Download Evolutionary Psychology

Evolutionary Psychology
Learning Objective:
Examine one evolutionary explanation of
behavior.
What is evolutionary psychology?
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Based on key principles of the biological
level of analysis
1. Predisposition for certain behaviors is
inherited
2. Genetically based behaviors of an individual
who has reproduced are passed on
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Key assumption
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Genetically based behaviors of unsuccessful
individuals are lost over time
Behaviors that exist today must have been
adaptive in the past
Often study animals and relate to human
behavior
Theory of Natural Selection
• Definition: members of a species who
have characteristics which are better
suited to the environment will be more
likely to breed
– Thus…pass on traits
• Adaptation
Curtis et al 2004
• Theory: Disgust has evolved as a food-rejection
response to prevent contamination and the spread of
illness
• Hypothesis: There are patterns in disgust response
• Method: Web-based Survey
• Procedure: 77,000 participants, 165
countries
– shown 20 images in pairs and ranked disgust response
• One was potentially harmful to the immune system and the was
non-infectious
• Results
– Disgust was stronger for images that threaten the immune
system
– Disgust was higher in young people (reproduction age)
– Women had higher levels of disgust
Disgust in pregnant women
• Pregnancy
– Nausea and loss of appetite during pregnancy is
necessary for survival
Fessler et al (2005)
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Hypothesis: elevated disgust sensitivity
is an evolutionary behavior
Method: Web-based survey
Procedure
– 691 women who were not paid
1. Survey about current level of nausea
2. Disgust sensitivity in 8 different areas
• Results
– Disgust was higher in the 1st trimester
– Higher in relation to food
• Implications
– Food-born diseases are more dangerous in the 1st
semester  evolutionary development of nausea
• Evaluation
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Supports Curtis et al. 2004
Groups size was sufficient
Self-reports may not be reliable
May be reliable if they were actually confronted with
real disgust-eliciting objects
• Is that ethical?
Evaluation of Evolution Theories
• It is difficult to tests
– Not much is known about the early life of
humans
• Underestimate cultural influences
– Over-emphasis on biology
Read and Take Notes
• Add to your class notes (non Cornell)
– Page 62-63
• Can homicide and homosexuality be
adaptive behavior?