Evolutionary Perspectives on Personality. Copyright © 2005 The McGraw-Hill Companies, Inc....

Evolutionary Evolutionary Perspectives on Perspectives on

PersonalityPersonality

Copyright © 2005 The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Origin TheoriesOrigin Theories

Three theories of the origins of Three theories of the origins of complex adaptive mechanismscomplex adaptive mechanisms


1. Creationism1. Creationism


2. Seeding theory2. Seeding theory


3. Evolution by natural selection3. Evolution by natural selection


Evolution and Natural Evolution and Natural SelectionSelection

All humans today come from an All humans today come from an unbroken line of ancestors who unbroken line of ancestors who accomplished two tasks: They accomplished two tasks: They survived to reproductive age, and survived to reproductive age, and they reproducedthey reproduced

We carry adaptive mechanisms that We carry adaptive mechanisms that led to our ancestors’ successled to our ancestors’ success


Natural SelectionNatural Selection

Changes or variants that better Changes or variants that better enabled an organism to survive and enabled an organism to survive and reproduce lead to more descendantsreproduce lead to more descendants

Descendants inherit variants that led Descendants inherit variants that led to their ancestors’ successto their ancestors’ success


Natural SelectionNatural Selection

Thus, successful variants are Thus, successful variants are selected and unsuccessful variants selected and unsuccessful variants are weeded outare weeded out

Over time, successful variants come Over time, successful variants come to characterize entire speciesto characterize entire species


Sexual SelectionSexual Selection

Darwin noticed that many mechanisms Darwin noticed that many mechanisms seemed to threaten survival, such as seemed to threaten survival, such as the peacock’s elaborate plumage and the peacock’s elaborate plumage and the stag’s large antlersthe stag’s large antlers

Darwin proposed evolution by sexual Darwin proposed evolution by sexual selection as solution—these traits selection as solution—these traits evolved because they contributed to evolved because they contributed to an individual’s mating successan individual’s mating success



Two forms of sexual selectionTwo forms of sexual selection Intrasexual competitionIntrasexual competition: Members of : Members of

the same sex compete with each other the same sex compete with each other for sexual access to members of the for sexual access to members of the other sexother sex

Intersexual competitionIntersexual competition: Members of : Members of one sex choose a mate based on their one sex choose a mate based on their preferences for particular qualities in preferences for particular qualities in that matethat mate


Genes and Inclusive Genes and Inclusive FitnessFitness

Differential gene reproduction—Differential gene reproduction—reproductive success relative to othersreproductive success relative to others

Calculate genetic gains and lossesCalculate genetic gains and losses Inclusive fitness theory (Hamilton, 1964)Inclusive fitness theory (Hamilton, 1964)

Inclusive fitness: personal reproductive Inclusive fitness: personal reproductive success (number of offspring you produce) success (number of offspring you produce) plus effects you have on the reproduction of plus effects you have on the reproduction of your genetic relatives, weighted by genetic your genetic relatives, weighted by genetic relatednessrelatedness


Products of the Products of the Evolutionary ProcessEvolutionary Process

AdaptationsAdaptations Byproducts of AdaptationsByproducts of Adaptations Noise or Random VariationNoise or Random Variation


AdaptationsAdaptations

Adaptations are the primary Adaptations are the primary products of selection, defined as products of selection, defined as “reliably developing structure in the “reliably developing structure in the organism which, because it meshes organism which, because it meshes with the recurrent structure of the with the recurrent structure of the world, causes the solution to an world, causes the solution to an adaptive problem”adaptive problem”


AdaptationsAdaptations

Adaptive problem: Anything that Adaptive problem: Anything that impedes survival or reproductionimpedes survival or reproduction

Hallmark of adaptations are special Hallmark of adaptations are special design, including efficiency, design, including efficiency, precision, and reliability.precision, and reliability. E.g., food preferences, fear of snakesE.g., food preferences, fear of snakes E.g. Jealousy, helping, defense E.g. Jealousy, helping, defense

mechanismsmechanisms


Byproducts of Byproducts of AdaptationsAdaptations

Byproducts are incidental effects Byproducts are incidental effects of adaptations not properly of adaptations not properly considered to be adaptationsconsidered to be adaptations e.g., nosee.g., nose e.g., language?e.g., language?


Noise or Random Noise or Random VariationVariation

Neutral with respect to selectionNeutral with respect to selection e.g., shape of the human earlobee.g., shape of the human earlobe


Evolutionary PsychologyEvolutionary Psychology

Premises of Evolutionary Premises of Evolutionary PsychologyPsychology Domain-specificityDomain-specificity: Adaptations : Adaptations

are designed by evolutionary are designed by evolutionary process to solve specialized process to solve specialized adaptive problemsadaptive problems



Premises of Evolutionary Premises of Evolutionary PsychologyPsychology NumerousnessNumerousness: Expectation is that : Expectation is that

there are many psychological there are many psychological adaptations, because different adaptations, because different adaptations are required to solve adaptations are required to solve different adaptive problemsdifferent adaptive problems



Premises of Evolutionary Premises of Evolutionary PsychologyPsychology FunctionalityFunctionality: Psychological : Psychological

adaptations are designed to adaptations are designed to accomplish particular adaptive accomplish particular adaptive goalsgoals


Proximate and Ultimate Proximate and Ultimate CausationCausation

Proximate causation: Immediate causal Proximate causation: Immediate causal forces—development, input, mechanismforces—development, input, mechanism E.g., defense mechanisms used to avoid E.g., defense mechanisms used to avoid

anxietyanxiety Ultimate causation: Why? [example: Ultimate causation: Why? [example:

Why are men taller than women, on Why are men taller than women, on average?]average?] E.g., why do defense mechanisms exist?E.g., why do defense mechanisms exist?


Core Tenets of Evolutionary Core Tenets of Evolutionary PsychologyPsychology

Evolved psychological mechanisms Evolved psychological mechanisms are instantiated in the brain.are instantiated in the brain.


Human NatureHuman Nature

Human nature is a product of Human nature is a product of evolutionary processevolutionary process

Psychological mechanisms that are Psychological mechanisms that are successful in helping humans successful in helping humans survive and reproduce out-replicate survive and reproduce out-replicate those that are less successfulthose that are less successful



Over evolutionary time, successful Over evolutionary time, successful mechanisms spread through population mechanisms spread through population and come to characterize all humansand come to characterize all humans

Examples of evolutionary analysis at the Examples of evolutionary analysis at the level of human naturelevel of human nature The Need to BelongThe Need to Belong Helping and AltruismHelping and Altruism Defense MechanismsDefense Mechanisms Universal EmotionsUniversal Emotions



The Need To Belong

The most basic human motivators are status and acceptance

Social Anxiety – species typical adaptation to prevent social exclusion

Being part of a group has survival value



Helping and Altruism

Helping others is a direct function of the recipient’s ability to enhance the inclusive fitness of the helper

The tendency to help is a direct function of genetic relatedness



Helping and Altruism

Who do you save from a burning building? Son vs. nephew? Son vs. daughter? Spouse vs. child?



Defense Mechanisms

Ability to deceive self (DM) increases ability to deceive others

Deceiving others increases likelihood of survival and mating success E.g., threats, boss


Sex DifferencesSex Differences

Evolutionary psychologists expect Evolutionary psychologists expect that males and females will be the that males and females will be the same or similar in all domains where same or similar in all domains where sexes have faced the same or similar sexes have faced the same or similar adaptive problemsadaptive problems

Expect sex differences in those Expect sex differences in those domains where sexes recurrently domains where sexes recurrently faced different adaptive problemsfaced different adaptive problems



Examples of differences between men Examples of differences between men and women that are attributable to and women that are attributable to recurrently facing different adaptive recurrently facing different adaptive problemsproblems Sex Differences in AggressionSex Differences in Aggression Sex Differences in JealousySex Differences in Jealousy Sex Differences in Desire for Sexual Sex Differences in Desire for Sexual

VarietyVariety Sex Differences in Mate PreferencesSex Differences in Mate Preferences



Jealousy

Adaptive problem for men is paternity. Men over evolutionary history have risked investing

in children who were not their own Adaptive problem for women is child-rearing

resources. Women over evolutionary history have risked raising

children without adequate resources



Jealousy

Males and females have evolved different jealousy cues

Men should be more jealous in response to cues to a sexual infidelity

Women become more distressed over a partner’s emotional infidelity



Basic Method

Think of a serious, committed romantic relationship that you have had in the past, that you currently have, or that you would like to have. Imagine that you discover that the person with whom you’ve been seriously involved has become more interested in someone else. Of the following, which would distress or upset you more?

1. Imagining your partner forming a deep emotional attachment to that person.

2. Imagining your partner enjoying passionate sexual intercourse with that person.



Jealousy

Findings

Universal

Problems

Forced choice only

Double shot



Mate Preferences

Evolutionary psychology predicts:Men value women’s physical appearance

which provides cues to her fertilityWomen value men’s financial resources

which help in raising the family


Individual DifferencesIndividual Differences

Most challenging and difficult level of Most challenging and difficult level of analysis for evolutionary psychologistsanalysis for evolutionary psychologists

Big Five personality traits as clusters of Big Five personality traits as clusters of key features of “adaptive landscape” of key features of “adaptive landscape” of other peopleother people

Human have evolved “difference-Human have evolved “difference-detecting mechanisms” designed to detecting mechanisms” designed to notice and remember individual notice and remember individual differences that have most relevance for differences that have most relevance for solving social adaptive problemssolving social adaptive problems


Limitations of Evolutionary Limitations of Evolutionary PsychologyPsychology

Adaptations are forged over long expanse Adaptations are forged over long expanse of evolutionary time, and we cannot go of evolutionary time, and we cannot go back to determine with certainty what the back to determine with certainty what the precise selective forces on humans have precise selective forces on humans have beenbeen Forced to make inferencesForced to make inferences But current mechanisms provide windows But current mechanisms provide windows

for viewing the pastfor viewing the past Learning more about our evolved Learning more about our evolved

mechanisms is a tool for overcoming mechanisms is a tool for overcoming limitation of sparse knowledge of ancestral limitation of sparse knowledge of ancestral environmentsenvironments



Evolutionary scientists have just Evolutionary scientists have just scratched the surface of understanding scratched the surface of understanding the nature, details, and design features the nature, details, and design features of evolved psychological mechanismsof evolved psychological mechanisms

Modern conditions are undoubtedly Modern conditions are undoubtedly different from ancestral conditions in different from ancestral conditions in many ways, and so what was adaptive many ways, and so what was adaptive in the past might not be adaptive todayin the past might not be adaptive today



It is sometimes easy to come up with It is sometimes easy to come up with different and competing evolutionary different and competing evolutionary hypotheses for the same phenomena—true hypotheses for the same phenomena—true of all scienceof all science Onus is on the researcher to fashion Onus is on the researcher to fashion

specific, testable, and falsifiable hypothesesspecific, testable, and falsifiable hypotheses Thus, competing theories can be pitted Thus, competing theories can be pitted

against each other and data can be the final against each other and data can be the final arbiterarbiter


Summary and EvaluationSummary and Evaluation(continued)(continued)

Evolutionary psychology has several Evolutionary psychology has several limitations, but this perspective adds limitations, but this perspective adds a useful set of theoretical tools to a useful set of theoretical tools to the analysis of personality at levels the analysis of personality at levels of human nature, sex differences, of human nature, sex differences, and individual differencesand individual differences

Evolutionary Perspectives on Personality. Copyright © 2005 The McGraw-Hill Companies, Inc....

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