By nudging women to build networks of support, oxytocin has a powerful indirect effect on their health. At least 22 studies have shown that having social support decreases the heart-racing, blood-pressure-boosting responses that humans and other social animals have to stress and the hormones it sends surging.
When oxytocin levels are high -- even as a result of injection -- reactions to stress are dampened. As a result, stress is less likely to do the kind of physiological damage that can lead to chronic diseases such as heart disease and metabolic disorders. When oxytocin levels are elevated, humans and other social animals also have been shown to heal faster and better from wounds.
Researchers at Ohio State University and Carnegie Mellon University have shown that people who report strong social supports have more robust immune systems and are less likely to succumb to infectious disease. Kiecolt-Glaser, who studies friendship and health, calls social support "the most reliable" psychological indicator of immune response that has been found.
There is even evidence that the broader network of friends and support that women tend to have may protect from the effects of dementia. A large survey of Swedes age 75 and older found in 2000 that the risk of developing dementia was lowest in men and women who maintained a wide variety of satisfying contacts with friends and relatives. The researchers surmised that the mental exercise of juggling many relationships kept the brains of those with rich social networks in better tone.
The health benefits of friendship are not news to Irene Miller, 59, of Woodland Hills. With her friend of 38 years, Anita Kienle, never far from reach, Miller has weathered the dissolution of her first marriage, depression and a malfunctioning thyroid gland. She, in turn, helped nurse Kienle, now 63, through breast cancer a decade ago. "I know this friendship has gotten me better from psychological and physical illness," she says. "You don't have to show me rats in a maze."
In 2000, when ovarian cancer survivor Jewel Williams met Faye Anderson of Compton, then a newly diagnosed breast cancer patient, she recognized a woman in need of a friend.
"I took her under my wing," says Williams, now 67, of Los Angeles. "I just knew it was in God's plan for me to stick with her and get her through the tough times." Today, Williams and Anderson, 63, visit and talk regularly on the phone, and the friendship is one of many that Williams says has filled her life with joy and purpose, and "kept me from going into a shell."
Male friendships not the same
But are women's friendships uniquely health-promoting? Do women glean benefits from their women friends that could not be gotten from boyfriends or husbands?
Among researchers, the answer is a definite maybe. Girlfriends, however, are unanimous: The answer is yes. "With women, you can bare your soul. You don't do that with your husband, and they don't do that with you," says Suzanne Dragge, 82, of Pasadena. She and her friend Connie Smith, 85, have counted church offerings, kidded each other and fly-fished together for almost a decade. "Thank goodness for lady friends."
In fact, for women, there is some evidence that a male partner, in times of stress, can make things worse. In a study published in the journal Psychosomatic Medicine in 1995, German researchers found that when subjects were given a stressful task -- in this case, preparing a speech for delivery in front of an audience -- men who were joined by their female partner for the preparation period showed much lower stress levels than those who had no support. For women, it was a different story. When women preparing their speeches were joined by their male partners, their stress hormones surged.
Taylor of UCLA surmises that findings such as this may reflect a major difference between the way men and women give support. Men's support to a friend or partner tends to take the form of advice, she says. Women's support more frequently comes in vaguer forms of encouragement, validation and acceptance. That, in turn, may let a woman work out her own solution to a problem, with less pressure to satisfy the expectations of her advisor.
Kiecolt-Glaser adds that differences in the ways that men and women converse may result in large differences in their social supports.
"Women tend to talk about feelings, whereas men tend to talk about events," says Kiecolt-Glaser.
On meeting a friend, a man may open a conversation with a comment on sports. By contrast, a woman is more likely to spill a personal problem -- 'I'm having a tough time on my job' or 'my kids are driving me crazy' -- right from the start.
"It's the self-disclosure aspect of the conversation that matters" to women -- and which leads to supportive comments and validation from a friend, says Kiecolt-Glaser. "To say 'what a pity about the Sox' is not exactly a way to evoke warm support from others," she says.
As Kris Frieswick, a 41-year-old business columnist in Boston, says of self-disclosure among her circle of eight friends: "It's what you do ... you spill."
She adds: "That's the basis of our mutual relationship, the mutual spilling, the purging and not being judged ... these are women who accept you totally."
For the last decade, says Taylor, researchers have been scrambling to overcome decades of neglect in studying the factors that uniquely affect women's health. From the Bible's Ruth and Naomi to "Sex and the City's" quartet of friends, stories abound, but rigorous study of women's friendships remains in its infancy. Scientists, she adds, need a "wake-up call" to take it further.
"This is one of those areas that is relegated to nice stories and pretty prose rather than hard science," Taylor says. "What this body of evidence suggests is that there's an important biological role for women's friendships that scientists have largely ignored."