"Did you know that all of us are born right-handed but only a few of us outgrow it?" quips Ken Ahrens, executive secretary of the National Association for Left-handed Golfers.

Lefties have been a fairly constant 10 percent of the world's population for the past 5,000 years. More recently (in 1975) an association, Left-handers International (LI), was formed to battle injustices and inconveniences in a right-handed world. Left-handers, they will tell us, have plenty of reason to gripe.

Consider just one example among the tales of bumping elbows and clumsiness with scissors: Lefty reserve trooper Woody Winborn was fired several years ago from the Riverside, Mo., police force for refusing to wear his holster on his right side. Explained Police Chief Jerry Wingo, who wanted a "more disciplined organization": "You have to make everyone follow the same regulations or relieve them of their duties."

Winborn repeated his safety concerns in a local court, won his case, was reinstated and--satisfied--promptly resigned.

"Left-hander is a shorthand term to mean non-right-hander," says Dr. Jerre Levy, professor of behavioral sciences and researcher in brain organization at the University of Chicago.

"A true right-hander seems to be strongly right-handed for just about any skill or manual activity that anyone can think of. But the people who don't fall into that category are not mirror images of right-handers. Many prefer using their left hand for some activities and the right hand for others."

Levy describes these people as "ambilaterals" rather than "ambidextrous." An ambidextrous person, she explains, would have equal dexterity with both hands for all activities. "In actuality, I've never seen one."

Testing our population for the degree of preference or skill of the two hands, scientists find most people (70 to 80 percent) are all lumped together as strongly right-handed at one end of the scale. "Then," says Levy, "we have a very long tail that extends to the strongly left-handed (5 percent) at the other end," with ambilaterals falling in between.

It is estimated that 10 to 12 percent of Americans now write with their left hand, up from 2 percent in 1930 when teachers and parents made many children go against their natural inclination. "If you live in a culture which forces people to use the right hand," says Levy, "the vast majority of people can adjust."

Although Levy does not believe that forcing a child to use the non-preferred hand produces neurological changes in the brain, she does see negative psychological consequences. "The child is simply put in a very difficult situation."

There are, Levy believes, several causes for left-handedness: possibly a normal genetic variation, some unknown stress on the brain experienced prenatally or during the birth process, or simply an early injury to the right hand so that a child learns to use the left and then continues to do so.

While all strongly right-handed people have the same, or standard pattern of brain organization, "Left-handers," says Levy, "have every possible form of brain organization that you can imagine." She maintains that generalizations are impossible.

Dr. Norman Geschwind, a Harvard Medical School neurologist and head of the neurology department at Beth Israel Hospital in Boston, and Glasgow University neurologist Peter Behan recently completed studies that show left-handed people and their relatives have nearly three times more autoimmune diseases, in which the immune system itself attacks the body. (Not to be confused with AIDS, or Acquired Immune Deficiency Syndrome, in which patients develop a severe loss of natural immunity.)

Although lefties have a greater risk of diseases such as ulcerative colitis in which the body mysteriously attacks its own tissue, "My bet," says Geschwind, "is that they have lower rates of certain other diseases like bacterial infections and many cancers."

The two scientists also found strong left-handers have 10 times as high a rate of dyslexia and stuttering compared with strong right-handers, as well as much higher rates of childhood allergies.

On the good news side, Geschwind cites left-handers' unusual numbers in the visual arts (Michelangelo and Leonardo da Vinci) and architecture and their frequent excelling in sports.

Geschwind believes that when left-handedness is present, it is a clear marker of a different organization in the left and right hemispheres of the brain.

In the vast majority of brains, the planum temporale, an area involved in speech, is much larger in the left hemisphere than in the right. In strongly left-handed people, says Geschwind, the usual asymmetry may be disturbed: The planum temporale is the same on both sides or larger in the right hemisphere.

The different brain pattern may be a result of slow fetal development of the left side of the brain (possibly because of the male sex hormone testosterone, according to Geschwind), allowing the right side to develop superior spatial function. Studies have shown testosterone interferes with the development of the immune system, particularly the thymus gland.

Geschwind--a staunch defender of left-handers' abilities--says that while right-handers are faster and more accurate with the right hand or leg, left-handers, with their more symmetrical brains, have arms and legs of more equal ability, an asset in sports.

"If someone is going to catch a pass in football," says right-hander Geschwind, "he's got to make some tremendously complicated spatial calculations which could give lefties an edge to be in just the right place at the right time."

Although no one knows for certain what their specific mode is, southpaws--it is clear--deserve respect. And that's not a left-handed compliment.