If Barack Obama, the wildly popular Illinois senator, pulls off the Democratic Party nomination, as it increasingly seems like he might, the United States will be guaranteed to have yet another left-handed president.

That's because he'll be running up against John McCain, who has been all but crowned the Republican nominee, and is also left-handed.

Not that such a feat would be coming out of left field. Four of the last six presidents have been left-handers. If Obama or McCain wins, it will be five of seven.

So a leftie in the Oval Office isn't unique. But dominating the Oval Office is unusual, considering left-handers make up less than 12 per cent of the population at large.

Why this presidential propensity? There are some loose theories about left-handedness in general, how southpaws tend to be overrepresented among the highly intelligent, more flexible and resilient in a right-handed world.

But the bottom line is a question of politics, psychology, neuroscience and chance, and no one knows the answer.

Toronto entrepreneur and lefty activist Lawrie Weiser, however, has a hypothesis.

"Cream," he says, matter-of-factly, "rises to the top."

That's perhaps predictable from Weiser, who stores all kinds of left-handed products in a broom closet at home and sells them over the Internet.

Even someone who has studied the left versus right brain, as well as handedness, for decades, can't resist.

"There is this old saying that the left-handers are the only people in their right minds," says Joseph Hellige, a neuropsychologist at Loyola Marymount University in Los Angeles. "But that's probably a stretch."

Hellige adds, "I've noticed this president thing over the last 35 years. It's just so interesting. But none of us really know (why)."

Outside the pampered confines of the White House, life for lefties can be hard. Power tools, scissors, can openers, stick shifts, guitars, violins, golf clubs, catcher's mitts, notebooks and binders – for the most part, they're all for the righties.

Toilet paper dispensers are typically on the right. So is the wheel on a Blackberry. So is the mouse for your computer.

One of the few times we give a big job to the left hand – the proper use of the fork – we kind of mask it by giving the right hand something to do at the same time, so it doesn't feel left out.

Some activist groups continue to denounce policies that one might describe as "rightist."

The Handedness Research Institute at Indiana University, for instance, points out the discrimination in educational institutions having too few left-handed desks.

"Left" even has a negative connotation in language. It has long been associated with the devil. Witches were said to greet the devil and perform black magic with the left hand.

In French, it's gauche, which also means awkward or improper.

In Latin, it's sinister, which we take to mean evil or unlucky.

"This is how the language has discriminated against us," notes Toronto's Weiser, whose Internet presence is playfully called sinistershop.com.

"Don't use 'right' when you mean 'correct,' " he advises.

Certain perceptions of left-handers haven't helped. Some researchers have suggested lefties are more likely to be schizophrenic, dyslexic, stutterers, and suffer from allergies, asthma and breast cancer.

Never mind that Michael Peters, a professor of neuropsychology at the University of Guelph, published a study in December 2006 debunking many of these claims. Using a survey of more than 200,000 respondents, the study concluded that left-handedness was not linked to dyslexia, asthma, hyperactivity or homosexuality, as some had suggested.

The bad rap has meant that, at one time, families tried to literally beat children's lefty habits out of them. Parents would swat their child's left hand if they showed a tendency to write or eat with it.

Most animals do not appear to show a preference for left or right, although some research suggests otherwise. One study demonstrated that wild chimpanzees favour one side or the other depending on the task at hand, such as using the right for cracking nuts and the left when fishing for termites.

But for as long as there have been humans, there have been lefties. That has led scientists to posit that left-handedness had some sort of survival benefit. Ancient left-handed warriors would have had an advantage in battles, attacking opponents from an unsuspecting side. Lefties might also add diversity to the population, making it genetically fitter.

And studies have shown lefties to be exceptional. Australian research has found that lefties think quicker when playing computer games or sports. They tend to earn more money, too.

They include the likes of Albert Einstein, Isaac Newton, Leonardo da Vinci and Michelangelo.

They're overrepresented in Mensa, the high-IQ club; among those gifted at high-level mathematical reasoning; among those with higher education degrees; and, most starkly of all, among American presidents.

At least we might understand that presidents tend to be of the ilk of the higher educated.

"It might be statistical artifact," says Loyola's Hellige, "that presidents come from people with some kind of advanced degree, and the proportion of left-handedness tends to be higher among those groups."

Since it's a right-hander's world, lefties, Peters says, have to be more resilient in life – a trait that might be suitable for presidents.

Loading... Loading... Loading... Loading... Loading... Loading...

"I have a son who's left-handed," Peters says. "The fact is when you set the table for him, you don't think about it. I'd plunk the spoon on the right when he was little, and he'd reach over and grab it with his left."

Having to get by in a world that was seemingly built through the looking glass teaches them to be "slightly more resistant to social pressures, to have more of an independent streak."

Other Canadian research has shown lefties to be more adaptable in doing tasks with their non-dominant (right) hand compared to right-handers using their left. Again, probably a good trait for a president.

These are just theories, of course. It could be pure coincidence that some 66 per cent of presidents in the last 30-some years have been lefties.

Bill Clinton was. And before him, George H.W. Bush; the ever-popular Ronald Reagan (a natural-born leftie who ended up writing with his right); and Gerald Ford.

It could be coincidence. "But certainly, when you're looking at about 10 per cent, the odds of having that many left-handed presidents is very low," Peters surmises.

One thing is sure: Left-handed does not correlate with left-wing, considering that three of the above four were Republicans.

The Canadian experience offers no help. It appears that no Canadian prime minister during that time was left-handed. Other left-handed U.S. leaders include Harry Truman, Herbert Hoover and James Garfield. There have been theories as to how left-handedness happens: an overabundance of testosterone in the womb is one; brain trauma at birth is another.

Then, last year, a long-suspected genetic component was found. Scientists at Oxford University identified the LRRTM1 gene, which appears to increase the odds of being left-handed.

While the gene may also raise the risk of schizophrenia, the scientists said it plays a role in which half of the brain controls speech functions.

For the most part, the two halves of our brains work in concert, Peters emphasizes. But there are some notable differences.

In terms of physical movement, the left brain controls the right side of our body, and vice versa.

Speech is not so easily isolated. Right-handers' speech centres are located in the left brain. So are two-thirds of left-handers'.

That still leaves more left-handers using the right brain for speech. What's the difference? While the left brain is more concerned with speech syntax and order, the right is involved in monitoring the overall context and emotive quality.

"You're listening to specific things I say," Peters explains. "The broader meaning, where I put emphasis, word melody, that's all done by the right hemisphere and understood by the right hemisphere."

He offers an example: If you give someone a gift and they happily squeal, "Oh, I could just kill you!," the left brain would literally understand it as your friend wanting to kill you. It's the right that would get the nuance.

In this heated U.S. primary race, Obama is the one with momentum. And much of that has been largely attributed to how his inspirational oratory has captured the imagination of voters, including the previously apathetic and cynical.

Could this be his right brain talking and our right brains listening?

The experts don't think so. Political psychologist Dean Simonton at the University of California at Davis, who studies leadership, says left-handedness actually works against Obama's allure. In fact, he points out, "any relevant findings go in the wrong direction. For example, left-handedness is more strongly associated with stammering, stuttering, and dyslexia."

"To the best of my memory, John Kennedy wasn't left-handed," adds Hellige, author of the book Hemispheric Asymmetry: What's Right & What's Left.

"A lot of inspirational speakers aren't left-handed."

For further evidence of that, you need only look to the other front-runner: John McCain, for whom eloquence is not attributed and awkwardness sometimes is – lefty status notwithstanding.

Read more about: