New Scientist - July 27, 2019

27 July 2019 | New Scientist | 17

Psychology

Animal behaviour Nanotechnology

Parasite brings

down mosquitoes

A 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 movies

Chimpanzees 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 safer

Protecting 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 luck

DO 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 before

and 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. RPS

Mauricio 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 attraction

NOT 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 Crane

Winners 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 Wilson

Scratch used as a stealthy

signal by some great apes

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Really brief

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