The Equation of Love
by Nadia Hoppe, Assistant Editor

It’s March! The sparks of Valentine’s Day are still sizzling, and love is still in the air. Love, arguably most powerful feeling in humans, is a mystery to all of us. But TIME magazine has let its readers in on the science behind romance in Jeffery Kluger’s article, “Why We Love.” While you might think the science behind love is our desire to continue our race, a.k.a making babies, Kluger proves it to be much more. Our race cannot continue without reproduction, as a human cannot live without food, yet a celibate person can live whereas a starving one cannot. "People compose poetry, novels, sitcoms for love," says Helen Fisher, an anthropologist at Rutgers University and something of the Queen Mum of romance research. "They live for love, die for love, kill for love. It can be stronger than the drive to stay alive."
Yes, we all know that people all around the world are in love with falling in love, but why? Scientists are approaching the answer and finding out that it is not only their personalities, or just how darn cute they are, but it’s also the visual, auditory, olfactory, tactile, neurochemical processes that drive us crazy in love.
As soon as our bodies reach physical maturity, we learn to look for the good reproductive genes in others and how to flaunt our own with the ultimate goal of mating. One of the most primal of these is smell. This means that it was not the Abercrombie and Fitch cologne your last boyfriend wore that made him oh, so irresistible, but our animal instinct to be attracted to good scents. Just as we are attracted to good smells, our bodies shy away from bad ones, like the smell of something rotting, warning us against the dangers.
Not only do we recognize the smell of perfumes and colognes, but we also recognize subtle smells, indicating the natural bodily cycles in others. Women recognize this in each other, often syncing with those they spend the most time with. Men, on the other hand, react to these subtle scents in a different way. According to a study published last October in the Journal Evolution and Human Behavior, men find women more or less attractive depending on what part of the cycle they are experiencing. Another study, conducted by Martie Haselton, an associate professor of psychology at UCLA, found that in different parts of these cycles, men in a relationship are more loving and attentive and, significantly, more jealous of other men.
Another way we choose our mates through scent is our recognition of major histocompatibility complex, or MHC. These are genes that control the immune system and can influence tissue rejection. If you try to conceive a child with someone whose MHC is too similar to your own, then the risk of expelling the fetus increases. MHC is not only detected through smell but also through taste. That’s right, kissing! Saliva containing this compound can serve as a test for the partner’s MHC and make or break the attraction.
The way your partner looks, of course, can add to the attraction. It has been shown that curvier body types for women are found more attractive by men because it suggests a body ready for baby bearing. Women, on the other hand, find men with stronger body types more attractive because they look for someone who can protect them and their babies. In the same sense, the sound of a person also causes attraction. Researchers at the University of Albany recently conducted related research where they had a group of 149 volunteers listen to recordings of men's and women's voices and then rate the way they sound on a scale from "very unattractive" to "very attractive." The voices rated “very attractive” happened to be the voices of women or men with attractive features.
But, as we know, attraction is not only about mating, but also about love. So, when does it go from finding a good mate to falling head over heels in love? Studies of the brain show that functional magnetic resonance imagers (fMRIs) are the answer. The earliest of these were taken in 2000 and showed that love affected three parts of the brain. The first is the ventral tegmental, a clump of tissue in the brain's lower regions, which is the body's central refinery for dopamine, the regulator of rewards. For example when you hope for that A on your physics test, and find out after waiting a week that you succeeded in your goal, that jolt of good feeling is dopamine. Accordingly, fMRI scans of those newly in love show the ventral tegmental is working extra hard. Dopamine might spark the good feeling, but the brain's nucleus accumbens, located slightly higher and farther forward than the ventral tegmental, is what keeps it around. The brain’s nucleus accumbens create a substance called oxytocin, the chemical meant to bind. It is what binds new mothers to their babies as it floods through their bodies during labor.
Love is not always as clear as a good smell or a hot bod, and even our own body can fool us when picking the perfect mate. Birth control pills and adrenaline can be our downfall. Birth control, blocking the scent of MHC, can help the bad ones slip past our perimeters. Adrenaline can do the same, distorting our perception on situations and causing us to take a risk that could later do more bad than good. Brains can also lead us into obsession and the grief of unrequited love. When people fall in love, there is activity in their caudate nucleus, which happens to be adjacent to the part of your brain, which controls addiction, the reason moving on from an old love can be so hard.
Although love can be bad and love can be good, love is adaptive. It can go from the passion of new love to playing board games in the rain and taking care of children. It is undeniable that love is a powerful, mysterious part of human life. Science might give us clues to as why we are attracted to others, but it will never be able to explain the true depths of love. So, next Valentine’s day, keep your nose clear for MHC and your body flowing with oxycotin and do what the day was made for: fall in love!