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Chapter 10

PSYCH 3T03 Chapter Notes - Chapter 10: Vasopressin, Tioga Pass, Hypoglossal Nerve

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Sigai Balshine

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Chapter 10: Proximate and Ultimate Causes of Behaviour
Ultimate causes of behaviour is a perspective on the adaptive value and history of a trait
of interest
Proximate causes of behaviour is a perspective that analyzes the mechanisms underlying
behaviour including the development and neurophysiology
Connecting the four levels of analysis
o The four levels of analysis (physiological systems, developmental systems,
adaptations by natural selection and evolutionary history) are linked together
because behaviours that have positive effects on fitness have proximate,
underlying behaviours
The proximate and ultimate causes of monogamy in prairie voles
o The behaviour of monogamy has been studied in prairie voles from all four levels
of analysis. It is thought that monogamy is a puzzling situation since
monogamous males are losing valuable additional opportunities to mate and pass
on genes
o One hypothesis for male monogamy is that this increases the chance that the male
will father all of the female’s offspring (mate-guarding hypothesis)
♣This is an adaptionist perspective
o Another ultimate perspective observes that prairie vole ancestors were previously
polygynous and their behaviours were modified to be monogamous
o Cells in prairie vole brains have protein receptors that bing chemically to a
hormone vasopressin, which is released when a male copulates many times with a
female. Molecules of vasopressin are carried to the ventral pallidum, a structure
associated with providing rewarding sensations upon completing behaviours. This
structures receptors (called V1a receptors) are stimulated by vasopressin that once
binded, activates neural pathways in the brain associated with positive feedback
for mating behavior. This influences a male to remain in a long-term relationship
with it’s copulatory partner.
o The V1a receptor protein is encoded by avpr1a gene, which has a chunk of DNA
that is missing in the same DNA component found in polygamous voles

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♣There is also a school of thought suggesting that females prefer this extra
chunk of DNA, pulling in female preference for monogamy as being
♣Genetically adding more of this genes resulted in more eagerness in males
to be monogamous
The proximate causes of bird song
o One hypothesis for different dialects in bird song of white-crowned sparrows in
Marler and in Berkely is that they differ genetically but there is little genetic
o Another hypothesis was that the social environments of these birds mattered and
to test this, they took bird eggs of sparrows and raised them in isolation, the result
being that at 150 days, very minimal singing. When the birds were hatched and
lkistened to a Marler tape, they sang to the dialect of a Marler and when listening
to a Berkely tape, they sang to the dialect of a Berkely sparrow. Overall, hearing
neighhbouring birds affected the development of dialects
o Being able to hear itself sing is critical for a baby bird
o When a young white-crown bird is exposed to another species song such as a
sparrow, they don’t develop that type of song or dialect, listening to other birds
does not influence it’s behavior
o Social Experience and Song Development
♣At a young age, white-crowns are able to selectively store information
about songs mde by white-crown while effectively ignoring other species
♣Then, when the bird is starting to sing, it will access it’s memory for the
other white-crowns and when it begins it’s plastic song, it compares with
the songs in memory and adjusts accordingly to create full songs
This is a proximate perspective
♣However, social acoustical experience also matters as white-crown will
learn other species songs if they can hear and see their tutors and even
when they can hear their own species song
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