Death Rates Studied : Is the World Really Safe for Lefties?
Is it wrong not to be right?
For all that has been said and done through the ages, one might conclude that being left-handed is something of a misfortune, an unhappy accident. Scissors don’t fit. Neither do standard golf clubs. Tools work backwards. Handwriting slants the wrong way. It’s hard to find elbow room at the dinner table.
Considering everything going against them, lefties point out, they have done quite nicely adjusting to the world around them--and can even count among their ranks some great figures in history: Michaelangelo, Babe Ruth, Thomas Edison, to name just a few.
Research in recent years has begun to shed light on the broad scientific questions about the biological and physiological disadvantages--and advantages--of being left-handed.
Early Assumption
Scientists are beginning to understand, for example, something of how the brain is programmed for left- or right-handedness. While it was once assumed that “handedness” was genetically passed through generations, a growing body of evidence now suggests that left-handedness may be the result of hormonal irregularities or early fetal accidents. These, in turn, seem to generate greater susceptibility to disease and accidents, but they may also result in higher intelligence and greater creativity among some left-handed individuals.
Now the left-versus-right debate is also taking a new, impassioned turn as scientists begin to compare death and accident rates of left-handers and right-handers. The most highly publicized of the studies by two psychologists from Cal State San Bernardino and the University of British Columbia--both right-handers--shows that left-handed baseball players on average live about eight months less than right-handers. The study appeared a year ago this month in the prestigious British journal Nature.
Today, in the same journal, a left-handed statistician from Canada reveals new data showing the opposite--that left-handed baseball players actually live an average of two years longer.
Technical Differences
Whether a right-handed ballplayer is likely to outlive a left-handed ballplayer by a few months or even a few years may seem a somewhat esoteric question. In fact, the debate between the Canadian and Californian researchers hinges partly on highly technical differences in statistical methodologies.
But beyond arguments over what the numbers are and how they should be interpreted lies a long history of prejudice against left-handers.
The fear of left-handedness seems to run deep in man’s collective unconscious. The Bible, the Torah, the Koran--all in one way or other praise the right hand and damn the left. In many cultures, the left hand has been associated with death rituals and superstitions. Even the word left has long had unwelcome connotations. In Middle English, it meant weak or broken. In Latin, it is sinister. In French, it is gauche.
It was nearly 20 years ago that scientists first noticed an unexpected and alarming trend in public-health data regarding left-handers.
It might have been just one of many haphazard pseudo-trends that sometimes emerge from health statistics. But these statistics were particularly striking. At the age of 10, 15% of the population was left-handed. At 20, 13%. By age 50, the figure drops to 5%. And by 80, it’s less than 1%. Beyond that, there are few, if any, left-handers left.
What was the cause of this drop-off? Were left-handers being forced to become right-handed? That seemed unlikely since research had shown that such efforts were not very effective--and, anyway, most civilized countries had long ago stopped the practice of trying to convert lefties to righties.
Problem Is Proof
Perhaps left-handers were dying out faster than the rest of the population. As implausible as that seemed, it was the only explanation that seemed possible. The problem was proving it. There simply was not enough reliable data, especially on people who were already dead. Except for one source: The Baseball Encyclopedia. It was surely the largest and most reliable compendium of data ever compiled on any single group of people. Not only were births and deaths recorded, the left- or right-hand preferences of all players were also faithfully recorded.
Diane F. Halpern of Cal State San Bernardino and Stanley Coren of British Columbia were the first to analyze the baseball data. In looking at players year by year, they found no statistically significant differences at first. But after age 33, the death rates of left-handers accelerate. Overall, what they found was that left-handed ballplayers listed in The Baseball Encyclopedia died, on average, at 63.97 years, while right-handed players died, on average, at 64.4 years.
The difference was small--only eight months--and critics wondered if there wasn’t something unique about professional ballplayers that would make left-handed ones prone to slightly earlier deaths.
Halpern and Coren knew that while eight months might not make a huge difference in any one individual’s life, the difference statistically could be quite significant with large populations. But the researchers, too, wondered if there wasn’t something peculiar about the ballplayers, which would not make their experience generalizable to the population at large.
Did Second Study
The two scientists decided to do another study, this one involving information provided by next of kin of recently deceased residents of San Bernardino and Riverside counties. Once again, left-handers were found to be dying younger than right-handers. That study has yet to be published, but it has been submitted to a scientific journal, and details of it are included in their book, “Laterality and Longevity,” which is now in press.
Max G. Anderson, a private consultant and statistician in Vancouver, was one person who was not impressed with Halpern’s and Coren’s results. For one thing, he just couldn’t believe that there were no lefties over the age of 80. What is more, as he began to look at statistical methodology the scientists had used, he began to suspect that it was flawed.
The sample, he said, was too small and it relied on a method that would result in differences that were not truly statistically significant.
“It’s unfortunate that their study was even published,” Anderson concluded, after doing his own analysis of the encyclopedia statistics, which he said was more reliable.
Anderson does not talk in terms of average longevity because he says such numbers fail to take into account the tremendous increase in the overall life span of Americans over the past century. Average number of years lived also does not account for unexpected rises in death rates caused by such events as flu epidemics.
Variations Disappear
What Anderson does talk about are the overall differences between right-handers and left-handers in specific years. Before 1870, according his analysis, right-handers did live longer--by as much as five years. By 1890, however, the differences had disappeared, and by 1910 the trend had reversed, so that now left-handers are living on average two years longer than right-handers, he said.
Anderson has no clear explanation for his findings except that perhaps the experience of left-handers parallels that of women. While females once seemed to be at a disadvantage to men largely because of a high risk of death during childbirth, females are now at a clear advantage, living, on average, seven years longer than males.
Scientists know of no event, no change, that would suddenly make the world safe for left-handers. And certainly, the critics say, it is highly unlikely that evolutionary change would occur in as short a span of time as Anderson’s numbers would suggest.
In fact, there is a great deal about left-handedness that scientists do not yet understand. They don’t know for sure why or how people become left-handed, although a number of interesting observations made in recent years are now beginning to allow scientists to put together the puzzle of left-handedness.
More than a decade ago, for example, scientists had examined enough fossil evidence--especially tools and early cave art--to conclude that left-handedness had been a characteristic of a small, consistent minority of the population from the Stone Age onward.
Not Simple Genetics
They also realized that left-handedness could not be a matter of simple genetics, passed along like blue eyes and blond hair. There were simply too many left-handed mothers and fathers who produced right-handed children for left-handedness to be a simple matter of recessive genes, Halpern and Coren explain in their forthcoming book.
In the early 1980s, Norman Geschwind, a professor and research scientist at Harvard University, announced that he had found evidence of chemical changes--especially high levels of the male hormone testosterone--that may alter the normal growth pattern of the brain and bring about a tendency toward left-handedness.
At about the same time, scientists also began to observe that left-handedness was also associated with a number of birth traumas, including RH incompatibility, multiple delivery, prolonged labor, breach birth and prematurity. According to a number of studies, more than 50% of all low-birth-weight babies turn out to be left-handed, compared to only about 8% of all other babies.
That left-handedness might be the result of some early neurological insult may explain why left-handers seem to suffer more from a whole variety of problems.
Scientists have found, for example, that lefties are more prone to neuroticism and allergies and insomnia. And, as a group, they are more likely to be mentally retarded and suffer from learning disorders or autism. They tend to have more migraines and to suffer more disorders of the immune system.
More Breast Cancer
Perhaps because of these immunological deficiencies, left-handed women under the age of 45 are more than twice as prone to breast cancer, according to a study done in 1985.
Studies done in 1985 and 1986 suggest a much higher than normal rate of alcoholism among left-handers. Earlier studies, done in the late 1970s, found a similarly high tendency to smoke cigarettes among left-handers.
A study published just last month by Coren in the American Journal of Public Health found that left-handers in many ways lead far more traumatic and dangerous lives than right-handers.
In a four-year study of 1,896 students, Coren discovered that left-handers were 89% more likely to suffer serious accidents. They were 85% more likely to have a car crash, 54% more likely to hurt themselves with tools and 49% more susceptible to serious domestic injury.
Left-handed men are at greatest risk when behind the wheel of a car. According to the study, a left-handed male is 135% more likely to have an accident than a right-handed male while driving a car.
Traffic Patterns
The reason, scientists conjecture, is that roadway traffic patterns favor the clockwise preferences of righties and that gear shifts, power tools and equipment require lefties to make do with their less-dexterous hand or to work in an uncomfortable or hazardous position.
While the hormonal irregularities or fetal accidents may explain the origin of some of the problems, these theories do not account for the many advantages that left-handed people also seem to enjoy.
Studies in the 1970s showed that left-handers were over-represented in a variety of difficult and prestigious professions, including architecture and engineering. Studies in the late 1980s have found abundant evidence that, while some left-handers may have mental disabilities, an even larger number are mentally gifted, scoring extremely high, for example, on standardized tests. Certainly, lefties are among the ranks of the world’s great athletes, artists, musicians, politicians: Sandy Koufax, Lefty Grove, Frankie Albert. Leonardo da Vinci, Pablo Picasso, Paul Klee. Paul McCartney, Jimi Hendrix, Cole Porter. Charlie Chaplin, Harpo Marx, Robert Redford. Julius Caesar, Alexander the Great.
