Chapter 2

PSY 236Lifespan Development

William J. DavisGraduate Assistant

Department of Psychology

Central Connecticut State University

Exploring Your Inner FishAn Evolutionary Perspective

on Human Development – Part I

2

What Is Evolution?

On The Origin of Species (1859)Decent with Modification

Slow, Gradual ChangeContinuousEvolution v. Revolution

Progressive? Not Necessarily

Ecological NichesCompetition for ResourcesAdaptation

Survival of the FittestReproductive SuccessCost / Benefit

Charles Darwin1809 - 1882

3

Tiktaalik roseae

4

Sexual Selection: “The Peacock's Tale”

Video on Sexual Selection

5

Kin Selection & Inclusive Fitness

Kin SelectionIncrease the survival & reproductive success of close relatives.May decrease the individuals chance of survival.Altruism

Inclusive FitnessThe likelihood that shared genes will get passed to the next generation (via close relative)

(r b) – c > 0

6

Environment of Evolutionary Adaptiveness (EEA)

The environment to which a species is adapted“the only criterion by which to consider the natural adaptedness of any particular part of present-day man's behavioral equipment is the degree to which and the way it might contribute to population survival in man's primeval environment.” -- John Bowlby, 1982

Human EEA:hunter-gatherer; nomadiclow population density; small, kin-based groupsstone-age technologyhigh infant mortality & low life expectancyhigh vulnerability to the natural environmentfew lifestyle options than in later societies

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Evolution of Human Behavior: Two Examples

The Human Stress ResponseAdapted for the human EEAFight-or-FlightShuts down systems not immediately neededEnhances systems required to escape immediate threatDesigned for ACUTE activationCauses problems when activated CHRONICALLY

Risk-Taking BehaviorSex-differences: Women less likely to engage in risky behaviorsThe exception: In defense of their childrenFits evolutionary expectations

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Evolution of Infancy

Extended Infancy and Childhood in Primates

ProsimiansLifespan ~18 yearsChildhood ~2 years

MonkeysLifespan 25-30 yearsChildhood 4-7 years

Non-Human ApesLifespan 45-50 yearsChildhood 10-12 years

HumansLifespan 70-80 yearsChildhood 16-18 years

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Behavioral And Cognitive Growth

Immaturity as an Adaptive StrategyLarge Brains take time and resources to developLearning to navigate complex social environmentsIncreased plasticity of behaviorBetter ability to adapt to environmental challenges

Development Mediated by ParentsAttachment & Social DevelopmentSelective exposure to objects and eventsMimicry

Behavioral & Cognitive FlexibilitySlowly acquire & deploy behavior patternsFlexible representations of the worldBehavioral innovation in response to a changing environment

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Evolution & Longevity

Reproductive Benefits of Longevity

More offspringSuccessfully raising offspring to sexual maturityThe Grandparent Theory

Age related disorders compensated for by culture-based resources.

11

Some Cautions

BidirectionalityBiological Conditions ↔ Environmental ConditionsHumans are unique in that we can adapt our environment to our needs

Social DarwinismPerversion of valid scienceThe brutality of Natural Selection is NOT justification for brutality by humans toward weaker / less successful members of societyRacism - “race” is an artificial, socially constructed concept; Darwinism does not justify racial classification or racial animosity.