What science says about those tender feelings. Love has toppled kings, inspired poets, sparked wars, soothed beasts, and changed the course of history. It is credited for life's greatest joys, blamed for the most crushing sorrows. And, of course, it makes the world go round.
All of which is no surprise to biologists. They know that love is central to human existence. We are not just programmed for reproduction: the capacity for loving emotions is also written into our biochemistry, essential if children are to grow and thrive. Love's absence can be devastating: the loss of a spouse often hastens death in older people.
Now researchers are beginning to sort out how body and mind work together to produce the wild, tender, ineffable feelings we call love. They have found, for example, that oxytocin, a chemical that fosters the bond between mothers and children, probably helps fuel romantic love as well. Brain chemicals that blunt pain and induce feelings of euphoria may also make people feel good in the company of lovers.
Far from reducing love's thrill to dry facts, biologists' efforts underscore the emotion's importance.'We evolved as social organisms, ' says University of Maryland zoologist Sue Carter.'The study of love tells us that we have a biology that allows us to be good to each other.'
Love began with motherhood. For mammalian young to survive, mothers must invest considerable time and energy in them. When females of most mammalian species give birth, their bodies are flooded with oxytocin, known since 1906 as a hormone that stimulates uterine contractions and allows the breasts to'let down' milk. But oxytocin also acts as a neurotran-smitter, or chemical messenger, that can guide behaviour. Without it, a ewe cannot recognise her own lamb.
Oxytocin has even more dramatic effects on human mothers, inducing a tender openness that fosters maternal devotion. As a mother breastfeeds, oxytocin levels rise in her blood. She also scores higher on psychological measures of'social desirability', the urge to please others, according to Kerstin Uvnas-Moberg of Sweden's Karolinska Institute.
Mothers with higher levels of oxytocin are more sensitive to other people's feelings and better at reading nonverbal cues than those with lower levels. This makes sense, says Uvnas-Moberg, because oxytocin is thought to bind to centres in the brain involved with emotion. It also acts as a natural tranquil-iser, lowering a new mother's blood pressure, blunting her sensitivity to pain and stress, and perhaps helping her view her child more as a bundle of joy than as a burden.
Studies of a small rodent known as the prairie vole, a cuddly ball of fur whose mating bond of lifelong monogamy would put most human couples to shame, indicate oxytocin may also play a role in the heady feelings associated with romance.'You just can't imagine how much time these animals spend together, ' says Carter. The voles' undying devotion is the work not only of oxytocin but also of a related hormone, vasopressin.
When single male and female prairie voles meet, they commence a two-day-long bout of sex that releases oxytocin in the female's brain, bonding her to the male. Deprived of the chemical, she finds him no more appealing than any other vole. Vasopressin inspires similar ardour in the male, who prefers his mate's company above all others, guarding his family against intruders with a jealous husband's zeal.
Love's other messengers in the brain are the endorphins, or brain opiates, the body's own version of drugs such as heroin and morphine. High levels of brain opiates kill pain and induce a state of happy relaxation. Low levels are associated with unpleasant feelings. The power of endorphins to affect mood may play a crucial role in bonding. Compelling evidence comes from recent studies of female talapoin monkeys, animals that form what in humans would be termed friendships.
Barry Keverne, a primatologist at Cambridge University in England, has found that when talapoin friends who have been separated are reunited, they commence grooming enthusiastically; and their endorphins double. Research on opiates suggests the flip side of love is not hate, but grief.'Biochemically, loss of love, or grief, is the inverse of love, ' says Keverne.
Passionate love affects the whole body, setting the heart pounding, making the stomach do flip-flops, and of course, lighting the loins on fire. These visceral sensations are the work of the vagus nerve, which traces a meandering path through the body, coordinating the activities of internal organs, says the University of Maryland's Stephen Porges. Without the vagus, says Porges, love would be impossible.
One part of the nerve is evolutionarily ancient, controlling primitive functions such as sex, hunger and fear. This'old' vagus responds to oxytocin and serves as the pathway between sexual organs and the brain for feelings of both arousal and satiation after sex. But Porges argues that in mammals, newer branches of the vagus also connect emotional brain centres with the heart, the face, and the vocal equipment, helping to coordinate feelings with facial and verbal expression. The'new' vagus also helps slow the heart and keep the body calm enough for the brain to pay attention to emotional signals from other people.
In other words, the poets and bards were right about one thing: The heart speaks the language of love. As English poet W.H. Auden wrote, Where love is strengthened, hope restored, In hearts by chemical accord.It may not literally skip a beat at the sight of one's desire or break with sorrow, but the heart's rhythms are exquisitely tuned to love.
Scent of love
The key to starting a love affair might be right under your nose. Scientists have discovered a virtual sixth sense, a tiny organ in the nasal cavity that responds to chemicals known as pheromones, natural substances that influence human emotions such as fear, hunger and love.
Scientists had long thought that in humans this pheromone-sensing organ was merely a nonfunctional holdover from the past. But David Berliner, a US anatomist formerly with the University of Utah who made millions in Silicon Valley's biotechnology revolution, spurred research into the organ's properties. He has shown that, in fact, the organ actively responds to nearly a dozen chemicals produced by human skin.
Berliner's team found that several human pheromones appear to be sensed only by males or by females, suggesting that they serve as signals between the sexes. In animals such as hamsters and pigs, a single whiff of a pheromone temporarily turns the animals into sex fanatics.
Encouraged by these animal models, perfume companies have long used the pheromones of various animals-like musk from deer-in their concoctions, both as a scent and as a preservative. But research reveals that animal pheromones have an effect only on members of the same species.
The main effect of the pheromones appears to be not torrid passion but merely a general feeling of well-being. In fact, Berliner's spinoff perfume company, called Erox, is designing fragrances that have their main effect on the wearer, not on the opposite sex.
The putative effect will be to make the people feel more confident and easygoing-which may put them more in the mood for socialising and, perhaps, a little romance.
Smitha Marar
malayalam manorama
