Even when women do decide to breast-feed, they sometimes feel they are thwarted by their own bodies. \"Insufficient milk\" is cited as a major reason women in the West terminate breast-feeding after a few days or weeks. The syndrome is fascinating because it is a clear example of a disease being \"invented,\" defined, and then perpetuated by culture at large. In only about 5 percent of the cases is there something making it physically impossible for a woman to breast-feed. Before bottle-feeding came into vogue, women rarely, if ever, reported a lack of milk. But when breast-feeding went out of fashion in the 1940s, this new syndrome appeared. The real cause of insufficient-milk syndrome appears to be a confluence of social changes—hospitals took over the birth process and separated newborns from their mothers, doctors recommended interval feeding, and artificial formula presented a reasonable alternative. It is interesting to note that insufficient-milk syndrome appears only in Western industrial nations and has yet to be found in other cultures. Why do so many women in affluent countries say they have no milk for their babies?

A problem that did not exist before the introduction of bottle-feeding.

Before 1980, this would have seemed a strange question. Social anxiety disorder did not officially exist until it appeared in that year’s Diagnostic and Statistical Manual, the DSM-III, the psychiatrist’s bible of mental disorders, under the name “social phobia.” It was not widely known until the 1990s, when pharmaceutical companies received F.D.A. approval to treat social anxiety with S.S.R.I.’s and poured tens of millions of dollars into advertising its existence. The current version of the Diagnostic and Statistical Manual, the DSM-IV, acknowledges that stage fright (and shyness in social situations) is common and not necessarily a sign of illness. But it also says that diagnosis is warranted when anxiety “interferes significantly” with work performance or if the sufferer shows “marked distress” about it. According to this definition, the answer to our question is clear: the young woman in the ad is indeed sick.

The DSM inevitably reflects cultural attitudes; it used to identify homosexuality as a disease, too. Though the DSM did not set out to pathologize shyness, it risks doing so, and has twice come close to identifying introversion as a disorder, too. (Shyness and introversion are not the same thing. Shy people fear negative judgment; introverts simply prefer quiet, minimally stimulating environments.)

But shyness and introversion share an undervalued status in a world that prizes extroversion. Children’s classroom desks are now often arranged in pods, because group participation supposedly leads to better learning; in one school I visited, a sign announcing “Rules for Group Work” included, “You can’t ask a teacher for help unless everyone in your group has the same question.” Many adults work for organizations that now assign work in teams, in offices without walls, for supervisors who value “people skills” above all. As a society, we prefer action to contemplation, risk-taking to heed-taking, certainty to doubt. Studies show that we rank fast and frequent talkers as more competent, likable and even smarter than slow ones. As the psychologists William Hart and Dolores Albarracin point out, phrases like “get active,” “get moving,” “do something” and similar calls to action surface repeatedly in recent books.

Shyness becomes \"Social Anxiety Disorder\" because we live in a society that values outgoing people over people who are introspective.