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Problems of Kinship


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									Who are you?

   Write down the first 10
   descriptions of yourself
   that come to mind. Try to
   work as quickly as
Problems of Kinship

What is Family?
Defining Family

Emlen (1995) described two types of families:
  simple families & extended families
both of these definitions hinge on the presence
 of a reproducing female
  What about homosexual couples?
Only 3% of all bird and mammalian families live
 in family groups
living with families is detrimental to
The Evolution of Families

Ecological Constraints Model
Familial Benefits Model
Conditions necessary for the evolution of
  more offspring than reproductive vacancies
  offspring must wait for reproductive vacancies until
   they have the required attributes to compete for
   mating positions
  benefits of staying with the family must be large
Predictions of Emlen’s
Regarding kinship and cooperation
  shortage of reproductive vacancies
  more resources, more stable families
  more assistance in child-rearing in families
  sexual aggression is low
Regarding changes associated with the
 elimination of a breeder
  conflict concerning the appointment of a successor
  breeder who is not genetically related will increase
   sexual aggression
clip: Steven Pinker
Origin of Kinship Altruism

Reciprocity demands familiarity
in ancient times, familiarity meant kinship
kinship altruism = manifestation of
 reciprocal altruism
How far-reaching are the effects?
  Inuits = strongest non-kin relationship <
   weakest kin relationship
  understanding among non-kin
Studying Kinship

Families are more difficult to study than
extended families don’t live near one
favoring kin seems normal
nepotism challenges Western principles
Inclusive Fitness Theory

 An individual’s own reproductive success plus
  the reproductive success of relatives as weighed
  by the degree of genetic relatedness
Altruism - a behavior that results in costs to the
 self and benefits another
Hamilton’s Rule:
                       c < rb
  c = cost to individual
  r = degree of genetic relatedness
  b = benefit to other person
Genetic Relatedness
Identical twin = 100%
Sibling = 50%
Parent = 50%
Grandparent = 25%
Aunt/Uncle = 25%
Cousin = 12.5%
Great Aunt/Uncle = 12.5%
Great Grandparent =12.5%
Hypotheses about Kinship
(from Daly, Salmon, & Wilson, 1997)

Ego-cetered kin
Distinctions regarding
Distinctions regarding
“Closeness” associated
 with genetic relatedness
Hypotheses about Kinship
(from Daly, Salmon, & Wilson, 1997)

Elder members will encourage altruism
 towards collateral kin
  clip: “Gilmore Girls”
Position within kin network becomes a
 part of self-concept
People know who their “real” kin are
Kinship terms produce illusory feeling of
 connectedness between unrelated people
Alarm Calling in Squirrels

Alerted squirrels benefit, but
 the alarm caller is in trouble
potential explanations:
  predator confusion hypothesis
  predator deterrance hypothesis
  reciprocal altruism
  parental investment
  inclusive fitness hypthesis
can these findings be applies
 to humans?                         http://www.agpix.com/catalog/AGPix_Read/
Helping in Humans

A study of 300 women in Los Angeles
  more likely to help closely related kin
  more likely to help those with greater
   reproductive value
Hughes (1988) used mathematical
 analysis to show that key individuals in a
 society are those who have just passed
 through puberty
  now able to reproduce
Helping in Humans

Fieldman et al. (submitted) asked
 subjects to sit in isometric position
 for cash reward
performed on successive days
recipient of reward changed with each
length of time subjects were prepared to
 endure pain proportional to genetic
 relatedness of recipient
Life-or-Death Helping
study by Burnstein et al. (1994)

Two types of helping:
  substantial helping
  trivial helping
Two scenarios:
  burning house and must save one person
  run errands for someone
Life-or-Death Helping
study by Burnstein et al. (1994)

Helping decreased as genetic relatedness
  especially strong effect in life-or-death scenario
Helping in life-or-death scenario decreased with
  effects of age reversed in trivial scenario
Helping is a function of genetic relatedness and
 Why were one-year-olds helped the most?
Life-or-Death Helping
 Clip: “The Pretender”
 Expansion on Burnstein et al. (1994)
   measure of emotional closeness
 more likely to be emotionally close
  with more related kin
 emotional closeness correlated with
  altruistic behavior
    Are these constructs really as different as
     Buss makes them out to be?
                                                   Kitty Genovese
 having kin in close proximity during
  life-or-death situations affects
  survival rates
    Mayflower and Donner party
Parent-offspring conflict
Sibling conflict
siblings can be strong
 social allies, but also
 represent competition
 for parental resources
  clip: “In Her Shoes”
adaptive problem for
  clip: “Narnia”
Sulloway, 1996

In all societies, parents discriminate
 among their children
Adaptive problems create niches based on
 birth order
  oldest child: support the status quo
  middle child: continually trying to surpass
   older children
  youngest child: most likely to be spoiled
     clip: “Narnia”
(from Sulloway, 1996)

Strategies siblings
 use to procure
 parental resources
  promote parental
   favor directly
  dominate their rivals
  counter domination
How does this relate to your experiences
  with siblings?
Patterns of Inheritance
Three predictions:
  genetically related kin &
  closely related
  offspring rather than siblings
study of 1000 randomly
 selected decendents in
 British Columbia
  recorded dollar value of estates
  labeled beneficiaries by genetic relatedness +
   “spouse” and “nonfamily”
Patterns of Inheritance

 Women distribute wealth to more people
   men leave everything to their spouse
   women did not trust men to distribute wealth
   older men remarry more often than older women
      may divert wealth from decedent to new offspring rather than
       shared offsrping
   older women are usually postmenopausal
 92.3% wealth to spouses or family
   46% to relatives sharing 50% genes
   8% to relatives sharing 25% genes
   less than 1% to 12.5% of genes
 Four times as much to offspring than siblings
Investment by Grandparents

Genetic relatedness =.25
Two generations of paternity
order of investment:
  Mother’s mother
  Mother’s father
  Father’s mother
  Father’s father
     clip: “Gilmore Girls”
Investment by Grandparents

 Discriminative grandparental
  investment theory
 DeKay (1995) confirmed
 Euler & Weitzel (1996)
   results confirmed hypotheses
   MoFa being higher rules out sex
   ruled out differences due to
Grief: A Measure of Selection
study by Littlefield & Rushton (1986)

Examined magnitude of grief when a child
   loss of inclusive fitness prospects
Self-reported measures of grief
Parents grieved more than distant
age and health of child
differences in grandparents’ grief
Final Discussion Topics

Altruism as an explanation for
   http://video.google.com/videoplay?docid=665607106454961127&q=altruism

What about social justice?
What about adoption?

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