Why people love has been the subject of songs and movies. It has been captured in the pages of fairy tales and novels. Most of it has been speculation or creative storytelling at best.
More recently, scientists and researchers have been studying the topic, says Helen Fisher, research professor in the department of anthropology at Rutgers University in New Brunswick, N.J. She holds a doctorate in biological anthropology.
"I am studying 2 million people on the dating site Chemistry.com," Ms. Fisher says. "I see who some of them think would be attractive to go out with. In the future, I would like to see who marries who."
On July 18, Smithsonian Associates is holding a seminar featuring Ms. Fisher, called "Falling in Love: Why You, Why Me?" The event takes place at 6:45 p.m. at the S. Dillon Ripley Center in Southwest.
There are many ways to look at love, says Lourdes Griffin, executive director for behavioral health services at Washington Hospital Center in Northwest. She holds a doctorate in psychology.
"When we say falling in love, it's a term we use in Western society rather than Eastern society," Ms. Griffin says. "You've moved from neutral to feeling more positive. You've now begun to have attractions."
Ms. Fisher says she has designated four broad categories for people when studying their attractions. She classifies people depending on what chemical activity most frequently occurs in their brains. People can determine their classification by taking an online test.
For instance, the "explorer" appears to express a lot of activity in the dopamine system of the brain. Explorers generally are risk-taking, spontaneous, impulsive, creative, energetic and curious.
"Builders," who have an active serotonin system, usually are calm, social and popular. They tend to be interested in people and have networks of friends and relatives. They are conscientious and loyal; they tolerate boredom and like schedules and plans. They are quite literal and conventional, she says.
"Negotiators," both men and women, have high activity in the estrogen system. They are verbal and good at reading postures, gestures and tone of voice. They have good people skills, are sympathetic, compassionate, nurturing, imaginative and idealistic, she says.
"Directors" have a lot of activity in the testosterone system, she says. They are direct, decisive and good with rule-based systems. They generally are good composers and engineers. They are competitive and aggressive and like to debate.
What causes attraction among people is a topic Ms. Fisher will discuss during the seminar. First of all, she argues that people are attracted to others most like themselves.
"We do know that people are attracted to those people in their same general level of intelligence, religious values, education, degree of good looks and sense of humor," Ms. Fisher says. "Then it becomes timing. And exchange is important: whether you fall in love with people who want what you can give and you can get what you need."
Second, Ms. Fisher hypothesizes that people also are subconsciously attracted to persons who have contrasting genetics from themselves.
"We tend to be attractive to people who are somewhat different from us genetically, so you could have a wider array of parenting skills," Ms. Fisher says. "An explorer probably needs someone like the builder to create a solid home life and be faithful and loyal. The builder needs the spontaneous creativity of the explorer."
Whatever classification, the core systems of the brain for romantic love are the same systems that aid people in finding food and water, says Lucy Brown, professor in neurology and neuroscience at Albert Einstein College of Medicine at Yeshiva University in the Bronx, N.Y. She holds a doctorate in neuroscience.
"They form the basis of the reward system," Ms. Brown says. "These systems also help us to form motivation, how to learn to get to food or water. They are systems that help us remember that it was a good feeling, that we want to repeat it."
Further, the core systems in the brain for romantic love are active at an unconscious level, Ms. Brown says.
"These are systems that are active in everyone, like ones that take care of our ability to breathe or stand up against gravity," Ms. Brown says. "They act at a fundamental level."
Although most people think of love as an emotion, other emotions can vary around the core feeling of love, such as anxiety or anger, she says. Further, the other person can become a goal around which to build a life. A subject in one of Ms. Brown's studies serves as an interesting example. The young woman said she hadn't seen her boyfriend in such a long time — two hours. She was arranging her life so she could get to the library to be with him, Ms. Brown says.
Another example is how King Edward VIII gave up the British throne for Wallis Simpson, an American divorcee. During the 1930s, the British monarchy didn't allow royalty to marry divorcees. Rather than keep his throne, Edward VIII gave it up to marry her.
"She was a major goal in his life," Ms. Brown says. "It was his motivation. It was like he was thirsty or hungry for her. His reward systems were activated very much so when he was with her."
Making love last can be influenced by many factors, says Arthur Aron, professor of psychology at the State University of New York at Stony Brook. He holds a doctorate in social psychology.
Living in a war zone, losing a job, living in poverty and having a child die are some major external stressors on relationships, he says. Good communication and reasonable mental health are factors that continue to make the relationship desirable.
"Maintaining being in love requires not only the absence of bad things, but also the presence of something that is engaging and exciting," Mr. Aron says. "Typically in the early stages, that comes from forming the relationship. As that develops, it would be doing things with your partner that are challenging, novel and exciting, but not so overwhelming to be stressful."
For instance, having a child may be overwhelming and not a shared experience for some couples, while other couples may thrive with children.
"If you are depressed or anxious, the relationship is not going to work out very well," Mr. Aron says. "If you are depressed, part of you feels like you are depressed because of your partner. It's hard to live with someone who is anxious and depressed."