21 September 2019 | New Scientist | 7WE SEEM to have a natural
ability to communicate with
chimps. When tested, people
can usually understand
10 common hand gestures
used by chimpanzees. Human
infants use some of these same
gestures before they can talk,
although we don’t know if their
meanings are the same.
The gestures may be the
remnants of a basic sign
language used by our last
common ancestors with other
apes, says Kirsty Graham, who
did the work with colleagues
while at the University of St
Andrews, UK. “This gestural
communication is probably
biologically inherited among
the great apes – including
humans,” she says.
One idea about language
evolution is that we developed
the ability to speak by building
on a kind of sign language. To
investigate, Graham and her
colleagues have been recording
the gestures of gorillas, chimps
and bonobos. So far, they have
found 70 or so, with about
16 different meanings, as several
gestures can convey the same
message. Most are shared by
these three great apes.
The team set up a website
called the Great Ape Dictionary
where the public could watch
video clips of 10 common signs
made by chimps and bonobos,
and choose what each one
meant from four options.
By chance, they should get a
quarter of the answers right. But
they picked correctly 52 per cent
of the time, rising to 57 per cent
if given a brief description of the
situation in which the gesture
was used. Some signals – such as
a chimp stroking near its mouth,
which means it is asking for
food – were correctly matched
over 80 per cent of the time.Graham presented the
findings at the European
Federation of Primatology
meeting in Oxford, UK.
In a previous study, Adrian
Soldati at St Andrews looked at
whether preverbal children used
such signals. “Adults don’t need
to use gestures so much becausespoken language is so powerful,”
he says. He and his team filmed
13 German and Ugandan infants
between 1 and 2 years old
interacting with caregivers.
They defined gestures as
discrete movements during
periods of communication that
achieve nothing physically – so
it didn’t count if a child pulled
their parent towards an object,
for instance, but it did if they
gave a small, ineffectual tug.
Sometimes, the children
seemed to succeed at achieving
their goal, but not always.
The group recorded 52 kinds
of gestures, about 90 per centof which are also seen in
chimps. Although they didn’t
have enough material to
systematically study if the
children’s gestures meant
the same as those of the apes,
Soldati noticed a few such cases.
For example, if a child – or
chimp – reaches out with palm
uppermost, they are asking
for something. “They have this
similar toolkit of gesture types
that, at least in some of the
cases, they used for similar
goals,” says Soldati. “We kind of
inherited this repertoire.”
But there could be other
explanations for the way adults
can understand ape gestures,
says Thibaud Gruber at
the University of Geneva,
Switzerland. “Humans can
also recognise vocalisations,
for example, a strident high-
pitched call signals danger. You
don’t have to invoke [ancestry],
acoustics explains it. Some
of these gestures are pretty
obvious and self-explanatory.” ❚ARCO IMAGES GMBH/ALAMY STOCK PHOTOSome common hand
gestures may be
shared by all great apes52%
of the time people can identify
an ape hand signal’s meaningExtinctionColin BarrasICELAND was once home to many
walruses – and now we have the
clearest evidence yet that Norse
settlers hunted them to extinction.
We already knew these animals
once lived on Iceland, but opinion is
divided on whether they vanished
before or after humans arrived.
Xénia Keighley at the University
of Copenhagen in Denmark and
her colleagues carbon-dated the
remains of 34 walruses found in
western Iceland.
They found that three died after
AD 874, when permanent settlers
are thought to have arrived. One
died only in 1330 (Molecular
Biology and Evolution, doi.org/
dbjv). In other words, Icelandic
walruses survived for only a few
centuries after humans arrived.
In itself, this isn’t proof that
humans killed off the walruses, but
the researchers suspect that is the
case because there are accounts
of Vikings hunting the animals,
and ivory was valuable to them.
However, the team also considered
whether the walruses might have
fled from people, as happened on
other islands. “When hunters went
to Svalbard, the females and calves
moved away,” says Keighley.
But the study doesn’t support
that idea. The Icelandic animalshave a DNA signature that isn’t
found in any other population,
suggesting they didn’t interact.
This finding is intriguing, but
it is based on mitochondrial DNA,
which gives limited information,
says Bastiaan Star at the University
of Oslo, Norway. ❚Vikings probably
wiped out Iceland’s
walrusesCommunicationClare WilsonWe may share a basic
language with chimps
Walrus ivory
was a valuable
commodity to
early settlers
on IcelandJAMI TARRIS/GETTY IMAGES