Human communication
Gesture politics
People talk a lot, but their hand signals may convey more useful information
Oct 28th 2010
Silence is golden
IT IS received wisdom that humanity owes a lot of its evolutionary success to its remarkable
ability to communicate. So much so, in fact, that few have bothered to test this hypothesis in
any systematic way. Now, a group of researchers led by Andrew King, of the Royal Veterinary
College in Britain, has tried to plug this gaping hole. Their first results have just been
published in Biology Letters.
Hunter-gatherers’ practice of scouring their surroundings for edible plants is responsible for
half of the name anthropologists have bestowed on them. And for good reason. With hunting
likely to have been an intermittent diversion, effective foraging would have been crucial to
tiding early humans over to the next woolly mammoth. So Dr King and his colleagues
conducted a study to see how, if at all, communication enhances foraging prowess.
They recruited 121 visitors to, rather appropriately, the London Zoo, and split them into 43
groups. Each group contained between two and seven people. Some were single-sex and
some mixed. Some were composed of family and friends whereas others brought together
complete strangers. Half the groups were allowed to communicate freely. The rest were told
to exchange no verbal signals or gestures of any kind.
Each group was then asked to a room containing six foraging patches—boxes filled with 300
cards, some green and some white—arranged at a distance from a central home base. The
green cards were defined as good and the patches varied from 5% to 95% green. The
foragers could not see inside the boxes and were allowed to pick only one card at a time,
through a hand hole, using their dominant hand. There were no restrictions on which patches
to visit, but each time a card was plucked it had to be returned to the home base,
irrespective of colour. The goal was to collect as many good cards as possible in an
unspecified short period of time (all trials actually lasted ten minutes). As an incentive,
members of the best-performing group would receive an animal-adoption prize worth £30
($47).
Before the modern-day foragers were let loose, radio-frequency tags, like those used in swipe
cards, were wrapped around everyone’s dominant wrist. All the good forage cards were
similarly tagged. These, together with antennae on top of the boxes and in the home base,
allowed Dr King to track the group members’ precise movements. That, in turn, made it
possible to determine how long it took each group to reach a consensus, defined as
concentrating more than 90% of activity around a single patch.
Unsurprisingly, the groups that were allowed to communicate proved the more effective
foragers. They were much likelier than their non-communicating peers to converge on the
greenest patches. What did come as something of a surprise, however, was the nature of the
communication that mattered. The researchers monitored noise levels and hand gestures.
Noise levels served as a proxy for verbal communication; gestures, for the non-verbal sort.
Dr King found that the only thing which explained the probability of lighting on the best patch
was gesture use, which peaked just before consensus was reached. Noise levels remained
more or less constant the whole time, suggesting that verbal messages were not as
important.
Constant volume may hide the variable importance of what was said. So, Dr King plans to
repeat the experiment, controlling for the meaning of both utterances and gestures.
Moreover, hand gestures are a relatively local signal. It remains an open question whether
they are as crucial to success in groups larger than the half-dozen or so people typical of
foraging parties in hunter-gatherer societies. Spoken contributions allow information to be
disseminated rapidly to group members far away. That may trump the importance of nonverbal messages as groups grow larger. But if gestures convey some vital extra information,
people in larger groups may limit their communication to nearby co-foragers. This might lead
to the emergence of subgroups.
How all this pertains to the “hunter” in “hunter-gatherer” has yet to be investigated. Getting
a project on that past an ethics committee might involve an interesting act of communication
in its own right.
Science and Technology
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