http://health.msn.com/dietfitness/articlepage.aspx?cp-documentid=100159952>1=10008
Do Right-Handed People Live Longer?
Expert answers to this and other questions from curious readers.
By Scott McCredie for MSN Health & Fitness
There’s always been something sinister about being left-handed. But
shorter life spans? That’s downright creepy. The notion apparently
sprang from a Canadian psychologist named Stanley Coren, who declared in
his 1992 book, The Left-Handed Syndrome, that left-handers, on average,
lived about a decade less than right-handers do.
For the previous decade, Coren and others who study “handedness” in the
population (90 percent are right-handed, with twice as many lefties
among men than women) had amassed data that seemed to show that as the
population aged, the percentage of lefties kept decreasing.
What could be killing off the lefties so virulently? Lots of hypotheses
arose. The dangers of operating machines and equipment designed for
right handers. A developmental or pathological irregularity. A greater
desire to take risks. Nobody knew.
Until 1993. In that year scientists at the National Institutes of Health
and Harvard University co-authored a study published in the American
Journal of Public Health. They examined the death reports of nearly
4,000 Bostonians over the age of 65. Critically, each report contained
accurate information about hand dominance, gathered for a separate
study. The result? Over six years, the death rate for righties was 32.2
percent, for lefties 33.8 percent, a statistically insignificant
difference.
Dr. Marcel Salive, one of the co-authors, said he thought data from
previous studies had been misinterpreted. “As a consequence of that
interpretation,” he told The New York Times, “a lot of people had
unwarranted fears.”
So take heart, lefties. Even though the misinformation persists, you
weren’t handed a mortal curse at birth.
Is it true people use only 10 percent of their brains?
Among the most popular science myths, this one has been around for more
than a century. Nobody knows how it got started, but it’s certainly been
a useful motivational tool for generations of nagging parents (“Billy,
just think what you could make of yourself if you tried using the other
90 percent!”), advertisers who hint that if we use their products we
must be pretty smart cookies, and psychics who claim their powers come
from the untapped portion.
Along the way, dozens of prominent scientists—including Albert Einstein,
William James and Margaret Mead—have helped preserve the adage. While
these folks were highly qualified in their fields, none was a
neuroscientist.
“If it were the case that we used only 10 percent of our brain,” says
Professor Reza Shadmehr, a neuroscientist at Johns Hopkins University
School of Medicine, “then damage to a small part should have little
impact on our abilities. We know from studies of stroke patients that
when a small portion of the brain is damaged, there are often
devastating consequences.”
“Even while you sleep, the brain is quite active, particularly during
rapid eye movement [REM] sleep when dreaming occurs,” says Dr. Sterling
Johnson, assistant professor of medicine at the University of Wisconsin
School of Medicine and Public Health. “In this stage of sleep, the
brain’s electrical activity is the same as in your normal wakeful
state.”
Besides clinical observations, brain scans (both PET and MRI) also
provide evidence that many places in the brain are active during a
variety of tasks, according to Dr. Eric Chudler, a neuroscientist at the
University of Washington in Seattle.
“It appears that there is no hidden storehouse of untapped brain power,”
Chudler notes. “We use all of our brain.”
How long after the expiration date is it safe to drink milk?
The date you see on milk cartons isn’t an expiration date. In other
words, the milk doesn’t necessarily go bad the next day. The date is
placed there “to let stores know when to pull products from the shelf to
maintain top quality,” according to Judy Simon, a nutritionist with the
University of Washington Medical Center. “You can still safely drink
milk three to seven days after the date if the milk has been stored
properly.”
That means keeping milk in a refrigerator at 40 degrees or below, and
not letting it sit on the counter for long periods. If milk isn’t
handled properly, it can turn sour even before the “sell by” date.
Fortunately, when it does you can use your nose, tongue and eyes to
tell. It will smell bad, taste sour and may start to thicken. That’s
when it’s time to pour it down the drain.
In some parts of the country, you may have to rely completely on your
senses (or on your grocer’s memory) to tell you that milk is drinkable,
because no uniform system for food dating exists in the United States,
according to a report issued by the U.S. Department of Agriculture.
“Although dating of some foods is required by more than 20 states, there
are areas of the country where much of the food supply has some type of
open date and other areas where almost no food is dated,” the report
states.
So read the date on the carton (if it has one), but rely on your senses.
Is chewing ice bad for your teeth?
Though millions of people do it every day, and no studies have been done
on its effects, chewing ice doesn’t get the American Dental Association
Seal of Approval. Dr. Barbara Rich, a spokeswoman for the Academy of
General Dentistry, says people should avoid chewing ice, popcorn kernels
and opening nuts with their teeth. Anything that hard could lead to
chipping and breakage of natural teeth and restorations.
Some people routinely chew ice, and this can be especially harmful,
according to Dr. Tar-Chee Aw, associate professor at the University of
Washington Department of Restorative Dentistry. “The habit can lead to
gum injuries and fractured teeth,” he says. “Normal wear and tear is
speeded up, and failure of restorations is accelerated due to the
continuous stress, strain and repeated impact on teeth.”
Aw says compulsive and repeated chewing of ice, known as pagophagia, “is
most commonly linked to iron-deficiency anemia, more common in women.
Among the symptoms of iron deficiency is an inflammation or soreness of
the tongue, which may intuitively lead to ingestion of ice for relief.
It can also be caused by an underlying medical condition, such as a
developmental disorder like autism, or a psychological disorder like
obsessive-compulsive disorder (OCD) or psychiatric illness like
schizophrenia, or even simply emotional stress. In this case,
pharmacologic and/or cognitive behavior therapy may be recommended.”
--
Atheist n A person to be pitied in that he is
unable to believe things for which there is
no evidence, and who has thus deprived himself of
a convenient means of feeling superior to others.
—Chaz Bufe, The American Heretic’s Dictionary
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