Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: MONDAY, April 5, 1993 TAG: 9304050062
SECTION: NATL/INTL PAGE: A1 EDITION: METRO
SOURCE: Los Angeles Times
DATELINE: LOS ANGELES LENGTH: Long
CONVERTED LEFTIES SPIN STATISTICS, DON'T DIE YOUNG
A University of California, Los Angeles, study due next month is likely to help settle the long-simmering dispute over whether left-handed people die earlier than their right-handed counterparts.Contrary to the highly publicized claims that a statistical shortage of elderly left-handers in the population means that left-handers do die earlier, the UCLA study suggests that there is no significant difference in the death rates of the two groups. The researchers found that many older people classified as right-handers were born lefties whose parents and teachers forced them to convert at an early age.
The issue reached new levels of contention two years ago when psychologists Stanley Coren of the University of British Columbia and Diane Halpern of California State University, San Bernardino, reported that left-handers in California's San Bernardino and Riverside counties die an average of eight years prematurely. Their report was met with a hail of criticism and followed closely by a flurry of scientific publications both supporting and rebutting their findings.
None of that evidence has swayed believers on either side of the issue, but the new report may have more credibility because it directly addresses the issue that is at the nub of the controversy:
Why are there so few left-handers among the elderly in the population?
Coren, Halpern and others argue that some left-handers are more susceptible to disease and that all left-handers are susceptible to the risks of using tools, cars and other implements of a modern society designed for right-handers. "Left-handers are being eaten by our environment," Coren said. "They simply don't live as long."
The bulk of scientists, however, have long argued that this apparent lack of old left-handers simply reflects social pressures earlier in this century that caused parents and teachers to force left-handed children to write and eat with their right hands. But there was no proof for this contention - until now.
UCLA psychologist Paul Satz and his colleagues at UCLA and the University of Bergen in Norway took what Satz termed the "rather simple-minded" approach of asking 2,787 people not only which hand they use for a variety of tasks, but also whether they had been forced to switch hands as a child.
Their results, to be reported in the May issue of the journal Neuropsychologia, show that many people, particularly those who are now over 60, say they were indeed forced to switch as children and that this increased proportion in the older groups largely offsets the decline in incidence of left-handers.
A typical written comment from one of the respondents, an 86-year-old man, noted, "Went to school in the days when they whacked your duke if left-handed, so ended up a pseudo right-hander." Another woman, age 82, wrote: "I was born left-handed, in those days they switched everybody to right."
"The left-handers are still present in older populations," Satz concluded. "They simply show up on most surveys as right-handers."
"This is a very important paper," said psychologist Loren Harris of Michigan State University. "I don't think it will put an end to the controversy, but it should."
Coren, shown the UCLA report, argues that hand-switching does not account for all the loss of left-handers with increasing age. Satz's figures still show a small trend toward fewer left-handers in the older populations, but it now seems clear, other experts said, that the risk to left-handers is substantially smaller than Coren and Halpern have argued.
The extent of that risk is of more than academic interest. If Coren and others are right, insurance companies might set higher rates for left-handers in the same way that they now set higher rates for men because they die earlier than women. Factories and many hand tools might have to be redesigned to prevent product liability suits.
Perhaps most important, Satz said, parents might once more begin forcing their left-handed children to use their right hands. "This issue has terrified some parents," he said. In light of his new results, however, the message is clear, he said: "Parents should let children develop naturally . . . Biology is so important. Don't tamper with it."
In the population at large, about 9 percent of women and 13 percent of men are left-handed, but many studies have shown a peculiar age distribution. At the age of 10, 15 percent of the population is left-handed. At 20, 13 percent. By age 50, the proportion drops to 5 percent, and beyond age 80, it is less than 1 percent.
Scientists are not completely sure why left-handedness develops. Perhaps as much as half the time, it is simply genetic - although no one has ever convincingly argued which genes are responsible.
But the other 50 percent of left-handedness, many researchers argue, is caused by trauma in the womb or at birth. Recent studies have shown, for example, that children of mothers who smoke, children who were resuscitated after birth and children who were twins or triplets are all significantly more likely to be left-handed. Other studies have associated it with prolonged labor, breech birth, prematurity, low birth weight and Rh incompatibility between the mother and fetus.
Individuals with this pathological left-handedness are more prone to a variety of problems, including neuroticism, allergies, insomnia, learning disorders, migraines, immune disorders and, according to at least two recent studies, homosexuality.