bilingual babies discern languages
early challenge of learning two tongues may hone thinking
by bruce bower
Babies living in bilingual homes get a perceptual boost by 8 months of age that may
set the stage for more resilient thinking
later on, scientists reported February 18.
Infants raised bilingual from birth can
distinguish not only bet ween their native
tongues but between languages they’ve
never encountered, even when they see
adults speak without hearing what they
say, said psychologist Janet Werker of
the University of British Columbia in
Vancouver. Babies in monolingual households lack these discrimination skills,
Werker and her colleagues have found.
Given exposure to two tongues, infants
develop an ability to track closely what
they hear and see to decode languages,
Werker proposed. In the visual realm,
such information may include lip move-
ments, the rhythm of the jaw opening and
closing, and other facial movements.
by susan milius
There’s something as yet unknown going
on with black bear hibernation that
slows metabolic rates more than lower
body temperatures alone
In the depths of Alaskan
winters, closely monitored
black bears dropped their
temperatures only a modest
5. 5 degrees Celsius on average. A standard physiological calculation predicts
that such a chill would slow
metabolism to 65 percent of
nonhibernating resting rates.
But the bears’ metabolisms
plunged down to even more energy-saving
zones, averaging only 25 percent of the
basic summer rate, ecological physiologist
Øivind Tøien of the University of Alaska
Fairbanks and colleagues reported
February 17 and in the Feb. 18 Science.
Such a major disconnect hasn’t shown
up in research on any other hibernating
mammal, said study coauthor Brian M.
Barnes, also of UA Fairbanks.
The study is the first to manage continuous monitoring of metabolic rate
and body temperature throughout bear
hibernation with little disturbance of the
animals, Tøien said. Other studies based
on intermittent sampling
with older instruments,
indirect evidence or studying bears with lots of people
nearby have left the matter
“uncertain,” as he put it.
The researchers monitored five bears, setting
the animals up in wooden
den boxes in an enclosure
deep in the woods. The
boxes were rigged to allow
a bear to break out anytime
it wanted. While the bears were inside,
researchers measured metabolic rate,
muscle movement and heart function.
drops in hibernating
bears belie a major
bears slow way
down in winter
Ursine hibernation turns out
to be deeper than expected
Reports of large drops in bear metabolic rates during hibernation cheer Eric
Hellgren of Southern Illinois University
Carbondale, who admits to “a biased
viewpoint as a bear biologist.” He said
the Alaska study may lay to rest some of
the long-running discussions from physiologists who treat bear hibernation as “a
different and ‘lesser’ form” compared
with the big metabolic shifts seen in small
animals such as ground squirrels.
Heart rate tracking for three of the
Alaska bears showed a drop from 55
steady beats per minute on average before
hibernation to 14 erratic beats per minute
in winter. Physiological ecologist Hank
Harlow of the University of Wyoming in
Laramie said that he too has listened to
hibernating bear hearts going still for a
stretch and then kerthumping arrhythmically. Maybe it saves energy, he said.
The Alaska team also found that
when bears got moving again in spring,
their metabolisms took several weeks
to creep back to normal. Monitoring
data showed that bears with half-speed
metabolic rates still display normal
bearish behavior, however.
Ø. TØien/Univ. of alaSka fairbankS