If left-handers are clumsy, it’s mostly because everything we use every day is designed for right-handers. It’s like saying tall people have bad posture because they can’t sit up properly in compact cars. Power tools, can openers and scissors are obvious, but even the placement of the cord on my iron or my hand mixer make it more likely that I’ll burn myself or make a mess. When I feed my ticket into the Metro turnstile, when I sign a credit-card screen at the checkout, it takes me half a second longer. And I wouldn’t be surprised if we die younger, because half a second can make all the difference in a critical situation.
LINK TO COLUMN: Do left-handers die young? - The Straight Dope