6 February 2021 | New Scientist | 19EvolutionMole rat groups chirp
in their own accentCOLONIES of naked mole rats
develop dialects that may help
them tell friends from foes.
These rodents (Heterocephalus
glaber) are extremely vocal. To see
whether their vocalisations help
maintain their social structure,
Alison Barker at the Max Delbrück
Center for Molecular Medicine in
Germany and her team recorded
more than 36,000 greeting calls
from 166 naked mole rats inSpeaker’s hands
influence listenersMAKING simple up and down
hand movements while speaking
may affect the way people hear
what you are saying.
We often use meaningless
movements, such as flicking or
waving our hands, known as beat
gestures when speaking face to
face. These typically align with
prominent words in speech.
“Politicians use these gestures
all the time to get their message
across,” says Hans Rutger Bosker
at the Max Planck Institute for
Psycholinguistics in Nijmegen
in the Netherlands.
Bosker and his team tested how
important these movements are
in influencing sound recognition.
They presented Dutch participants
with video of Bosker saying Dutch
words that have two meanings
depending on which syllables are
stressed. Bosker paired each word
with a beat gesture either on theBody language^ Animal behaviourFLOWERING plants may have
evolved 250 million years ago, more
than 100 million years earlier than
the oldest known fossil flowers.
Today, flowering plants – or
angiosperms – are the most diverse
group of land plants. The oldest
angiosperm fossils so far found date
to 135 million years ago in the early
Cretaceous. Many researchers think
this is when the group arose. The
fossil record suggests the group was
diverse by 130 million years ago.
But how they became so diverse
so fast has perplexed scientists.
The fossil record and genetics offer
conflicting evidence, with the latter
pointing to a much older origin.
To create a more accurate
timeline, Daniele Silvestro at the
University of Fribourg, Switzerland,
and his team analysed more than
15,000 fossils from around 200different angiosperm families.
The result was strong evidence
angiosperms may have arisen up to
250 million years ago, long before
the Cretaceous. This is because if a
number of related fossils all appear
between 135 and 130 million years
ago, they must have evolved from a
much earlier common ancestor not
in the fossil record (Nature Ecology
& Evolution, doi.org/fsjk).
If the team’s estimate is right,
angiosperms spent their first
100 million years on Earth as
rare components of ecosystems
that were unlikely to fossilise.
While Patrick Herendeen at
the Chicago Botanic Gardens is
sceptical of the findings, he says he
wouldn’t be surprised if angiosperm
fossils from before the Cretaceous
are discovered in the future.
Ibrahim SawalFirst flowers may have
been early bloomers
seven colonies raised in labs.
After identifying the acoustic
features of these soft chirps,
such as pitch, peak frequency
and duration, the researchers
used the calls to train a machine-
learning algorithm.
Not only could the algorithm
reliably recognise individuals
within a colony, but the chirps’
features were also highly
predictive of which colony
an animal belonged to, akin to
human accents or dialects. This
suggests that individuals from
each colony have unique voices
while all sharing the same dialect.
In another test, naked mole rats
responded far more frequently to
recordings of their own dialect
than to other dialects, suggesting
they use call and response when
identifying colony members.
Barker and her team also
found that three abandoned
pups placed with new colonies
developed the dialect of their
adoptive homes (Science,
doi.org/fsjh). Bethan Ackerleyfirst syllable or the second syllable.
The team found that
participants were on average
20 per cent more likely to hear
stress on a syllable if there was a
beat gesture on it. Mismatched
beat gestures also biased what
they heard, with 40 per cent of
participants hearing the wrong
sound (Proceedings of the Royal
Society B, doi.org/fsjx).
This could be a learned
association, but there could be
an evolutionary reason behind
it, says Wim Pouw at Radboud
University in Nijmegen, who
wasn’t involved in the research.
Although only tested in Dutch,
Bosker says similar effects may be
seen in other similar languages
such as English, and may even
be present in all languages. “This
effect could be generalised to
much more than just Dutch, but
this is highly speculative,” he says.
Bosker says that his research is
even more important during the
current coronavirus pandemic
because of mask wearing. ISJAC
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