Learning Center
Plans & pricing Sign in
Sign Out
Get this document free

Problems of Kinship


									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?               
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

What about social justice?
What about adoption?

To top