22 August 2020 | New Scientist | 19Technology Biology
Chris Stokel-Walker Jo Marchant
NUISANCE phone calls could
disappear with the help of a virtual
assistant that screens spammers
before the phone even rings.
Robocalls, in which an automated
recording pretends to be a human,
are a common problem – there are
an estimated 4.9 million every hour
in the US alone. Simple block lists
can screen some of these out, but
they are only around 60 per cent
effective, says Sharbani Pandit at
the Georgia Institute of Technology.
In an attempt to do better, Pandit
and her colleagues have created a
virtual assistant that acts as a buffer
between the caller and the recipient.
If a number isn’t in a phone’s contact
list, the call-maker is diverted to
the assistant and asked to state the
recipient’s name. “A person who
knows my name is calling with a
good intention – or they’re not
typical robocallers,” says Pandit.
If the caller responds, the virtual
assistant interrupts them, saying:
“Sorry, I didn’t get that. Can you
please say who you are trying to
reach again?” While a robocaller
probably won’t notice the question,
a human is likely to stop talking. If
they do, the virtual assistant passes
on the call via an app, along with
a transcribed name.
When tested on around
8000 recorded robocalls, the
system blocked every single one.
A further test with 21 human
participants, in which the callers
engaged with the virtual assistant
but occasionally used the wrong
name, was 97.8 per cent effective
(arxiv.org/abs/2008.03554).
“It’s like a spam filter that
checks that the sender has at
least minimal knowledge about
the addressee and is flexible
enough to produce that knowledge
on request,” says David Schlangen
at the University of Potsdam,
Germany. He says the system
could be circumvented but that call
spammers are unlikely to bother. ❚
Virtual assistant
may put an end to
annoying robocalls
A DOSE of radio waves seems
to encourage plant seedlings
to grow faster. If confirmed,
the find could have applications
from farming to medicine.
Margaret Ahmad at Sorbonne
University in Paris, France, and
her colleagues exposed thale
cress seedlings (Arabidopsis
thaliana) to weak pulses of
radio frequency (RF) radiation
at 7 megahertz, a frequency used
by amateur radio operators.
The team found that this
altered the activity of a type of
light sensor in the plants calleda cryptochrome. The expression
of several genes regulated by
the sensor also changed, and the
seedlings grew slightly faster.
This is the first time anyone
has found a biological receptor
sensitive to radio waves, says
Ahmad. “What we showed is
that we can manipulate the
chemistry of the cryptochrome
receptor in living plants by a
remote radio frequency signal.”
Cryptochromes are proteins
found across biology in insects,
birds and mammals, including
humans. They have many
functions, from regulating plant
growth rates and biological
clocks to helping birds navigate.
They are thought to sense
weak magnetic fields in many
species, through a quantum
mechanism in which the field
alters the rate at which the
protein is activated by light.
Ahmad, who discovered
cryptochromes in the 1980s,
wondered if these receptors
might also be sensitive to radio
waves. Extremely weak RF
radiation is known to disruptmagnetosensing in birds,
insects and rodents, but the
mechanism is unknown.
The team predicted that if
the quantum cryptochrome
theory is correct, RF radiation
should also interfere with the
cryptochrome sensor, blocking
the effect of Earth’s magnetic
field. This is indeed what they
found, with the seedlings in
RF radiation responding in the
same way as young plants in a
null magnetic field (Scientific
Reports, doi.org/d6mz).
The result strengthens
the idea that human-made
electromagnetic noise can have
biological effects. The signals
used by Ahmad’s team were
about 10 times higher than
the radiation emitted by
radio transmissions or
electrical appliances in a home,
but she says the behaviour
of birds and insects can be
affected by far lower intensities.
Alfonso Balmori, a biologist in
Valladolid, Spain, says this adds
to evidence for biological effects
that aren’t currently considered
in health and safety standardsfor telecommunications
networks. There is still lots
we don’t know, he says,
“so we should always apply
the precautionary principle”.
David Keays at the Research
Institute of Molecular
Pathology in Vienna, Austria,
says the effect is interesting,
but needs to be replicated.
He says any effect on wildlife
is likely to be small. Birds use
several different methods to
orientate themselves, he says,
including visual cues, so can
probably work around any
electromagnetic noise.
“My suspicion is that climate
change and light pollution have
a much larger impact,” he says.
He also emphasises that the
research in no way supports
conspiracy theories relating
to 5G cellular networks
spreading the coronavirus.
Cryptochrome reactions
produce potentially toxic
chemicals called reactive
oxygen species. These can
be harmful at high levels, but
at smaller doses, they activate
cellular repair and stress
response mechanisms.
Ahmad suspects that
organisms would quickly adapt
to low-level, continuous RF
radiation in the environment.
But she believes short, tailored
pulses of radio waves could
prove useful. Farmers might
use radio masts to trigger stress
responses in crops, making
them more robust against
drought or pests, she says.
In medicine, she says, RF pulses
might help to trigger repair
mechanisms in specific tissues.
“The potential for therapy
is very real,” she says.
Keays, however, says
he doesn’t think the effects
could ever be large enough
to be useful. ❚Radio waves boost
the growth of plants
PIERR
E^ BRYE/ALAMYThe growth of thale cress
can be affected by radio
frequency radiation“This is the first time
anyone has found a
biological receptor
sensitive to radio waves”