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WE all
have something of the Greek god in us. Proteus to be precise, who outwitted
his enemies by constantly changing his shape. Humans may not go as far as
transmogrification but when it comes to confusing a rival, our talent for
erratic behaviour is second to none.
A rabbit
pursued by a fox will bob and weave in a chaotic zigzag, rather than make
a beeline for cover. Other animals use different forms of random behaviour
to evade predators or catch their prey. But humans are the only ones who
rely on unpredictability as a weapon in competition against each other,
whether it be in a game of football or in international diplomacy.
Such behaviour
has long been ignored, but researchers are now waking up to the fact that
not only can we behave in very random ways, but that such actions are far
from pointless. Unpredictable behaviour may have evolved as a way of keeping
our rivals in the dark. This could explain some of our strangest behaviour,
such as sudden mood swings, and it also adds a whole new dimension to understanding
the evolution of human intelligence. Our highly developed sense of the
erratic may be the spark that allows an ape adapted for savannah living
to paint the Sistine Chapel, design the space shuttle and invent advertising
slogans.
British
biologist Michael Chance coined the phrase "protean behaviour" in 1959,
while at the University of Birmingham. But the evolutionary explanation
for this phenomenon is less than a decade old. It began with the observation
by two British ethologists, Peter Driver and David Humphries, that many
animals develop cognitive capacities so that they can predict the actions
of their competitors or prey. Natural selection then favours mechanisms that
make these actions harder to predict, so their enemies evolve better predictive
powers, and an evolutionary arms race develops.
False
signals
Two obvious
ways of making your actions harder to predict are hiding your real intentions
and giving out false signals. Both of these, however, are still vulnerable
to the evolution of even better perceptual mechanisms on the part of the
enemy, and so are not evolutionarily stable strategies - in other words,
the arms race continues. In many conflicts the only way to stop this escalation
is to adopt what game theorists call a "mixed strategy", which bases decisions
on probability. No amount of predictive talent will then prevail.
Submarine
commanders in the Second World War hit on this idea and resorted to throwing
dice to choose random patrol routes and so evade destroyers. In nature,
interactions between enemies often work in a similar way. Sand eels, for
example, usually react to predators by bunching together and swimming in
a fast-moving school. But when threatened in a narrow pool, they behave
very differently; the school breaks up and each eel darts about in
random directions in an attempt to confuse the predator.
Driver
and Humphries realised that protean behaviour should be common because of
the competitive edge it gives species. Once they began looking, they found
examples everywhere. There was the mobbing behaviour of gulls, which dive-bomb
intruders from all directions to try to protect nesting colonies. And the
herds of impala that burst into a whirlpool of activity, racing and plunging
in every direction when disturbed.
Proteanism
could also make sense of some of the more bizarre interactions between
predators and prey. Many birds feign injury to lure the enemy away from
a nest full of fledglings, using random changes in speed and direction
to balance their aims of drawing attention away from their young and ensuring
their own survival. Another puzzle - why moths, lizards and mice have mock
convulsions when attacked - makes sense as a way of throwing a predator
off its stride.
Competitive
situations also bring out the Proteus in humans. But when biologists looked
at people, they noticed an important difference between us and other animals
- our competitors tend to be other humans. Geoffrey Miller, a psychologist
at University College London, recently highlighted this and suggested that
this refinement in behaviour in our ancestors is key to our unique cognitive
style. Our talent for thinking randomly may even be a source of the creative
flare that sets humans apart from other animals.
Miller's
ideas build on the theory of Machiavellian intelligence, which proposes
that the main driving force in the evolution of human intelligence was the
need to predict and manipulate the behaviour of other humans. The special
cognitive capacities that evolved to deal with the social environment have
been dubbed social intelligence. This includes calculated deception and
its detection, but not protean behaviour. Miller argues that, in common
with many other animals, our monkey-like ancestors had a basic ability to
act randomly that they evolved to outwit predators. But during the transition
from monkeys to apes to early hominids, this protean capacity was boosted
by positive feedback from social intelligence, as outwitting our fellow humans
became more important than outwitting other animals. As a result, he claims,
proteanism plays a pivotal role in social intelligence.
Random
rage
Miller
gives the following example to illustrate why protean behaviour would have
evolved. Suppose our ancestors could have adopted one of two strategies for
setting their anger threshold - the point at which they lose their temper.
In the "Old Faithful" strategy, the anger threshold is fixed. Those who adopt
this strategy get angry only if an insult exceeds some predetermined level
of annoyance. In the "Mad Dog" strategy, on the other hand, the anger threshold
varies randomly. Sometimes a big insult does not generate a response, but
sometimes a small insult does. Which strategy would have been more effective?
If you
are using Old Faithful, others quickly learn what they can get away with,
so they constantly push you to the limit. But against the Mad Dog strategy
any insult, however slight, might trigger retaliation. Furthermore, the
person using this strategy does not have to waste time and effort punishing
every small insult, because the uncertainty does most of the work. Flare
up for no apparent reason every now and then, and people will tend to tiptoe
around you. So Mad Dog is a much more effective way of outwitting your competitors.
"This might
shed some light on the otherwise inexplicable nature of moods," says Miller.
When people explode over a minor insult that they would normally have laughed
off, we assume that some particular event has triggered their bad mood.
Miller, however, suggests that some moods may not be caused by any specific
stimulus. "They may simply be random alterations of our emotional state,"
he says. "The tendency to have such random mood changes could be a form of
protean behaviour that evolved to make us less predictable and so less easy
to exploit."
But are
we really natural born randomisers? Until a few years ago, most psychologists
thought that humans were incapable of truly random behaviour. Dozens of
studies seemed to confirm the view that producing a random series of responses
is difficult, if not impossible for humans. But most of these experiments
involved placing people in very artificial, non-competitive situations.
Often, the researcher simply asked an isolated subject to write down a series
of numbers with an instruction such as "be as random as possible". If proteanism
in humans evolved as a way of outwitting other humans, as Miller argues,
then people's failure to generate random numbers in these situations is not
surprising. "Psychologists failed to tap into our natural randomising abilities
because they didn't expose subjects to the social games where those abilities
evolved," says Miller.
So in 1992,
two Israeli psychologists set out to test people in face-to-face competition.
David Budescu of the University of Haifa and Amnon Rapaport of the Hebrew
University of Jerusalem got people to play a game called matching pennies.
The rules are simple. Two players start with an equal number of coins.
Each turn, both players simultaneously place a coin on the table between
them. If the coins match (heads-heads or tails-tails), player A keeps both
coins; if not, player B keeps them.
Though
the players have opposite objectives, they both benefit from being able to
predict what the other person will do next, and from making their own moves
hard to predict. Mathematically, the best strategy is to pick heads and tails
with equal probability, in a truly random series. Then over a long period
of play, your contestant cannot gain the advantage. And this is exactly
what Budescu and Rapaport found. The sequences of heads and tails generated
by the two players came very close to true mathematical randomness, even
though the players were given no instructions to that effect.
Another
indication that randomness is an innate ability comes from the work of
Allen Neuringer of Reed College in Portland, Oregon. He has shown that
humans can learn to generate random sequences when given feedback. In one
experiment, Neuringer asked students to generate a random series of a hundred
pairs of 1s and 2s at a computer terminal. He then told the students how
well they had done, measuring their performance by whether, for example,
the series included approximately equal amounts of 1-1, 1-2, 2-1 and 2-2.
In the first trial, the series was always nonrandom, but after several
trials, the students' performances improved to the point that their series
could not be distinguished from those generated by a computer.
A rat can
learn to press a lever if you give it food as a reward, so is it surprising
that students learn to generate random numbers? Yes, says Miller. The rat's
behaviour is an example of conditioning - give it the right feedback and
it will learn a new trick. But conditioning works by gradually eliminating
random variation. "It could never reinforce randomness itself," he says.
This leads him to conclude that there must be some innate randomising mechanism
built into the mind. "A roulette wheel in the head" is the metaphor used
by John Maynard Smith of the University of Sussex. "All sorts of processes
can generate effectively random series, so there is nothing bizarre about
the idea that the brain might be able to do so," he says.
Many animals
seem to have this mental roulette wheel but, argues Miller, by refining
its abilities humans have developed a mechanism that is capable of more
than simply outwitting enemies. Our super-protean capacity is the basis for
our inventiveness and artistic creativity, he says. "Proteanism provides
a key element of creativity that other mental mechanisms lack - the capacity
for rapid, unpredictable generation of highly variable alternatives," says
Miller. Studies of human creativity often emphasis this element. Without
it, for example, there would be no brainstorming. And in many forms of art,
from music to comedy, coming up with a new twist on an old theme or confounding
an audience's expectations is the key to success.
The prevailing
view is that human creativity came about as a lucky accident, through the
increasing overlap of cognitive capacities designed for other functions.
Ecological intelligence evolved to meet the complex demands of foraging
for food in the savannah, technical intelligence developed with our tool-making
skills, and social intelligence with group living. In a recent book, Steven
Mithen, an archaeologist at the University of Reading, argued that in the
early hominid mind these intellectual specialities were walled off from
each other like the chapels of an early cathedral. He claims that the modern
mind evolved only with the collapse of these mental divisions and the development
of more general cognitive capacities.
Creative
spur
The problem
with this view, says Miller, is that it is at odds with one of the main
features of natural selection—that it tends to lead to increased
specialisation rather than increased generalisation. Miller's theory, however,
requires no appeal to increasingly general mechanisms. On the contrary, an
innate randomising mechanism could well be a very specialised way of generating
novel ideas. Miller speculates that it might work by amplifying the quantum
mechanical noise in synaptic activity. Alternatively, it could work in the
same way that computers generate random numbers: producing pseudo-randomness
by feeding the numbers it generates back into a program that is too complex
to be worked out by an outsider.
According
to the Machiavellian intelligence hypothesis, creativity is a spin-off
from social intelligence alone. The idea is that our ancestors first evolved
to cope with savannah life, then learnt to exploit their environment using
tools, and finally perfected the art of social living. It was only then
that creativity really took off. But until now, nobody has come up with
a plausible explanation of how this might have happened. Miller's theory
could have the answer by showing how proteanism evolved in the social setting,
and then making the link between randomness and creativity.
Evolutionary
theorists have tended to see evolutionary adaptation as a process that
increases order and complexity. Natural selection was thought to build
improbable regularities from random disorder. Protean behaviour defies this
simple view - it is at once random and adaptive, chaotic and yet the result
of selection. No wonder it took biologists so long to see it.
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