evolutionary the logic of natural selection psychology
TRANSCRIPT
EvolutionaryPsychology
Lecture 1
Lisa DeBruine
01224 27-2243
Room S7 William Guild Building
course website - http://facelab.org/evpsych
The logic of Natural Selection
• Organisms produce more offspring than can possibly be supported by the environment
• There is variation in how well-suited individuals are to their environment and this affects their chances of survival and reproduction
• Some of this variation is heritable
What can evolutionary theory tell us about behaviour?
• Help generate and evaluate hypotheses
• Recognize different types of behaviours
• Currently adaptive behaviours
• Previously adaptive behaviours
• By-products of adaptive behaviours
Currently Adaptive Behaviours
Previously Adaptive Behaviours
The desire to overeat fats and sweets when they are available was probably adaptive when these foods were rare and the main consequence was to motivate people to eat fresh fruit.
Previously Adaptive Behaviours
The inclination to delay childbearing and have fewer children when the environment is highly competitive and survivorship is high was probably adaptive up to a point. Now, research indicates that some modern women have followed this trend to a maladaptive extreme (Low, 2002).
By-products of Adaptive Behaviours
Some behaviours can be explained as by-products or “spandrels” (Gould & Lewontin, 1979).
Many behaviours are obviously not a result of natural selection for that specific behaviour, such as the ability to read or to ride a bike.
Criticisms of Evolutionary Psychology
• Evolutionary hypotheses are always just-so stories.
• Evolutionary hypotheses are unfalsefiable.
• Evolutionary psychology is intrinsically racist, classist, sexist, homophobic, etc.
• Explaining human behaviour using evolutionary theory is too reductionist.
Areas in which Researchers Use an Evolutionary Approach to Behaviour
• Medicine
• Biology
• Anthropology
• Experimental Economics
• Psychology
• Neuroscience
2D:4D and Testosterone
• Prenatal T influences the brain and (maybe) 2nd to 4th digit ratio.
• Low 2D:4D indicates high prenatal T levels.
• Low 2D:4D in men is correlated with musical ability, athletic ability, heterosexuality, and many other traits (Manning, 2002).
Cross-cultural diversity in use of spices
(Billing & Sherman, 1998)
Cross-cultural diversity in use of spices
(Billing & Sherman, 1998)
Use of spices varies with climate; data from 32 countries.
Norway is the coldest and Thailand is the hottest.
Prisoner’s Dilemma
cooperate
cooperate
defect
defect
Player 1
Pla
yer
2 3 3
5 0
0 5
1 1
Who do you think the baby is most similar to?
(Daly & Wilson, 1982)
Mother Father OtherRespondent: Mother 14 57 29 Father 17 54 29 Mo’s relative 29 53 18 Fa’s relative 20 47 33
Who would you help?
(Burnstein et al., 1994)
Genetic Compatibility
Women who were not using oral contraceptives rated the odours of MHC-dissimilar men (sharing 0 or 1 allele) to be more pleasant than the odours of MHC-similar men (sharing 3 or 4 alleles).
Women who were using the pill showed the opposite pattern.
(Wedekind et al.,1995)
0
1
2
3
4
5
6
7
Non-Pill Users Pill Users
MHC-similar MHC-dissimilar
Pleasantness ratings of male odours by females
Female Preferences for Masculinity over the Menstrual Cycle
0%
5%
10%
15%
short term context long term context
Me
an
fe
min
iza
tio
n p
refe
red
low conception riskhigh conception risk
mating offspring
sexdifferences
matechoice
perception
resources
altruism
reciprocity
kinselectioncostly
signaling
kinrecognition
cheaterdetection
parent-offspring conflict