42 | New Scientist | 14 November 2020
O
N 9 MARCH, Mark Rutte, the Dutch
prime minister, called a press
conference to discuss his country’s
response to the covid-19 pandemic. “From
now on, we stop shaking hands,” he declared –
before promptly reaching out his hand to
greet an expert on infectious diseases.
Many of us can empathise. Social
distancing sounds innocuous, but this year
we have discovered how hard it can be in
practice. Touchy-feely greetings, such as
handshakes, hugs, kisses and nose rubbing,
are deeply embedded in many cultures.
These gestures aren’t merely learned,
however. Look to the animal kingdom and
you will see that many species – especially
highly social ones – perform physical rituals
when they approach each other. If our urges
to touch one another in greeting seem
instinctual, it is because they are.
Greetings adopted by animals can be
very different to our own – they include
eye poking and other gestures that might
make you squirm – but understanding
these behaviours can give us an insight into
human salutations. Examining the evolution
of greetings throws light on the subtle ways
they lubricate social interactions and also
helps to explain why they are so diverse.
As we are a super-social species, it isn’t
surprising that many of us are struggling
to adjust to the new normal. But the good
news is that we are proven masters at
adapting our greetings to fit new situations.Animal encounters
Mammals tend to use scents to suss each
other out, which explains why their greetings
are so intimate. A new encounter often
entails sniffing another individual’s face,
flanks and genitals for volatile chemicals that
reflect its hormonal state. This offers cues
about strength and fertility, allowing animals
to size up potential opponents and mates.
Like our own greetings, the duration and
intimacy of such exchanges reflect the nature
of the relationship. Subordinate rats, for
example, submit to prolonged sniffing from
more dominant individuals but risk a fightif they become over-friendly themselves.
They seem to be offering some kind of
“appeasement signal” that de-escalates
tension – and it’s not just about the chemical
signals in their body odour. Daniel Wesson
at Case Western Reserve University in Ohio
has found that rats that have lost their sense
of smell still sniff one another, suggesting
that the behaviour itself is also important
in establishing the social hierarchy.
Cats and dogs behave similarly, with a
characteristic rub of the head to exchange
smells on greeting. There is evidence that
such gestures can even spread goodwill
across the species barrier. A study of cats
and dogs living in the same household
found that 75 per cent regularly engage in
nose-to-nose sniffing, a gesture that appears
to help them live side by side. This can be
accompanied by other physical signals:
a cat’s raised tail signals friendly intent,
while a dog may crouch and look upward
to show that it has no intention of fighting.
For more elaborate greetings, however,
we need to look to our fellow primates, many
of which appear to use ritualised signals
as a way to navigate social relationships.
In certain species of baboon, for example,
greetings range from lip-smacking and
head-bobbing to touching buttocks or
genitals. Some baboons even engage in a
kind of conga dance. “They have this very
peculiar greeting, during which one male
approaches the other one, and he takes
the hind quarter of the other and then they
start walking,” says Federica Dal Pesco at
the German Primate Center in Gottingen.
Many of these behaviours – particularly
those involving genitals – include an element
of risk and vulnerability. “It’s really important
that they don’t get injured there because of
their future reproductive success,” says Dal
Pesco. From an evolutionary point of view,
such behaviours should be a serious taboo,
unless there is a significant benefit to
outweigh the danger. But what could it be?
The answer, Dal Pesco believes, lies in the
structures of baboon societies. She points out
that riskier and more intimate behaviours are
AN more common among highly cooperativeDREU
DALMAU
/EPA-EFE/SHUTTE
RS
TOCK“ Greetings help
individuals test
their trust in
each other and
build alliances”
Will our greetings
change for good as
a result of covid-19?