New Scientist - USA (2021-02-27)

27 February 2021 | New Scientist | 19

Psychology

Public health Bionics

‘Nudges’ can lead to

healthier shopping

In a small trial in the UK,

28 per cent of online food

shoppers were willing to

buy a healthier version of

a product when presented

with the choice. Accepted

swaps reduced calorie

content in the average

shopping basket by

around 30 kcals, showing

the power of “nudging”

(PLoS One, doi.org/fwb3).

Dogs playing fetch

may be body aware

Dogs seem to be conscious

of their bodies. When asked

to retrieve a toy that was

attached to a mat on

which they were sitting,

eight out of 10 dogs

stepped off the mat –

recognising their bodies

were in the way. Just half

of dogs left the mat if the

toy was attached to the

floor instead (Scientific

Reports, doi.org/fwp2).

Our activity harms

life in many rivers

Fish biodiversity in

some 53 per cent of river

basins around the world

has been severely affected

by human activity, with

Europe and North America

worst hit. As well as

overfishing, dams are

a problem because

they block migrating fish

(Science, doi.org/gh4jbr).

Shaping someone’s

dream as it happens

TALKING to people while they are

asleep can influence their dreams,

and in some cases the dreamer can

respond without waking up.

Ken Paller at Northwestern

University in Illinois and his team

found that people could answer

questions and even solve maths

problems while lucid dreaming –

a state in which the dreamer is

aware of being in a dream and

is sometimes able to control it.

The researchers asked dreamers

NATURE sanitises around 38 million

tonnes of human waste a year – the

equivalent of around £3.2 billion

of commercial water treatment.

Alison Parker at Cranfield

University in the UK and her team

looked at 48 cities in Africa, Asia,

North America and South America.

They analysed how much human

waste is produced and where it

ends up by reviewing existing data.

They looked at waste systems not

connected to sewers. This included

pit latrines (pictured) and septic

tanks, in which waste is primarily

contained on-site below ground.

Liquid waste from pit latrines and

excess water from septic tanks can

gradually filter through soil. In

areas where groundwater isn’t too

shallow, this can remove the waste.

With 892 million people, mainly in

low and middle-income countries,

using this type of waste system, the

team estimates that nature safely

treats around 38 million tonnes of

human waste per year (Cell Press:

One Earth, doi.org/fwpv).

More than 4 billion people don’t

have access to safe sanitation, a

third of them in low-income nations.

Unsafe sanitation is responsible for

775,000 deaths a year. “Sanitation

that involves the ground naturally

treating waste can be part of the

solution,” says Parker. Priti Parikh

yes-no questions relating to their

backgrounds and experiences,

along with some simple maths

problems. The dreamers weren’t

aware of the questions they would

be asked before they went to sleep.

They answered the questions

correctly 29 times, incorrectly five

times and ambiguously 28 times,

by twitching their face muscles

or moving their eyes. They didn’t

respond on 96 occasions.

After waking, some dreamers

reported hearing the questions as

if from outside the dream, while

others perceived them as being

part of the dream. One participant

Robo muscles that

are more like ours

OUR muscles get stronger when

put under stress and now robots

could do the same, thanks to a

soft gel that becomes harder

when exposed to vibration.

Zhao Wang at the University

of Chicago and his team created

the gel by embedding zinc oxide

nanoparticles into a cellulose

mixture. They then vibrated

the material and found that the

nanoparticles emitted an electrical

charge that created new links

within the gel, toughening it.

The team found the strength of

the gel increased as it was shaken.

The strengthened gel maintained

its shape when squashed with a

press, but the untreated material

was deformed permanently,

demonstrating that the gel had

become up to 66 times stiffer from

the vibrations (Nature Materials,

DOI: 10.1038/s41563-021-00932-5).

The team now aims to make

the process reversible by trying

to create bonds in the gel that

will decay over time. The material

could then have a range of

applications such as artificial

robotic muscle that adapts to

tasks and becomes stronger at

performing repetitive motions,

but could also lose strength and

gain flexibility to better suit a new

task, says Wang. Matthew Sparkes

who was dreaming about being

in a car heard maths problems

coming from the radio (Current

Biology, doi.org/fwck).

“One thing that this method

puts forward is that while the

dream is happening, we can affect

the content,” says Mark Blagrove

at Swansea University, UK. In the

future, Paller hopes that this could

help improve sleep in people with

conditions like anxiety. “If you’re

facing something that makes you

anxious, you might want to try it

out in a lucid dream and therefore

overcome the anxiety that you’re

feeling,” he says. Krista Charles

Soil deals with massive

amount of human waste

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Really brief

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