+

The Human Ancestral Environment and Persecutory Delusions

Spencer Head, Gabby Littlejohn, Amanda Lee, Anyssa Llerena

+Video: Where and how did humans evolve?

http://youtu.be/K4S2qJboi4I?t=1m50s

+Walston, F., Anthony, D.S., & Charlton B.D. (1998). Sex Differences in the Content of Persecutory Delusions: A Reflection of Hostile Threats in the Ancestral Environment?. Evolution and Human Behavior, 9, 257-260.

+Introduction

Humans are social animals

In males, ancestral alliances were mainly between/among blood relatives (Foley, 1995).

For females, ancestral alliances were between unrelated females (Essock, Vitale, & Mcguire, 1985). Therefore, women are more concerned with derogatory

gossip, rumors (Campbell, 1995). Fear exclusion from immediate circle

So, how does this apply to perceived threats (persecutory delusions)?

+Persecutory Delusions defined

DSM-IV-TR The person believes he/she is being "tormented,

followed, tricked, spied on, or ridiculed.” Most common form of delusion in schizophrenia Also very common in delusional disorder

+Hypotheses Men with persecutory

delusions will tend to identify male strangers as their persecutors

Females with persecutory delusions will tend to identify familiar females as their persecutors

In addition… Men would especially

identify strangers who are in groups (i.e., gangs)

Men’s persecutory delusions would be violent in nature, and women’s would be nonviolent

+Method

Used existing clinical notes of Anthony S. David, one of the study’s authors

Out of 500 cases, 24 of them had persecutory delusions where the persecutor(s) was/were specifically defined n = 24 n = 13 male, n = 11 female

+Results

+Results

Stranger Familiar0

2

4

6

8

10

1211

23

8

MalesFemales

Identity of Persecutor

Nu

mb

er

of

cases

+Discussion

Results support hypotheses regarding familiars vs. strangers 73% of women identified familiar people as persecutors 85% of men identified strangers as persecutors

However, sample is too small (n = 24)

Replicated by Julia Zolotova, Martin Brüne (2006). 63 inpatients (31 males, 32 females) of the Department of

Psychiatry, University of St. Petersburg, Russia 57 inpatients (25 males, 32 females) of the Department of

Psychiatry in Bochum, Germany Found similar results

+Critical points: Agreement

Very effective method: Walston, David, and Charlton used psychological disorders as a window to see the ancestral environment

Yielded results supportive of the hypotheses despite small sample

Implications of results can give a better understanding of social environment

+Critical Points: Disagreements

Small sample size

Sample isn’t necessarily generalizable to the overall population

Method is flawed: Retrospective Doesn’t address all hypotheses Doesn’t clearly operationalize definitions and formalize

measures