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Lecture 2

Week 2

Course Code
Marc A Fournier

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Week 2 Lecture:
Human Evolution
Overview of Week 2 Lectures
Part I. The Structure of Evolutionary Theory
Part II. The Attachment System
Part III. The Rank System
Overview of Part I
The Evolutionary Process
Products of the Evolutionary Process
Personality as a Product of the Evolutionary Process
The Evolutionary Process
-The three basic elements of the evolutionary process:
Variation the idea that organisms vary in our design features (skinny/larger,
Inheritance not all but some of these design features are inheritable; passed on to
some extent to their progeny; acquired features dont pass on but the ones that have
genetic bases; if environmental challenges stay the same over a long period of time,
those traits that equip organisms to survive will become so frequent that they
become typical of the species that virtually all members of the species will have the
Selection the idea that design features, to a greater or a lesser extent, can
influence our capacities to survive and reproduce; and if these design feature can be
passed on and can contribute to our survival and reproductive success then those
traits will appear in greater frequencies in future generations
-The evolutionary theory traces back to Charles Darwin
-Any psychological theory must be consistent with evolutionary theory if we imagine
it to be correct, therefore so does any personality theories
Natural Selection
-Is one of two evolutionary processes that Darwin imagines
-It is the evolution of adaptive characteristics b/c of the survival benefits bestowed on
those having them
-The long neck of the giraffe is the product of natural selection pressures the longer
necked giraffes had the greatest reach for food as a result survived and reproduced

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successively; with each successive generations giraffes with shortest necks survived
and reproduces less frequently and neck length has genetic bases and over
generations there was an increasing frequency of long necks and now it is
characteristic of the specie
-The trait is contributing to the survival of the species
Sexual Selection
-At the same time of working on the natural selection theory, Darwin was struggling
with a troubling observation that there were traits that some species seem to have
and they seem to be functional at the very least to the species but they also seemed
to be selected by natural selection
-Ex: Peacock’s tail; why would they be selected when it makes them vulnerable
to predation
-Sexual selection is the evolution of adaptive characteristics b/c of the reproductive
benefits bestowed on those having them
-They may even be selective for in spite of the fact they impact survival negatively
Intrasexual Competition
oe.g., stags antlers the larger the antler the better equipped to fight and the
more equipped to secure mates; saying this trait is heritable then more
successful males with large males will pass it on to male offspring
-same sex competition
-it capitalizes on the observation very frequently in the natural, members of one sex
will compete with each other for access to the opposite sex
-Quite frequently, we will see that it is the male of the species that are in competition
for access to female
-Those traits that enable one to compete successfully against ones own sex will
therefore be ensured that that male reproduces more successfully and it that trait
has inheritable bases then the offspring will have those traits as well
Intersexual Selection
oe.g., peacocks plumage
-often males are competing against each other for the access of mate (intrasexual
competition) while females are in the position to choose their mates
-if the female population has a consensus of whats desirable in the males of the
species, those males that have those traits will be chosen as mates more often and
they will reproduce successfully more often and those desirable traits will be passed

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Products of the Evolutionary Process
oThree products most frequently mentions: adaptations, spandrels & random
Adaptations (Evidence of Special Design”)
-Are those design that are selected and coordinated toward solving recurrent
-Often have the feature of being species typical (all members of species have them)
-Those features that contributed to the survival and reproductive success
-Ex: Ears
Spandrels (By-Products”)
-Are design properties that do not directly contribute to adaptation
-Rather they are linked at a genetic level to adaptation so they get carried along the
evolutionary process
-So they become incidentally incorporated into the design of an organism
-Ex: Ear lobes (by-products of adaptations the ear)
-Doesnt mean they will have a functional significance or adaptive value; correlated
with something that is adaptive
Random Effects
-Noise in the system
-Refer to design features that are adaptively neutral
-Vary subtly in the species (size and shape of the ear)
-Dont contribute to the functionality of trait
-They get passed along b/c they are adaptively neutral
Species-Typical shared by all members of the species
Suspiciously Functional the design feature is complex that it is efficient and
specialized towards solving some particular problem or set of problems
-Ex: There is a suspicious coincident between the functional design of giraffes and
where they happen to obtain their nutrition
-We recognize adaptations b/c of their suspicious functionality that they seem to have
been uniquely configured to solve problems the species face
They serve as condensed records of ancestral conditions
-The traits we have that are adaptation are interesting window into evolutionary time
b/c they give us a sense of the recurrent adaptive problems that are ancestors
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