مرکزی صفحہ New Scientist Wildlife retreats to the dark of night

Wildlife retreats to the dark of night

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جلد:
238
زبان:
english
رسالہ:
New Scientist
DOI:
10.1016/S0262-4079(18)31095-9
Date:
June, 2018
فائل:
PDF, 838 KB
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NEWS & TECHNOLOGY

BENCE MATE/NATUREPL.COM

Magnets can
make bad wine
taste better

Wildlife retreats to
the dark of night
Michael Le Page

in Sumatra, Indonesia, 90 per cent
of activity is at night. Similarly, in
protected areas of Tanzania, only 17
per cent of lion activity is at night.
Outside them, it is 80 per cent.
On average, animals with a
50/50 split between night and
day activity in undisturbed areas
have a 70/30 split in disturbed
areas (Science, doi.org/gdm9ht).
“There are fewer and fewer
spaces wildlife can go to avoid

ONCE great monsters ruled Earth
and mammals came out only at
night. Now many mammals are
reverting to the nocturnal habits of
their distant ancestors as fearsome
creatures once again reign.
“Dinosaurs were the ubiquitous
terrifying force on the planet,”
says Kaitlyn Gaynor at the
University of California, Berkeley.
“Now humans are the ubiquitous
“It’s a way to share space
terrifying force on the planet
on an increasingly crowded
and we’re forcing all of the other
planet. We take the day
mammals back into the night.”
and they take the night”
Gaynor and her colleagues
noticed animals were becoming
more active at night to avoid
people,” says Gaynor. “So they’re
human disturbances. They have
avoiding us in time because they
now done a meta-analysis of
can’t avoid us in space.”
76 studies of 62 mammals all
And it is not just happening
around the world. Almost all are
in places like cities with lots of
shifting to the night to avoid us.
people. It is also occurring near
Take the now ironically named
roads, rural settlements and
sun bear from South-East Asia. In
even hiking areas.
areas with few people, only 19 per
It is unclear what the
cent of sun bear activity occurs at
consequences are.
night. But around a research camp
On the one hand, animals
14 | NewScientist | 23 June 2018

Human disturbance is pushing
more mammals to be nocturnal

forced to do more at night might
struggle compared with those in
undisturbed areas. For instance,
sable antelope in Africa usually
avoid waterho; les at night because
predators like lions might be lying
in wait. But in areas of Zimbabwe
where sports hunters lurk near
waterholes by day, they drink at
night. Overall, more may be killed.
On the other hand, the shift is
helping animals survive alongside
humans. In Chitwan in Nepal, lots
of tigers are able to live near people
by being more active at night.
In this sense, the shift to the night
may be good. “It’s a way to share
space on an increasingly crowded
planet,” says Gaynor. “We take
the day and they take the night.”
Thanks to their nocturnal
ancestors, many mammals still
have plenty of the characteristics
needed to be more active at night,
she says. And they are likely to be
evolving to be even better at it.
“I would expect that this is an
incredibly strong selective force,”
says Kate Jones of University
College London, who has shown
that mammals only became
active during the daytime after
dinosaurs vanished. ■

WINE’S complex flavour is the result
of a delicate balance of fruity, floral,
earthy, sweet and other aromas.
Yet if one is too strong, it can ruin the
overall taste. The solution? Magnets.
Cabernet Sauvignon and Sauvignon
Blanc often contain a green bell
pepper flavour that gives subtle
character in moderation but tastes
strange in excess. It is most pungent
in grapes that are picked early or
grown in cool climates.
David Jeffery at the University of
Adelaide, Australia, and his colleagues
found a way to remove excess
amounts of this flavour from Cabernet
Sauvignon by treating it with tiny
magnetic beads.
The nanosized iron beads were
coated in plastic molecules designed
to attract the bell pepper-tasting
chemical. The team stirred the beads
through the wine for 2 hours to mop
up the chemical, then removed them
using an ordinary magnet.
Chemical analysis revealed that
the magnetic treatment eliminated
74 per cent of the green bell pepper
flavour. A blind taste test by a panel
of eight people confirmed that the
treated wine no longer had the
unpleasant aroma.
The beads partially removed some
of the wine’s fruity chemicals as well,
but the difference wasn’t significant
enough for the taste-testers to
detect. They rated the treated wine as
having the same fruity character and
overall aroma intensity as the original
wine (Journal of Agricultural and Food
Chemistry, doi.org/cq36).
The magnetic treatment is a major
improvement over existing methods
for improving wine, says Jeffery.
At the moment, wine-makers typically
blend batches with strong bell pepper
notes with lighter ones in an effort to
balance out the taste, or add activated
charcoal or oak chips to remove the
overpowering flavour. However, these
additives tend to “rip out lots of the
other flavours as well”, says Jeffery.
Alice Klein ■