
In the end, Fisher came to believe that there were four broad biological personality types associated with four specific neurotransmitters and hormones: dopamine, serotonin, testosterone and estrogen.
Fisher believes we are all some combination of these four types, which she has named the explorer (dopamine), the builder (serotonin), the director (testosterone) and the negotiator (estrogen).
Good examples of the risk-taking explorers, Fisher said, would be John F. Kennedy, Ernest Hemingway and Angelina Jolie. Colin Powell, she said, exemplifies the calm, traditional builder. Directors are analytical, tough-minded and decisive, and Fisher believes Bill Gates is a perfect example. Negotiators, on the other hand, are emotionally expressive and empathetic. A good example? Bill Clinton. "He says, 'I feel your pain,'" Fisher laughed.