Adaptiveness of Behavior

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Adaptiveness of Behavior

• Genetics and evolution
• Learning

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Evolution in a nutshell

• Start with variability in genes, and thus in
  traits
• Add challenges the world poses to survival and
  reproduction
• Result
• genes/ traits that decrease chance of
  reproduction get reduced in next generation
• genes/traits that increase chance of reproduction
  get increased in next generation

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Functionalist perspective

• Physical and behavioral traits come about in the
  course of evolution because they promote survival
  and reproduction
• Thus there must be a functional explanation for
  every trait/ behavior

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Functionalist perspective

• Caution
• vestigial traits
• traits as side effects of natural selection
• chance variations (genetic drift)
• Some traits do not serve an immediate function,
  but they wont killya!

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Functionalist perspective

• Caution
• Survival of the fittest-- misconception of
  natural selection as guided by moral force
• term coined by Spencer, not Darwin
• Misconception leads to Naturalistic Fallacy
  belief that natural right, moral that if
  natural selection favors a behavior, that
  behavior must be acceptable
• Examples?

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Environment and evolution

• What is the color of the peppered moth?
• pre-industrial revolution trees covered with
  light-colored lichen
• air pollution killed lichens, trees became dark
• anti-pollution laws cleaned up air, lichens grew
  back
• Other examples happening right under our nose?

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The Genetics of Behavior

• genes-units of heredity
• chromosomes-strands of genes come in pairs
• deoxyribonucleic acid-DNA
• ribonucleic acid (RNA)-template for synthesis of
  proteins
• roles of proteins??

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Mendelian genetics

• homozygous
• heterozygous
• dominant gene
• recessive gene

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Mendelian genetics
Traits caused by single gene - PTC taste -
Phenylketonuria - SLI - dogs fearfulness Variat
ions of type, not degree
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Polygenic Traits

• influenced by many genes
• Differ in degree, fall on continuum
• distribution described by normal curve
• selective breeding can change distribution

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Polygenic Traits
Eg maze learning
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Selective breeding

• Alcohol consumption in mice
• Anderson and McClearn (1981) measured ethanol
  solution intake by fluid-deprived mice
• Ratio of alcohol intake on test day/ to water
  intake on day prior to testethanol acceptance
  score
• mice with highest scores are mated, mice with
  lowest scores are mated
• 1st generation mean scores of high/ low group
  0.74 0.87
• 14th generation 0.38 1.19

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Genetic diversity, or How unique are you

• Humans have __ pairs of chromosomes
• Imagine you only had 1 pair. How many different
  individuals could you produce through sexual
  reproduction?

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Chromosome Pairs n1
M1 a b
D1 a b
Mom
Dad
You could get possible gametes from each
parent 21 2
or
from Mom and
or
from Dad
So you could be Possible genotypes 22 4
1 in 4
or
or
or
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Chromosome Pairs n2
Mom M1 M2 ab ab
Dad D1 D2 ab ab
You could get M1a/ M2a or M1a/M2b or M1b/M2a
or M1b/M2b from Mom AND D1a/ D2a or D1a/D2b
or D1b/D2a or D1b/D2b from Dad Possible gametes
from each parent___ You could be M1a/ M2a /
D1a/ D2a or M1/a/ M2a / D1a/D2b or M1a/ M2a /
D1b/D2a or .. Possible genotypes____
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Chromosome pairs n23

• Possible gametes from each parent 223
• Possible genotypes 246 more than 70 trillion!
• Does not include variation due to crossing over,
  mutations
• We are SO unique!!!

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However

• Guesstimate How many genes do we have?
• How many do bacteria have?

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relatedness- a closer look
M1 a b
D1 a b
Mom
Dad
You could get possible gametes from each
parent 21 2
or
from Mom and
or
from Dad
1 in 4
or
or
or
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relatedness- a closer look

• Refers to chance of sharing a particular gene
  with someone
• Does NOT refer to the total amount of genetic
  information shared between two individuals

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Species-typical behaviors

• Example 1
• red belly as sign stimulus for stickleback attack
• Example 2
• migratory flight in indigo buntings
• birds migrate at night
• Emlen (1975) birds caged outside make restless
  futile movements towards south in fall, north in
  spring

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Species-typical behaviors

• Question 1 How do they tell direction? What is
  their sign stimulus for migration?
• Question 2 Is knowledge innate or learned?
• Materials
• as many buntlings as you wish
• as many undergrads as needed to watch them
• several months of nothing better to do
• a planetarium

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Emlens deprivation experiments

• 1. Block view of sky
• 2. Block view of Polaris
• How do they know to use Polaris?
• 3. Raise buntlings in 3 groups
• group 1 no experience with night sky
• group 2 normal night sky
• group 3 fake sky with different fixed star
  (Betelgeuse)
• measured orientation of movements when exposed
  to normal sky in fall

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Emlens deprivation experiments

• Findings
• Group 1 no consistent orientation
• Group 2 away from Polaris
• Group 3 away from Betelgeuse
• Conclusion?