Blame your brain the next time you fall in love, or experience lust, or settle into long-term contentment. And yes, it can all happen at once.
By COLETTE BANCROFT
Published February 13, 2004
Romantic love really is all about chemistry, and on a brain scan it looks a lot like addiction. Evolution has hard-wired us to form long-term attachments - and to fool around. And those antidepressants that helped you get over your last romance might keep you from finding a new one.
That's just some of the news in Why We Love: The Nature and Chemistry of Romantic Love (Henry Holt & Co., $25) by Helen Fisher, an anthropologist and research professor at Rutgers University. Its pages are laced with poetry and romantic legends, but the book focuses on Fisher's scientific research into love.
Speaking from her home in New York City, Fisher says, "The human brain evolved about 2-million years ago, and I think romantic love really took off at that time."
Her studies of the evolution of sex, love, marriage and gender differences in the brain and behavior have been the source of four books. As part of her research for Why We Love, she took a look inside the brains of 20 people who identified themselves as "madly in love."
The subjects were placed in a functional magnetic resonance imaging machine, which takes pictures of blood flow to active parts of the brain. They alternately gazed at a photograph of their beloved, performed a simple math exercise and looked at a neutral photo of an acquaintance.
When Fisher and her colleagues analyzed the data, they found that certain parts of the brain's "reward circuitry" lit up like fireworks when subjects were looking at their honeys. That indicated the brain was revving up its production of powerful chemicals associated with concentration, energy and elation.
"That really blew my mind," Fisher says. "Originally I thought romantic love was an emotion, or a constellation of emotions. But when we saw what was going on in the brain, I realized it was a drive," like hunger, thirst, the maternal instinct or the sex drive.
Love at first sight is straight out of nature, Fisher says, a descendant of animal attraction.
"A squirrel has to choose another squirrel. If he finds one with a bushy tail and nice whiskers, he has to make a move. He can't spend a year talking to her about T.S. Eliot."
Although few species of animals form lasting pair bonds, many of them do make choices. "There's not a mammal on this planet who will copulate with just anybody. They all have favorites."
For humans, Fisher says, choosing favorites has evolved into a much more elaborate system of responses. We have three distinct mating drives, each with its own neurochemicals.
Lust, the craving for sexual gratification, is associated with testosterone in both sexes. Intense romantic love that idealizes a particular partner is tied to dopamine and norepinephrine, while attachment, a calm, secure union with a long-term partner, is related to the hormones oxytocin and vasopressin.
"Those three different brain systems act independently," Fisher says. "We've really inherited a very difficult design."
We expect lust to lead to romantic love and then to attachment, but they can happen in any order, Fisher says. We can even feel them for different people at the same time.
Our culture tends to put such a high value on romantic love that many people feel the attachment stage is the failure of love.
"Americans don't respect attachment. It's a very ornate and remarkable feeling. It's much more subtle, much more complex. Romantic love is just like being hit by a truck," she says.
Attachment occurs in all human cultures. And so does adultery. "I think we're wired for both.
"Ninety-seven percent of mammals do not form pair bonds to raise their young. Adultery is not the news. The news is that we bother to pair up at all."
Fisher says that both attachment and wanderlust were adaptive behaviors. The first human mothers had to carry their infants in their arms instead of on their backs like other primates, so they needed mates to help them survive.
On the open, predator-haunted plains on which early humans lived, one man couldn't effectively protect a whole harem of women and their children, but he could protect one family. So individuals who formed pair bonds were more likely to raise their young and pass on the brain circuits for attachment.
"Now, 2-million years ago, it was also adaptive for that male to slip over the hill and copulate with another woman," Fisher says. "If he fathered children with her, it doubled the number of his genes that got passed along."
Adultery was adaptive for women because it could mean extra protection and resources for their children. If a woman got pregnant by more than one man, it meant she had children with more genetic variation. And they passed on the tendency for adultery over the millennia.
Fisher says, "We've evolved a dual reproductive strategy: the tendency to pair up and the tendency for the roving eye. We're in a pickle."
Complicating matters is the intensity of romantic love, which Fisher says is as powerful as addiction to drugs - and triggers similar pleasurable neurochemicals.
"All the addictions are associated with dopamine: cocaine, heroin, alcohol, tobacco."
Your brain in love is responding to that chemistry. Fisher says romantic love has three main characteristics of addiction. "First is tolerance. First you just see the guy on Saturday. Then you see him on Saturday and Wednesday. And pretty soon you want to move in. You need more and more.
"Then there's withdrawal. If you're without this person you go through this horrible pain.
"And finally there's relapse. You think you're over it, and eight months later he calls to ask you something and you're right back in love with him."
We've adapted to getting our hearts broken, too. Fisher says rejected lovers go through a stage of protest, followed by one of resignation and despair.
When the reward of romantic love is taken away, the brain's reward system first becomes elevated, and motivation and obsession increase, according to Fisher's research. That leads to an intense effort to win back the lost love.
"It's a typical mammalian response, to win back the mother," she says. "If you put a puppy in the kitchen by itself, away from its mother, it will throw it itself at the door and whine and cry."
So spurned lovers beg for another chance and often get it. "Protest is adaptive if it works, if you can win back that mating partner."
But the protest stage can also involve enormous rage, even violence. Anger can be adaptive, Fisher says. "For millions of years, it was, you've got to get on with the mating process, move on to the next potential mate. So that fury would alienate them, and it would also help you to detach from them."
Just as protest may win love back and rage may help sever the connection, depression might be adaptive too.
"Depression evolved for a lot of good reasons. It's an accurate, honest sign that things are really wrong. It signals that to your friends, your family, the people around you, so they're more likely to come around and help you.
"And depression gives you a real dose of reality. You're no longer looking through those rose-colored glasses. And, of course, you can learn something from the experience."
In the last couple of decades, science has plumbed the chemistry of depression and invented ways to treat it. One class of antidepressants, selective serotonin re-uptake inhibitors (such as Prozac and Zoloft), have become enormously popular.
Fisher says that although in the short term they can be lifesavers, the drugs may have an unanticipated effect - they could be a sort of antidote to love.
When we fall in love, dopamine and norepinephrine levels rise, and serotonin levels fall. Taking SSRIs brings up the serotonin level and suppresses dopamine. That could inhibit romantic love.
Fisher says, "Long-term use could jeopardize people's ability to fall in love, to stay in love, or even to feel attachment for the partner they've got."
Research into the chemistry of love raises the question of whether it could lead to similar enhancers, the long-sought love potion.
Fisher says romantic love is too complicated for chemical manipulation.
"You can take cocaine right now, you can take Wellbutrin right now, and elevate your dopamine. But you won't fall in love with the next person you see.
"There are just so many cultural factors."
But, she says, such research may have indirect effects. For example, one thing that triggers dopamine is a novel experience, anything from an exotic vacation to bungee jumping. That could point to a way to keep a spark of romance in a long-term attachment.
"If you understand this, you can do novel things with someone you love. It may enable us to trigger these brain systems in our own ways," Fisher says.
"Now, you'll never get back that crazy feeling, that intensity and obsession all the time. And that's good, because it's very metabolically expensive.
