When Sens. Barack Obama and John McCain take the stage for the presidential debates, attentive viewers may notice both candidates scribbling notes with their left hands. Political junkies will remember that such a curiosity has occurred before: In 1992, all three contenders -- George H.W. Bush, Bill Clinton and Ross Perot -- were southpaws.

In the race for the White House, lefties seem to have the upper hand. No matter who wins in November, six of the 12 chief executives since the end of World War II will have been left-handed: Harry Truman, Gerald Ford, Ronald Reagan, the elder Bush, Clinton and either Obama or McCain. That's a disproportionate number, considering that only one in 10 people in the general population is left-handed.

For years, left-handedness was not treated as a point of pride, much less a qualification for high office. Remnants of anti-leftiness are everywhere: A right-hand man is indispensable, but who wants a dancing partner with two left feet? The words "adroitness" and "dexterity" derive from the French and Latin words for "right," while "gauche" and "sinister" derive from the words for "left." In the New Testament, the souls of sinners who fail to meet with the Savior's approval are sent to his left -- and to eternal damnation. No wonder that, well into the 20th century, children who showed signs of left-handedness when writing were forced to switch hands.



Even today, left-handers are thought to be accident-prone (not true), and a study once showed them to be at risk for early death (it was debunked). But what about their brains? Is it possible that right- and left-handed people -- and presidents -- think differently?

Perhaps. Some left-handers may be better armed for the challenges of leadership because of the way their brains handle language and dexterity (sorry, there's no other word). For nearly all right-handers, language abilities reside exclusively on one side of the brain -- usually the left, which controls the right hand. But one in seven lefties process language on bo th sides of the brain, possibly because using their left hands during childhood stimulated the development of the right half. So Reagan, Bill Clinton and Obama may have left-handedness to thank for their legendary speaking abilities.

The benefits of being a lefty aren't only verbal. Many artists and great political thinkers were lefties -- Pablo Picasso and Benjamin Franklin, for example. Lefties are overrepresented among the mathematically talented and are also more likely to find unexpected or counterintuitive solutions on problem-solving tests.

So maybe the number of left-handed presidents isn't so surprising after all. But why did they only start popping up in the past 50 years? Probably because before that, many lefties were turned into righties by stern tutors and teachers, so few presidents before World War II would have been officially left-handed. In fact, the only known left-handed president before the turn of the 20th century was James Garfield. He was ambidextrous, and legend has it that he could write in Latin with one hand while simultaneously writing the same sentence in Greek with the other. Talk about a way with words.

Then again, we know of no historical evidence to suggest that Abraham Lincoln was left-handed, and he had an even better way with words. The first President Bush, on the other hand, was a southpaw but wasn't exactly known for his silver tongue (more like a silver foot, in the late Ann Richards's inimitable phrase). So should we add left-handedness to the requirements for U.S. presidents? As two right-handed scientists, we recommend some . . . evenhandedness.