27 July 2019 | New Scientist | 17PsychologyAnimal behaviour NanotechnologyParasite brings
down mosquitoesA bacterial parasite that
hampers fertility in Asian
tiger mosquitoes (Aedes
albopictus) has been used
to reduce the number of
biting female insects by
more than 80 per cent
at two sites in Guangzhou,
China (Nature, doi.org/
c8kg). Similar approaches
have been tried elsewhere
before, but are yet to be
used on a large scale.Chimps bond after
watching moviesChimpanzees who watch
a short film with a human
or another chimp are more
likely to then approach that
individual or spend time
near them, a study has
found. This suggests chimps
feel closer to those they
have shared an experience
with, just like we do
(Proceedings of the Royal
Society B, doi.org/c8j6).Drones can keep
white rhinos saferProtecting southern white
rhinos from poachers in
South Africa is costly, so
could cheap drones be the
answer? Researchers found
that drones can be used
to scare rhinos away from
poaching hotspots, such
as near buildings and roads
(Proceedings of the Royal
Society B, doi.org/c8kb).Money influences
our view of luckDO PEOPLE owe their wealth to
skill or luck? Your views on this
may be set by your own financial
gains, at least according to a study
of people playing a card game.
In a simplified two-player
version of card game President
involving cash prizes, winners
were more likely than losers to
credit skill not luck. This was the
case even though it was clear the
game involved little skill and the
odds were rigged in their favour.ORANGUTAN mothers use loud
scratches to tell their infants that it
is time to leave an area and move to
another, possibly to avoid attracting
predators or other orangutans.
Marlen Fröhlich at the University
of Zurich in Switzerland and her
colleagues noticed wild Sumatran
orangutans in the Suaq Balimbing
forest in Sumatra, Indonesia, would
sometimes scratch themselves
in a loud and exaggerated way.
Fröhlich and her team analysed
1457 bouts of scratching produced
by 17 different orangutans,
including four mothers and their
dependent offspring. They noted
the behaviour that occurred beforeand after each of these occasions.
Exaggerated scratches were
overwhelmingly produced by
mothers shortly before moving.
They were usually directed towards
a dependent offspring who was
paying attention to them and who
responded by moving towards the
mother, says Fröhlich.
As a result, these loud scratches
could be distinguished from normal
scratches and appear to be used to
tell infants that it is time to leave
(Biology Letters, doi.org/c8jj).
Fröhlich says that looking at
other orangutans may reveal
whether this is evolved behaviour
or culturally learned. RPSMauricio Bucca of the European
University Institute in Florence,
Italy, recruited about 1000 people
to play through a website, giving
people $2.50 for taking part and a
$5 bonus if they won.
Whoever was randomly picked
to play the first card in round one
always had an advantage that
meant they were most likely to win
that round. In some versions, this
advantage was boosted in round
two. In other versions, the opposite
happened: the round one loser
was given an unfair advantage.
At the end of their game, people
were asked if it had been fair.A liquid magnet that
keeps its attractionNOT all magnets have to be solids:
a type of liquid magnet has been
developed that may eventually
help control wireless soft robots.
Liquid magnets of a sort already
exist, called ferrofluids. These are a
mixture of a non-magnetic liquid
and solid magnetic nanoparticles.
However, they act like magnets
only when under the influence of
an external magnetic field. Now
Thomas Russell at the University
of Massachusetts, Amherst, and
his colleagues have been able to
turn a ferrofluid into a fluid that
retains its magnetic properties.
They did this using magnetic
nanoparticles containing iron
oxide. When those particles float
freely in liquid hydrocarbon, they
create a ferrofluid. The researchers
found that when there are enough
particles to cover the surface
of a droplet and jam together,
the droplet stays magnetic.
The interior remains liquid.
When exposed to magnetic
fields, the droplets could move
around or change shape, and if the
magnetic field rotated, the drops
spun too. This means they could
eventually be used to move parts
of soft robots. That would require
an external magnetic field, but no
wires or internal batteries (Science,
doi.org/c8jv). Leah CraneWinners of the bonus were more
likely to say yes than losers.
Even when the winners benefited
from receiving either one or two
strong cards from their opponent,
they were twice as likely to judge
it a fair game as the losers.
What is more, in most versions
of the game, winners were more
likely than losers to attribute
success in the game to talent
(Science Advances, doi.org/c8js).
The phenomenon is probably
even stronger in real life because
we are more likely to be influenced
by personal circumstances, says
Bucca. Clare WilsonScratch used as a stealthy
signal by some great apes
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UAQ^ PROJECTReally brief
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