The Scientific Movements Leading to

Evolutionary Psychology

Evolutionary Psychology

Landmarks in the History of

Evolutionary ThinkingEvolution before Darwin

Lamarck – species progress

toward higher forms/inheritance

of acquired characteristics

Cuvier – catastrophism, species

removed by events like

meteorites, then new species

emergeAlso, evidence from homologies,

strata of fossil record,

ontological similarities

What was the mechanism for

biological structures? How did

changes come about?

Landmarks in the History of

Evolutionary ThinkingDarwin’s theory of natural selection

Variation, selection, inheritance

Influence on Darwin

Malthus – organisms exist in numbers far greater

than can survive and reproduce (an essay on the

principle of population)

Differential reproductive success

Landmarks in the History of

Evolutionary ThinkingDarwin’s theory of sexual selection

Intrasexual competition

Sexual dimorphism, particularly size

Intersexual selection

Are natural and sexual selection different

processes?

Landmarks in the History of

Evolutionary ThinkingThe role of natural and sexual selection

in evolutionary theory

Genetic drift: random changes in the

genetic makeup of a population

Mutations, founder effect, and genetic

bottlenecks are all part of genetic drift

Founder effect: a small group breaks

off from larger population: their

characteristic are not representative of

populationGenetic bottleneck: event causes

demise of large portion of population;

those that survive have genes that

don’t represent population

Landmarks in the History of

Evolutionary ThinkingThe role of natural and sexual selection in

evolutionary theory (cont.)

Evolution is gradual (Lyell)

Darwin believed in blending of characteristics in

sexual reproduction (Mendel)

Objection of religious individuals (immutable life

forms)

Landmarks in the History of

Evolutionary ThinkingThe modern synthesis: Genes

and particulate inheritance

Darwin didn’t understand

mechanism of inheritance

Mendel’s work clears that up

(genes; particulate, not

blended)Mendel sent papers to

Darwin, but for reasons

unknown he did not absorb

their significanceThe modern synthesis is a

combination of Darwin’s

theory of natural selection

and Mendel’s work on

genetics

Landmarks in the History of

Evolutionary Thinking

The ethology movement

Natural selection of behavior

Darwin conceived on natural

selection’s effect on behavior

All behavior requires underlying

physical structures – bipedal

locomotionThrough artificial selection behavioral

characteristics can be changed

Ethology is concerned with species-

specific behaviors – those that are

genetically determined, like imprinting

Landmarks in the History of

Evolutionary ThinkingThe ethology movement (cont.)

Tinbergen’s four “why’s”?

1. Immediate influence on behavior

2. Developmental influences on behavior

3. Function of behavior

4. Evolutionary or phylogenetic origins of behavior

Landmarks in the History of

Evolutionary ThinkingThe inclusive fitness revolution

Hamilton – broadens the scope of natural

selection by including other relatives and the

importance of helping their genes get to the next

generationInclusive fitness is the sum of an individual’s own

reproductive success (classical fitness) plus the

effects the individual’s action have on the

reproductive success of his/her genetic relatives

Landmarks in the History of

Evolutionary Thinking

Clarifying adaptation and

natural selection

Trivers’ seminal theories

Reciprocal altruism

Parental investment theory

Sexual selection

Theory of parent-offspring

conflict

Landmarks in the History of

Evolutionary ThinkingThe sociobiology controversy

E.O. Wilson

Sociobiology: The New Synthesis (1975)

Cellular biology, integrative neurophysiology,

ethology, comparative psychology,

population biology, behavioral ecology

Ants to humans – theory could be applied to

all life forms

Synthesized into from:

Inclusive fitness

Parental investment theory

Parent-offspring conflict theory

Reciprocal altruism

Landmarks in the History of

Evolutionary Thinking

E.O. Wilson (cont.)

Gave a name to emerging field

Chapter on humans controversial

Sociobiology would ‘cannibalize’psychology

Claimed sociobiology would explain:

Culture

Religion

Ethics

Aesthetics

Theory lacked support from studies of

humans

Landmarks in the History of

Evolutionary Thinking

Common misunderstandings about evolutionary theory

Misunderstanding 1: human behavior is genetically

determinedMisunderstanding 2: if it’s evolutionary, we can’t change it

Misunderstanding 3: current mechanisms are optimally

designedMilestones in the origins of modern humans

Landmarks in the History of

Evolutionary ThinkingLandmarks in the field of psychology

Freud’s psychoanalytic theory

William James and the psychology of

instinctsThe rise of behaviorism

The astonishing discoveries of cultural

variabilityThe Garcia effect, prepared fears, and the

decline of radical behaviorism

Harlowe

Flavor aversion

Prepared fears – taste paired with different

stimuli yield different results

Peering into the black box: the cognitive

revolution