Health & Science NEWS 21
Heat that’s really off the charts
In as little as two decades, climate change
will likely result in millions of people in the
U.S. experiencing heat so extreme that it will
be literally off the chart. That’s the conclu-
sion of the Union of Concerned Scientists, a
nonprofit that conducted a county-level esti-
mate of how often the “heat index”—which
combines temperature and humidity—will
surpass 100 degrees Fahrenheit. The heat
index is a useful measure of when heat
becomes dangerous: At 104 degrees, the
human body starts to heat up to the ambient
temperature. The researchers concluded that
the number of 100 degree–plus days will
more than double nationally by midcentury;
about 250 U.S. cities will endure a month
or more of these days a year, compared
with just 29 cities historically. In parts of the
Southeast, the Southern Great Plains, and
the Midwest, temperatures will go beyond
the heat index’s upper limit of 127 degrees.
“We have little to no experience with ‘off-
the-charts’ heat in the U.S.,” co-author Erika
Spanger-Siegfried tells NationalGeographic
.com. “Exposure to conditions in that range
makes it difficult for human bodies to cool
themselves, and could be deadly.”Small calorie cuts, big benefits
Consuming just 300 fewer calories a
day—the amount in a large bagel or a fewchocolate chip cookies—can have big health
benefits, reports The New York Times. In a
new study, scientists observed 143 healthy
men and women, ages 21 to 50, who tried
to cut their daily calorie intake by 25 per-
cent for two years. Many of them fell short,
managing only a 12 percent reduction on
average—about 300 calories. Yet the health
gains from that small cut were significant.
Participants lost weight and body fat; their
blood pressure dropped; their cholesterol
levels and blood sugar control improved;
and they had less inflammation. While some
of the benefits clearly resulted from the par-
ticipants’ weight loss, the extent of the meta-
bolic improvement suggested that the calorie
reduction itself had some effect, too. “We
weren’t surprised that there were changes,”
says study leader William Kraus, from Duke
University. “But the magnitude was rather
astounding. In a disease population, there
aren’t five drugs in combination that would
cause this aggregate of an improvement.”Humans’ early exit from Africa
A new analysis of two skull fragments
found in a cave in southern Greece suggests
that early humans may have first left Africa
far earlier than previously thought. Until
now, the oldest Homo sapiens fossil dis-
covered outside Africa was a 180,000-year-
old jawbone unearthed in Israel.
Scientists think it came from
one of many early human
groups that tried—and
ultimately failed—to
settle away from Africa;
it wasn’t until 50,000
years ago that our
ancestors successfully
relocated. The skull
fragments in Greece
were first discovered
in the 1970s and were
initially thought to belong
to Neanderthals, who arrivedin Europe some 400,000 years ago. But
by analyzing tiny amounts of uranium in
the fossils and using computers to create
a 3D image of what the complete skulls
would have looked like, scientists concluded
that while one of the fossils was from a
170,000-year-old Neanderthal, the other
was a 210,000-year-old Homo sapiens.
If confirmed, that would make it the old-
est modern human fossil found anywhere
outside Africa. Lead author Katerina
Harvati, from the University of Tübingen in
Germany, tells TheGuardian.com that the
discovery confirms that humans didn’t leave
Africa in “one major exodus.”Health scare of the week
Fruit juice and cancer
Drinking lots of sugar-sweetened drinks
and fruit juice may increase your risk for
cancer, according to a new French study.
Researchers examined nine years’ worth of
data from a long-running study in which
some 101,000 healthy adults, average age
42, completed numerous surveys about
what food and drink they had consumed
the previous day. After controlling for risk
factors such as family health history and
physical activity levels, they found that
drinking just 3.4 fluid ounces of sugary
beverages a day—about a third of a typical
can of soda—was linked with an 18 per-
cent increase in overall cancer risk and a
22 percent higher risk for breast can-
cer. The increase was the same for
fruit juice and sodas; there was no
link for artificially sweetened drinks.
Study leader Mathilde Touvier cau-
tions that the findings show cor-
relation, not causation. But she says
one explanation for the connec-
tion may be sugar’s link to obesity.
“High sugary drinks consumption
is a risk factor for obesity and weight
gain,” she tells CNN.com, and “obesityGet is in itself a risk factor for cancer.”
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AP
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Leading a healthy lifestyle may reduce
risk for dementia, even among people
genetically predisposed to the condition,
new research suggests. British scientists
examined nearly 200,000 people, all age
60 or older and with no signs or symp-
toms of dementia at the start of the study.
Participants were each given a “polygenic
risk score” that estimated their genetic
risk for dementia, and a “healthy lifestyle
score” factoring in things like alcohol
consumption and exercise. Study subjects
were tracked for about eight years, during
which those with the worst lifestyle score
and the highest genetic risk were threetimes more likely to develop dementia
than the healthiest participants with the
lowest genetic risk. But among those with
high-risk genes, participants who led a
healthy lifestyle—eating well and exercis-
ing regularly, for example—were 32 per-
cent less likely to develop dementia than
those with bad habits. Researchers say
the study should give hope to people who
are told they are genetically predisposed
to dementia. It “undermines a fatalistic
view of dementia,” senior author David
Llewellyn, from the University of Exeter in
England, tells ScienceDaily.com. “Some
people believe it’s inevitable they’ll develop[the condition] because of their genetics.
However, it appears that you may be able
to substantially reduce your dementia risk
by living a healthy lifestyle.”Healthy living can counteract dementia risk
Sweltering in Los Angeles: The new normal?Getting fit is good for your body and brain.