16 | New Scientist | 13 July 2019Climate changeSquishy marbles can
take on many shapesLIQUID marbles have been
developed that can be moulded
into different forms, such as mini
disco balls (pictured below).
Syuji Fujii at the Osaka Institute
of Technology in Japan and his
team were inspired by aphids,
which make liquid marbles by
coating honeydew with wax
particles so that they can easily
transport them.
The team’s lab-made versionsSeals remember,
but not for longSEA lions and seals can recall what
they have just done, and repeat it
on command, if asked to do so
within 18 seconds. This suggests
a degree of awareness.
Simeon Smeele at the
University of Southern Denmark
in Odense and his colleagues
tested seven captive animals:
a grey seal, two harbour seals and
four South American sea lions.
All had previously been trained
to perform actions like waving a
flipper on command. They were
first taught a new command that
meant “repeat what you just did”.
To ensure each animal really
was thinking about what it did
rather than simply recalling the
command for the action, it was
asked to perform a task, then told
to “repeat” it, and then “repeat” it
a second time. At which point just
remembering the previous cue –
“repeat” – wouldn’t help, so itAnimal behaviour^ MaterialsCOWS could be selectively bred to
halve their significant contribution
to global warming.
Livestock are responsible for
14.5 per cent of greenhouse gas
emissions, with the majority
stemming from beef and milk
production, largely because
flatulent, belching cattle emit so
much methane. Researchers have
previously looked at tweaking their
diet to reduce these emissions.
But now there might be another
fix. John Wallace at the University
of Aberdeen, UK, and his colleagues
found that a core group of gut
microbes play a key role in how
much methane a cow emits.
They looked at 1000 cows on
seven farms in Europe over four
years, finding that at least half of
the animals at all the farms had the
same group of 500 gut microbes.Genetic analysis found a small but
abundant number of those microbes
were heritable and played a key role
in determining methane emissions
(Science Advances, doi.org/c7x9).
The team says the microbiome of
herds could be sequenced and those
animals with the heritable, high-
emission microbes selectively bred
out. Eliminating the worst offenders
in the microbiome could halve
livestock emissions, says Wallace.
James Osman of the UK National
Farmers Union says a better
understanding of the genetics of
low-methane livestock, and any
trade-offs with other important
traits, would be needed first.
The proposed breeding would
take decades. A simpler, short-term
idea is a probiotic for young
cattle to alter their microbiome,
says Wallace. Adam VaughanBreeding less gassy cattle
could cut harmful emissions
consist of a droplet surrounded by
small hexagonal plates of a water-
repellent plastic – polyethylene
terephthalate, or PET. They used
liquids such as water and glycerol.
The shape of the marbles
depends on the relative sizes of
droplet and plates. When they are
similar sizes, you get cube-shaped,
tetrahedral or pentahedral
marbles. When the droplets are
larger than the plates, you get
marbles that are nearly spherical,
taking on the form of a disco ball
(Advanced Functional Materials,
doi.org/gfwqc8).
If the marbles are made from
transparent plates, they can be
used as sensors to detect the
presence of gases, says Fujii.
For example, by making the
droplet from liquid that contains
phenolphthalein, the marble’s
colour changes to pink in the
presence of ammonia vapour.
They could also be used to create
different-shaped miniature
chemical reactors used to
catalyse reactions. Donna Lucould only respond to the request
correctly by recalling the action.
All seven animals could do this
(Animal Cognition, doi.org/c7zm).
Smeele says this shows an
awareness of their own behaviour.
That means they have a degree
of consciousness. But it doesn’t
make them as self-aware as we
are, as they would also need to be
aware of their own inner state and
be aware of their own awareness.
To make it even harder, the
team started putting a delay of a
few seconds between the original
action and the repeat command.
The animals became less accurate
with longer delays, and after 18
seconds they were no better than
chance. However, Smeele says
they may remember actions for
longer in more natural settings.
So far, we only know of two
other animals that can remember
their actions: bottlenose dolphins
and monkeys called southern pig-
tailed macaques, which are both
renowned for their intelligence,
unlike seals. Michael MarshallJAZ
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FUJIINews In brief