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Chapter 3

Chapter 3 Notes; Just like a textbook

Course Code
Ingrid L.Stefanovic

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Chapter 3
The Development of Evolutionary Theory
Charles Darwin – biological evolutionchanges that take place in the genetic and
physical characteristics of a population or group of organisms over time
Many behavioural differences among organisms, both within and across species,
correspond to genetic and other biological differences
Understanding these differences and their evolution allows psychologists to
understand behaviour in terms of its possible origins and adaptive significance
Adaptive significancethe effectiveness of behaviour in aiding organisms to adapt to
changing environmental conditions
What events and conditions in a persons lifetime might contribute to a tendency to
seek or to avoid novelty
What function does novelty seeking serve in helping people adapt to the changing
circumstances of life
What events and conditions in the evolution of our species favoured or punished
novelty seekers; what functions has novelty seeking served in the history of
Ultimate causesevolutionary conditions that have slowly shaped the behaviour of a
species over generations
- we behave as we do behave we are members of the human species
Proximate causesimmediate environmental events and conditions that affect
- because we have learned to act in special ways
Both biology and environment contribute to our personal development
No theory of behaviour can be complete without considering the role of
Culturethe sum of socially transmitted knowledge, customs, and behaviour patterns
common to a particular group of people
The Voyage of the Beagle
Beagles mission
-was to explore and survey the coast of South America and to make hydrographic

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measurements worldwide
-collect specimens
-Darwin - in theology - the doctrine of essentialism – Plato - all living things
belong to a fixed class of “kind, defined by an essence that characterizes it alone
The Origin of Species (Darwins book)(1838)
1836 ended voyage – back to England – discover many ways that animals and plants
adapt to their environments
Artificial selectiona procedure in which particular animals are deliberately mated
to produce offspring that possess especially desirable characteristics
Natural selectionthe consequence of the fact that, because there are physical and
behavioural differences among organisms, they reproduce differentially. Within a
given population, some animals – the survivors – will produce more offspring than
will other animals
-possesses a characteristic that helps it to survive or adapt to change in its
environment = live longer and produce more offspring
Natural Selection
Mayr (2000) – evolution can be traced to four insights:
1) species are not fixed, but rather change over time
2) evolution is a branching process, implying that all species descend from a single
common ancestor
3) evolution is continuous, with gradual changes
4) evolution is based on natural selection
key success of Darwin – natural selection with 2 premises
1) individuals within a population show variability in heritable behavioural and
physical characteristic
2) the capacity of the environment to sustain a population of any species is limited,
producing competition
reproductive successthe number of viable offspring an individual produces relative
to the number of viable offspring produced by other members of the same species
the evolutionarybottom line is not physical strength but reproductive success

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Two aspects of natural selection: variation and competition
Variationthe differences found across individuals of any given species in terms of
their genetic, biological (size, strength, physiology), and psychological (intelligence,
sociability, behaviour) characteristics
Genotypean organisms genetic makeup
- it determines how much the environment can influence an organisms development
and behaviour
Phenotypethe outward expression of an organisms genotype; an organisms
physical characteristics and behaviour
- every individuals phenotype is produced by the interaction of its genotype with the
Grants’ study
1) although evolution occurs over the long run, natural selection can produce
important changes in the short run – in the space of only a few years
2) phenotypic variation can produce important selective advantages that affect
Competitiona striving or vying with others who share the same ecological niche
for food, mates, and territory
natural selection works because the members of my species have different
allow only the best-adapted phenotypes to survive, thereby producing
evolutionary change
Heredity and Genetics (Darwins work)
Geneticsthe study of the genetic makeup of organisms and how it influences their
physical and behavioural characteristics
-the study of the structure and functions of genes, how they are transmitted from
one generation to another, and how they operate in populations
Heredity – the sum of the traits and tendencies inherited from a persons parents and
other biological ancestors
Individual differences occurred to species = natural selection
how adaptations were passed from parent to offspring or why
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