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The
social complexity hypothesis holds that the cognitive demands of
social living have been an important force driving the evolution
of intelligence. Although this idea has been applied mainly to primates,
we (Balda, Bednekoff & Kamil, 1997) have suggested that it could
also be applied to birds and that highly social pinyon jays (Gymnorhinus
cyanocephalus) might be a particularly appropriate avian species
with which to work. A great deal is known about their natural history
(Marzluff & Balda, 1992 ). In particular, pinyon jays live in
large, individualized groups which are very stable over time. We
have completed three experiments on socially-related cognition,
each of which supports the validity of the idea that living in stable,
socially complex groups provides a context for the evolution of
social intelligence.
Templeton, Kamil and Balda (1999) tested social learning in pinyon
jays and Clark’s nutcrackers (Nucifraga columbiana),
who are much less social than are pinyon jays. Birds were tested
on two different tasks under individual and social learning conditions.
Half of each species learned a motor task individually and a discrimination
task socially; the other half learned the discrimination task individually
and the motor task socially. While the pinyon jays learned the tasks
more rapidly under social than individual conditions, the nutcrackers
performed equally well under both learning conditions.
Bond, Kamil and Balda (2003) used operant techniques to compare
pinyon jays with a relatively nonsocial close relative, western
scrub jays (Aphelocoma californica) on two complex cognitive
tasks relevant to the ability to track and assess social relationships.
Pinyon jays learned to track multiple dyadic relationships more
rapidly and more accurately than scrub jays and appeared to display
a more robust and accurate mechanism of transitive inference. These
results provide a clear demonstration of the association between
social complexity and cognition in animals.
Paz-Y-Mino, Bond, Kamil and Balda (2004) tested an important implication
of these operant results. The basic rationale of the social complexity
hypothesis is that living in large, stable social groups may favor
the evolution of enhanced cognitive abilities, such as recognizing
group members, tracking their social status, and inferring relationships
among them. Because conflicts within a group can be time-consuming
and even injurious, members of large social groups could benefit
if they can make judgments about relationships based on indirect
evidence, using transitive inference, which would allow assessment
of relationships from observations of interactions among others.
Transitive inference, however. has never been demonstrated under
controlled conditions in animals. In this experiment, we found that
pinyon jays did, in fact, draw sophisticated inferences about their
own dominance status relative to that of strangers based on interactions
that they observed, the first direct demonstration that animals
use transitive inference in social settings.
References
Cited:
Paz-y-Miño
C, G., A.B. Bond, A.C. Kamil & R.P. Balda. (2004) Pinyon jays
use transitive inference to predict social dominance. Nature
430: 778-781. PDF
Bond, A.B., Kamil, A.C. & Balda, R.P. (2002). Social complexity
and transitive inference in corvids. Animal Behaviour, 65:
479–487. PDF
Templeton,
J.J., Kamil, A.C. & Balda, R.P. (1999). Sociality and social
learning in two species of corvids. Journal of Comparative Psychology
113: 450-455.
Balda,
R.P., Kamil, A.C. & Bednekoff, P.A. (1997). Predicting cognitive
capacities from natural histories: Examples from four corvid species.
Current Ornithology 13: 33-66.
Marzluff,
John M., & Russell P Balda (1992). The Pinyon Jay: Behavioral
Ecology of a Colonial and Cooperative Corvid. London: T&AD
Poyser.
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