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Lecture

Chapter notes


Department
Psychology
Course Code
PSYA01H3
Professor
Steve Joordens

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Roshan Singh
10/18/07
Mr. Joordens
PSYA01H3
Chapter 3 Notes
Biological evolutionChanges that take place in the genetic and physical characteristics of a population
or group of organisms over time. It stands as the primary explanation of the origin of life.
Adaptive significanceThe effectiveness of behaviour in aiding organisms to adjust to changing
environmental conditions.
Novelty seeking is the tendency to engage in behaviours that lead to new experiences. Individuals with
high score on novelty seeking tests are referred to as impulsive, exploratory or excitable whereas
individuals with low score are seen as reflective, stoic and slow tempered. In order to answer which one is
better, we must consider 2 main things:
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 humankind?
A complete understanding of novelty seeking requires that we understand both the past and present
conditions that influence it.
Ultimate causesEvolutionary conditions that have slowly shaped the behaviour of a species over
generations.
Proximate causesImmediate environmental events and conditions that affect behaviour.
We behave as we do because we do because we are members of the human species (ultimate cause) and
because we have learned to act in special ways (proximate cause). Both biology and environment both
contribute to our personal development.
Evolutionary psychologyThe branch of psychology that studies the ways in which organisms
evolutionary history contributes to the development of behavioural patterns and cognitive strategies
related to reproduction and survival during its lifetime.
CultureThe sum of socially transmitted knowledge, customs, and behaviour patterns common to a
particular group of people. Psychologys contribution to this understanding will be an explanation of how
thinking and behaviour shape cultural adaptations to changing environmental conditions.
Captain Robert Fitz Roy was looking for an unpaid naturalist and travelling companion during a five year
voyage on the HMS Beagle. The beagles mission was to explore and survey the coast of South America
and to make hydrographic measurements worldwide. Darwin collected creatures and objects which were
later sent back to England as they were viewed by other naturalists all over from Europe.
Artificial selectionA procedure in which animals are deliberately mated to produce offspring that
possess particularly desirable characteristics.
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Roshan Singh
10/18/07
Mr. Joordens
PSYA01H3
Chapter 3 Notes
Natural selectionThe consequence of the fact that, because there are physical behavioural differences
among organisms, they reproduce differentially. Within a given population, some animalsthe survivors
will produce more offspring than will other animals.
With the help of natural selection, Darwin realized his theory in September 1838, but he did not publish it
until 20 years in order to find supportive evidence. So, his theory would be clear and accurate. He would
have taken even longer if it werent for Alfred Wallace who had also discovered the principle of natural
selection. Wallace wrote down his idea and sent it to Charles Darwin and it gave Darwin a dilemma as to
whether or not he should publish his idea. They mutually agreed on presenting to the Linnean society as
to how they came about their theory and later that year Darwin published his book known as the origin of
species.
Mayr suggests that Darwins contribution can be traced to 4 insights:
Species are not fixed, but rather change over time
Evolution is a branching process, implying that all species descend from a single common
ancestor
Evolution is continuous, with gradual changes
Evolution is based on natural selection
Natural selection is based on 2 premises:
Individuals within a population show variability in heritable behavioural and physical
characteristics.
Capacity of the environment to sustain a population of any species is limited, producing
competition.
Wallace and Darwin both realized that these factors suggest that species with characteristics that compete
better are more likely to survive and reproduce. If these characteristics are heritable then they are likely to
appear in the coming generations of that species.
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 evolution bottom line is not based on physical fitness instead it is based on reproductive success.
Physical fitness would more likely be a factor towards reproductive success.
The 2 aspects of natural selection that are important to determine whether an individual would be
reproductively successful are:
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Roshan Singh
10/18/07
Mr. Joordens
PSYA01H3
Chapter 3 Notes
VariationThe differences found across individuals of any given species in terms of their
genetic, biological (size, strength, physiology), and psychological (intelligence, sociability,
behaviour) characteristics.
CompetitionA striving or vying with other who share the same ecological niche for food,
mates, and territory.
Factors responsible for these sorts of variations
GenotypeAn organisms genetic makeup. As it differs from other individuals except for
identical twins
PhenotypeThe outward expression of an organisms genotype; an organisms physical
appearance and behaviour. As it also differs from other individuals as well.
The phenotype is determined by the interaction of the genotype with the environment and basically it
determines how much of the environment can influence on organisms development and behaviour.
Grants study has 2 important points (finches with big and small beaks):
Even though, evolution occurs in the long run, natural selection can produce important changes in
the short run i.e. within a few years
Phenotypic variation can produce important selective advantages that affect survival.
Competition also occurs between species when members of different species vie for similar ecological
resources such as food and territory.
Speculation that an early hominid named Ardipithecus ramidus might have lived 4.4 million years ago in
Africa (Ethiopia). It was not clear as to how human this creature was. 2 later species, Australopithecus
anamensis and Australopethicus afarensis were clearly like us because both of them exhibited bipedalism.
BipedalismThe ability to move about the environment upright on 2 feet.
3 to 3.8 million years ago species still shows signs of an ape like ability to climb trees. Over the period
from 3 to 2 million years ago, the hominid line split into 2. (Strait, Grine, and Moniz) It suggests that
maybe the African environment may have turned drier, altering sources of food. One line of hominids
evolved into a genus with powerful jaws that could crush and chew plants and nuts. They comprise the
genus Paranthropus. The other line continued from Australopithecus. But, around 2.5 to 1.8 million years
ago, 2 very distinct new species had evolved from this line, Homo rudolfensis and Homo habilis. Homo
habilis means handy man as this species was thought to be the originator of many stone tools.
EncephalizationIncreases in brain size.
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