Shyness is a nearly universal human trait. Almost everyone has bouts of it, and half of th

ose surveyed describe themselves as shy. Perhaps because it's so widespread, and because it suggests vulnerability, shyness is often an endearing trait: Princess Diana, for example, won millions of admirers with her "Shy Di" manner. The human species might not even exist if not for an instinctive wariness of other creatures. In fact, the ability to sense a threat and a desire to flee are lodged in the most primitive regions of the brain.

But at some life juncture, roughly 1 our of every 8 people becomes so timid that encounters with others turn into a source of overwhelming dread. The heart races, palms sweat, mouth grows dry, words vanish; thoughts become cluttered, and an urge to escape takes over. This is the face of social phobia (also known as "social anxiety disorder"), the third most common mental disorder in the United States, behind depression and alcoholism. Some social phobics can hardly utter a sentence without obsession over the impression they are making. Others refuse to use public restrooms or talk on the telephone. Sometimes they go mute in front of the boss or a member of the opposite sex. At the extreme, they built a hermitic life, avoiding contact with others.

Though social anxiety's symptoms have been noted since the time of Hippocrates, the disorder was a nameless affliction until the late 1960s and didn't make its way into psychiatry manuals until 1980. As it became better known, patients previously thought to suffer panic disorder were recognized as being anxious only in social settings. A decade ago, 40 percent of people said they were shy, but in today's "nation of strangers" --in which computers and ATMs make face-to-face relations less and less common--that number is nearing 50 percent. Some psychologists are convinced that the Internet culture, often favored by those who fear human interaction, greases the slope from shyness to social anxiety. If people were slightly shy to begin with, they can now interact less and less, and that will make the shyness much worse.

According to Paragraph 1, shyness is ______.

A．against human nature

B．completely an endearing trait

C．so widespread that a problem may arise

D．essential to the survival of the human species