A theory developed to study chess and poker offers an insight into why some animals cheat
IMAGINE this: 2 prisoners are charged
with a crime which they allegedly committed together. If neither confesses -
that is, they agree to 'cooperate' - each
will serve a term, say 1 year. If one honours the pact between the 2 prisoners to cooperate, while the other 'defects',
blaming the first prisoner for the crime,
the defector goes free while the cooperator serves 10 years in"Prison. If both
defect, both serve 4 years in jail.
Each prisoner reasons that defection
will ensure a shorter prison term (being
turned free against serving I year and a
4-year prison term against a 10-year
one). So both defect, and consequently,
both are sentenccd,to a 4-year prison
term. Also known as the Prisoner's
Dilemma, this is,'in fact, a traditional
model of the game theory, which
says that the 'best' strategy adopted by a
person is guided by the actions of another.
Evolutionary biologists now say that
applying the game theory to study animal behaviour could provide an answer
to questions such as why organisms
choose cooperation as the most-favoured or the least-favoured strategy
in different situations - from spiders
fighting over web sites to cooperation
amon@ fish. Such studies, apart from
providing an opportunity to verify, game
theory predictions, could also help in
understanding a wide range of animal
and even human behaviour, they argue
(Science, Vol 267, No 5204).
For instance, Stephen and Melinda
Pruett-Jones of the University of
Chicago, say that bowerbirds resort to
cheating for mating advantage. The scientists say that male bowerbirds build
elaborate bowers - structures of twigs,
leaves and other objects - to attract
females, but some of them also indulge
in damaging the bowers of other male
birds in their absence. The
'marauders' increase their
chances of success with the
females at the expense of their non-marauding rivals, making cooperation a losing strategy.
But cooperation can
become a viable strategy if
the players interact again
and again in an 'iterated
Prisoner's Dilemma', so
that they know w@'ho are
cooperating and who are
not. If somebody does not cooperate, a
tit-for-tat strategy could be adopted
towards that player subsequently. But
could a tit-for-tat strategy work in a real world?
Manfred Milinski of the University
of Bern, Switzerland, suggests that one
place to look for an answer is among
small fish, which face an 'iterated
Prisoners Dilemma' naturally.
When a large fish ventures near a
shoal of small fish, one or more of the
school approaches the big one to see
how dangerous it is. This predator
inspection, says Milinski, is risky for the
scouts, but the information can benefit
them as well as the rest -
if the big fish is not a
predator or is not hungry,
the smaller ones need not scatter.
The group of scouts
approaching a prospective
predator is playing out
a Prisoner's Dilemma,
argues Milmski. "Each has
a strong urge to defect and
let others take all the
chances, but if all defect
they learn nothing about
the big fish. Full cooperation, on the
other hand, minimises risks because the
predator becomes confused if it cannot
focus on a single target," he adds.
Milinski claims to have tested this
idea in sticklebacks, and found that the
fish indeed use tit-for-tat strategy for
predator inspection. If a scout fails to
make a move forward when its turn
comes, the other would also hold back.
"This model makes some new and very
interesting predictions about evolution
of cooperation," says Lee Dugatkin of
University of Missouri, Colombia.
Robert Axelrod, a political scientist
at the University of Michigan, even
suggests that the evolutionary game
theory may help in predicting the
strategies politicians employ during elections.
We are a voice to you; you have been a support to us. Together we build journalism that is independent, credible and fearless. You can further help us by making a donation. This will mean a lot for our ability to bring you news, perspectives and analysis from the ground so that we can make change together.
Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.