Psychologist Stanley Coren's Bad News Comes Out of Left Field—Lefties Lead Riskier, Shorter Lives
updated 11/06/1989 AT 01:00 AM EST
•originally published 11/06/1989 AT 01:00 AM EST
According to Dr. Stanley Coren, an experimental psychologist at the University of British Columbia, being a lefty may actually be hazardous to your health. Coren, 47, who has been studying "sidedness" in humans and animals for 20 years, recently detailed the results of studies showing that left-handed people, on average, have a 1 to 2 percent chance of dying younger than right-handers—mostly from accidents. Coren is one of the lucky 90 percent of the population who are right-handed, lie elaborated on his surprising findings and discussed southpawedness in general with correspondent Doris Klein Bacon, a left-hander.
Is life really more hazardous for lefties?
Yes. Lefties are five times more likely to die in accidents, and studies show that from middle age on, lefties are somewhat more likely to die sooner of other causes.
How did you arrive at your findings!
Back in 1979 my colleague Dr. Clare Porac, professor of psychology at the University of Victoria [British Columbia], and I conducted a study of about 2,000 people ranging in age from 8 to 100. We discovered that 13 percent of the 20-year-olds were left-handed. But we were surprised to discover that among the 50-year-olds, only 5 percent were left-handed. And when we got to the 80-year-olds, less than I percent were left-handed. That suggested the macabre possibility that left-handed people have somewhat reduced life spans as compared with right-handed people.
How do you know the lefties weren't learning to do things right-handed as they got older?
Other research has shown that it is fairly difficult to change handedness—it's only successful in one of every three or four cases, and then only if you catch the individual quite young, and then only for the targeted behavior. So that if you learn to write with your right hand, you'll still brush your teeth with your left.
What did you do next?
Well, initially the results seemed strange to me too. So another colleague, Dr. Diane Halpern [professor of psychology at California State University, San Bernardino], and I decided we needed to study a special sample of people, all of whose handedness we knew, and all of whom were dead. We chose professional baseball players, taking advantage of the fact that professional baseball is statistics mad. Of the 2,300 major-league players we looked at from 1880 to 1975—we excluded switch-hitters and players who batted one way and threw the other—we found no difference in death rate until they reached the age of 33. After the age of 33, the left-handers were 1 to 2 percent per year more likely to die than the right-handers.
That's not a big difference. Couldn't it have been coincidence?
Yes, and we didn't know the causes of death. So in a recent unpublished study done with Dr. Halpern, we did a random sampling of death records in Southern California. We contacted the next of kin of about a thousand people who had died in the preceding year. We found that lefties were more likely to die in accidents. The world is organized for right-handers.
Which accidents were most common?
Lefties were 85 percent more likely to be injured in auto accidents than righties and 54 percent more likely to suffer injuries in accidents involving tool or implement usage. Our study indicated that the biggest hazards in the workplace involve large cutting tools.
Most people don't work in machine shops. Are your findings really representative?
We think so. To confirm the data, we did another study of 1,896 university students. We found that, over the preceding two years, left-handed people had had more accidents requiring medical treatment than right-handed people.
Who were more accident-prone, the men or the women?
In a study of 1,000 women and 800 men, the left-handed men were more accident-prone. For the women, 30.6 percent of the righties and 42.7 percent of the lefties had accidents. For the men, 43.6 percent of the righties had accidents vs. 63 percent of the lefties. Most of the men's accidents occurred while playing sports: 36.4 percent for the righties and 39.2 percent for the lefties. The gap between righties and lefties was widest for accidents in vehicles: 7.8 percent of the righties and 16.6 percent of the lefties.
Does left-handedness skip a generation?
No. We've found that if both parents are right-handed, there's a 10 percent likelihood that the offspring will be left-handed. If only the father is left-handed, the likelihood doesn't change; but if only the mother is left-handed, it doubles to 20 percent. If both Mom and Dad are left-handed, there's a 40 percent chance the child will be left-handed also.
Are lefties moodier than righties?
A study in England about four years ago indicated that lefties were more introverted than righties, and there is some indication that left-handers are twice as susceptible to depressive syndromes.
What other differences are there?
We believe that birth trauma, which may contribute to left-handedness, may cause other differences in lefties. Lefties are more likely to have insomnia. They reach puberty maybe four to six months later on average than righties. They are also more likely to have immune-system problems. So they have more allergies and related diseases like Crohn's disease, an inflammatory bowel disease. They tend to be more likely to have juvenile diabetes, dyslexia, retardation, schizophrenia.
Are lefties more creative?
Left-handed people show up in disproportionate numbers in the graphic arts. Among painters, Leonardo da Vinci, Raphael, Hans Holbein, Paul Klee and Picasso were left-handed.
What do you hope your studies achieve? I'm not trying to scare left-handers. We're trying to improve their safety. If, for instance, handedness were included in all accident death records, we could pinpoint the "hot spots" and start to improve conditions for left-handers in vehicles of on the job. In machine shops the left side of power tools is often shoved against the wall. If you simply move the machine out a foot or two, it gives a lefty the same access a right-hander has.