Bertvan
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Edward H. Hagen
Department of Anthropology
University of California at Santa Barbara
Intraspecific Exploitative Mimicry in Humans
Portions of this paper were presented at the Human Behavior and
Evolution Society Annual Meeting, Santa Barbara, CA, June 1995
http://www.sscf.ucsb.edu/~hagen/dd.html
Non-bizarre psychotic delusions are hypothesized to be psychological
adaptations which evolved to mitigate the dangerous consequences of
social exclusion and ostracism. When we lived in small, kin-based
groups, delusions would have functioned to combat social exclusion by
closely mimicking conditions, such as external threats or illness, where
fellow group members were likely to cooperate and provide assistance. If
delusions are adaptations to social exclusion, then they should onset
when an individual faces a serious social threat, they should function
(in ancestral type environments) to prevent exclusion-at least in the
short term-and they should cease when the social threat ceases, an
hypothesis which is examined in the context of numerous published
studies of Delusional Disorder (DD).
Studies of the role of life events in DD, studies of prison psychoses,
and studies of the relationship between both sensory impairment and
immigrant status with DD all indicate that social deficits play a
significant etiological role. Cross-cultural data collected in small,
kin-based societies show that individuals with delusions often receive
social benefits. Finally, studies show that positive social variables
are the most important predictors of good outcome for DD. A strong case
can therefore be made that delusions are an adaptation to social
exclusion. Proof of the hypothesis will require large, controlled
studies showing that social threats cause delusions, that individuals
with delusions living in small, kin-based groups frequently receive
social benefits-at least in the short term-and that the delusions
subside when the social threat subsides.