Several sources claim that left-handed people have shorter life-spans:

> 
> A left-handed academic from North Dakota has revealed that left-handers tend to die younger than right-handers. The "generally" right-handed population, he asserts, lasts on average to 68.7 years old. The generally left-handed live to just 65. Perplexingly, though, "extremely" left-handed people have an average death age of 67.4. And the ambidextrous fare best of all: their average age of death is just short of 70.
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Source: [The Guardian](http://www.guardian.co.uk/theguardian/2001/feb/05/guardianleaders)

Other examples: [The Straight Dope](http://www.straightdope.com/columns/read/1099/do-left-handers-die-young), [Godlike Productions](http://www.godlikeproductions.com/forum1/message1616090/pg1), [Fun Facts](http://www.funfacts.com.au/left-handed-people-die-earlier/)

I don't seem to understand why handedness would be a factor. There may be more mental friction in having to use right-handed items, but having any impact on your lifespan seems odd.