From cradle to an earlier grave, lefties struggle with a built-in bias toward right-handed people. Roughly 10% of the population is left-handed, but all standard mass-produced facilities are designed for right-handed people. Even the fly on your trousers is designed to be used with the right hand. As a result of this persistent right-handed bias, some studies suggest that left-handed people may live longer.
The ratio of left-handed people changes with age. It is higher among younger people and lower among older people. Among young adults, roughly 10-15 percent are left-handed. However, among 50-year-olds, 5 percent will be left-handed. Just 1 percent of 80-year-olds are left-handed. This cross-sectional decrease with age is commonly considered to be evidence of a shorter lifespan for left-handed people than for right-handed people.
However, older people have had much more experience in dealing with a right-handed world. They are also much more likely to have been forced to write with their right hands in school. Because extreme handedness is uncommon for either hand, many left-handers may have learned to become right-handers over time. Thus, these figures by themselves do not prove that left-handed people tend to have shorter lifespans than right-handed people.
Left-handed people are more likely to have accidents. This is probably because of the persistent right-handed bias in their environment.
In a 1989 study of nearly 1,900 college students, left-handed students reported more accidents than right-handed students. Car accidents were especially common.
Another study found that the risk of death by accident was 6 times higher for left-handed people than for right-handed people. The same study also found that right-handed people lived an average of 9 years longer than left-handers.
A 2008 study has found that the ratio of left-handed elderly people in cardiac rehabilitation units was higher than among healthy same-age people in the general population. This follows up on a 2007 study which found that left-handed women had higher rates of heart and blood vessel disease. The same study also found an increased risk of colorectal cancer among left-handers.
This could show that whatever causes left-handedness could also predispose a person to heart disease. However, it could also show that left-handers are under greater lifelong stress than right-handers. The link between heart disease and stress has been well-researched. A few studies have also found that colorectal cancer is more common in highly stressed people, although the science here is not clear.
The stress of being president
Before 1974, the number of known left-handed U.S. presidents roughly matched the ratio of left-handers in the general population. Only 2 are known for sure, Herbert Hoover and Harry S. Truman, although James Garfield may have been ambidextrous. Truman is also sometimes considered to be ambidextrous.
However, against the odds, 5 of the last 7 U.S. presidents have been left-handed: Gerald Ford, Ronald Reagan, George H. W. Bush, Bill Clinton and Barack Obama. Ronald Reagan became ambidextrous as a result of being forced to write with his right hand in school.
In two elections, both the Republican and Democratic candidates were left-handed, guaranteeing a left-handed president. This happened most recently in 2008, where the candidates were Barack Obama and John McCain. In the 1992 election, all three major candidates were left-handed: George H. W. Bush, Bill Clinton and Ross Perot. This was repeated in the 1996 election with two of the same candidates, although Bob Dole was actually a right-hander who had learned to use his left hand after a World War II injury.