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Lecture 2

PSYB30H3 Lecture Notes - Lecture 2: Pair Bond, Pleistocene, Attachment Theory


Department
Psychology
Course Code
PSYB30H3
Professor
Marc A Fournier
Lecture
2

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Week 2: Lecture #2: Wednesday January 14 2015
The Evolutionary Process:
Variation: Variation in design, differences taller, shorter, better eyesight, poor eyesight,
cognitive ability.
Inheritance: Not all differences are heritable differences. Some differences are heritable.
Selection: Our designs impact our rates of reproduction. Differences in design influence
differences in reproduction.
Evolutionary Processes: Natural Selection
- Natural selection is the evolution of the adaptive characteristics because of the survival benefits
of those who have them.
Natural selection = survival.
Example: Giraffe benefited the giraffe in terms of survival of having the long neck.
“Species-typical”
Hypothesis of Darwin raised questions
Evolutionary Processes: Sexual Selection:
- Evolution of adaptive characteristics because of the reproductive benefits consoled of those
who have them.
Intrasexual Competition
o E.g. stag’s antlers
o Members of one sex compete for time of the opposite sex access to time and
sex.
o Usually male.
o Serve to compete with other males to gain access to other females.
Stag’s antlers
They have the antlers not for survival, but because of reproductive
advantage.
Intersexual Selection
o E.g. Peacocks’ plumage
o Survival is not important, but survival is important for reproductive.
o Longer you survive, more opportunities you have to reproduce.
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Products of the Evolutionary Process:
- Adaptation (“Evidence of Special Design”)
o Design properties selected and coordinated towards solving recurrent problems in the
environment.
Environments encountered by ancestors.
Tend to but not always, but species typical universal.
Examples: Giraffe, antlers of the stag.
Universal within species or gender.
o Spandrels (“By-Products”)
o Design property that does not directly contribute to adaptation but is linked to an
adaptation/adaptive properties, as a result, it gets incorporated into the design.
Similar features of an adaptation.
Typical of the species, because it is correlated with an adaptation.
Example: Human Ear universal, clearly adaptive/ Ear Lobes - no
adaptive value, ear lobes goes with ears. Ear lobes does not contribute
to survival, but because it is part of the Ear, then it is a by-product.
- Random Effects
Design properties that are adaptively neutral.
Variation in ear lobe and size, ear lobe variability (big ear lobes, small ear lobes)
adaptively neutral. Random variation. Does not affect survival.
Adaptations:
- Species-Typical
Universal
Shared by virtually everyone in that species.
- “Suspiciously” Functional
Example of the Giraffe
o Specialization and reliability non-arbitrary
- Condense Records of Ancestral Conditions
Testimony of the environments that our ancestors survived
Record
- Common Misconceptions assume that much is adaptation = optimal design.
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ADAPTATION DOES NOT EQUAL OPTIMAL DESIGN:
- Constraints on Optimal Design
Time Lags
o Solutions don’t occur overnight – takes generations of species to be exposed to a
problem before anything like a solution will appear.
o For the time it takes for adaptation to appear, the world can change, the
environment can change. What was adaptive in the ancestral environment is not
adaptive today.
o Example: Hedgehog
- Adaptation is only adaptive today only to the extent that the present day environment
resembles the ancestral environment. The historical environment that the adaption was chosen
for.
Local Optima
Local peaks of optimization
Always picking what is available to you.
May end up at a high point, but not the highest point on the mountain.
Example: Mountain climbing
Takes the step that is most beneficial evolution has to planning ability,
not a planning process.
Insufficient Variation
Example: X Ray vision must appear as a mutation first.
If it does not appear in the genetic history, it cannot become typical of the
species. And if it doesn’t show up, then it cannot be part of the species.
Etc.
Just because something is adaptive does not mean it is optimal.
Adaptation or Exaptations?
- Definition of an Exaptation (Gould, 1991):
A feature, now useful to an organism, that did not arise as an adaptation for its present
role, but was subsequently co-opted for its current function.”
E.g. an old part exploiting for a new purpose.
- E.g. the feathers of birds’ wings.
Adapted function = insulation
Exapted function = flight
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