Transcript Darwin`s Theory

Evolutionary Basis of
Stratification
Kim Freire
Daniel Adkins
March 1, 2004
Presentation Outline
• Basics of evolutionary theory and sociobioloy
• Evolutionary basis for gendered minds
• A gendered perspective of cultural evolution
• Lopreato’s summary: sociological implications
Basics
Evolutionary terminology and
concepts
Darwin’s Theory (1859)
1.
Species reproduce faster than the corresponding
resources can maintain.
2.
Hence, populations must cope with resource scarcity.
3.
Scarcity causes resource competition within or between
populations; called “the struggle for existence.”
4.
Some individuals are more successful than others in
struggle, and therefore reproduce more often.
Darwin’s Theory (continued)
5.
Differential reproductive success is caused by variations
in genetic endowments.
6.
Some variations are better adapted than others for
competition; offspring are more likely among better
adapted individuals/populations.
7.
The preservation of favorable variations and elimination
of unfavorable variation – natural selection – is due to
differential reproduction.
8.
Species transformation (diversification), via natural
selection, leads to the creation of new species.
Evolution
• “Descent with modification”
• The process is uniform across species and ecological
systems
• Transformation: change in gene frequencies
(microevolution)
• Diversification: introduction of new genetic material
(macroevolution)
Three Evolutionary Processes
• Natural Selection: preservation/elimination of
favorable/unfavorable variation
• Heredity: the transmission of qualities from ancestor to
descendent through genes
• Mutation: modification existing genetic material
Sociobiology
History and Basic Concepts
Modern History of Sociobiology
• Recent “field” of study, although many core concepts
derive from the work of Malthus, Mendel and Darwin.
• A synthesis of ideas – rather than one theory - from
multiple disciplines, particularly biology, anthropology,
psychology and sociology.
•
Many individual contributors; we’ll only name a few that
represent biological, cultural, cognitive studies.
The Naturalist
• American biologist, Edward O. Wilson: wrote
Sociobiology, published in 1975.
• Synthesized work of other scientists, such as Robert
Trivers and Richard Dawkins (“The Selfish Gene”).
• Wilson also extracted ideas from his own work with ants, a
member of the order Hymenoptera: “social insects.”
The Anthropologists
• Napoleon Chagnon’s studies of the Yamamano people
(“The Fierce People”) correlated aggression with
reproductive success.
• Anthropologists John Tooby and Leda Cosmides coined
the term “evolutionary psychology” to neutralize conflict
regarding biological basis of inequality.
The Cognitive Linguists
• Noam Chomsky and Steven Pinker weigh in from a
cognitive-linguistic perspective of human nature.
• We know too little about core human capacities to make
any final judgments about the validity of genetic vs.
cultural theories of human behavior.
Basic Concepts of
Sociobiological Theory
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Natural and sexual selection
Phenotype/genotype
Kinship
Altruism/Selfishness
Differential Parental Investment
Fitness
Adaptation
Aggression
Competition
Evolutionary Sex Differences
• All human societies have distinguished the sexes by their
anatomy and behavior.
• Both socialization and biology affect patriarchal social
arrangements.
• Key question: Is patriarchy the cause or effect of sex
differences?
An evolutionary basis for
gendered minds
Steven Pinker
and
Margo Wilson and Martin Daly
Theoretical Background
• Common theoretical underpinning to both
of these readings:
Trivers (1972) Theory of Differential
Parental Investment
- If one gender is more invested (in terms of time,
energy, and resources) in their offspring, this will
lead to different selection pressures between the
sexes.
Elaboration
• Human women must invest a minimum of 9
months pregnant, A man…30 minutes (a generous
estimate).
• This difference will lead sexes to pursue very
different reproductive strategies: men being less
selective in choosing mates and females being
highly selective.
• In this scenario women are the limiting factor in
reproduction, thus men will tend to compete for
their “affections”
Dominance-seeking monkey-brained
men
• This intra-sexual competition between men
leads to:
• Physical dimorphism in which males are larger than
females. Size does matter… at least in dominating sexual
competitors.
• Psychological dimorphism, in which males will be more
prone to seek status, wealth, and power in efforts to
enhance their reproductive attractiveness to females.
Nurturant females
• Among all animals in which females invest
more calories and risk (than males) in each
offspring (i.e.-pregnancy and nursing in the
case of humans), females also tend to invest
more in nurturing the offspring.
• Thus, among females, traits associated with
being effective caretakers are often selected
for.
Pinker’s Arguments
• Pinker’s intent is more general as he is
seeking to establish that sexes have
behavioral and physiological differences (in
terms of population means), which are
genetically based.
Pinker’s evidence
• Pinker cites numerous “natural experiments” in which
children genetically of one gender were raised the other
and eventually came to identify as their true gender.
• All human cultures share a sexual division of labor and the
belief in different “natures”.
• Mitochondrial DNA (inherited from Mom) tends to be
more diverse than Y chromosome DNA (from Dad)
• Androgens (e.g.-testosterone) have definitively been
shown to associated with aggression, libido and selfconfidence. They also have permanent, masculinizing
effects on the developing brain.
Brain Differences
• There are differences in brain anatomy.
• Hence, there are differences in cognition, sensation and
emotion.
• Male aggression is a mammalian adaptive trait related to
fitness, which can be intensified or mitigated via
socialization.
• Key question: To what extent are differences biologically
vs. socially defined?
Feminism and Sociobiology
• Sociobiologists and “radical” feminists agree that:
– men seek to control women
– patriarchal systems burgeon from males perceived need to control
women
• However, these perspectives diverge in their rationale of
domination: sexual selection vs. desire for power
• The most radical branch of feminism rejects the biological
basis of sex/gender.
Wilson and Daly’s Argument
• Building on Trivers, the authors assert that males
in competition for mates will tend to maximize
their reproductive chances by seeking monopolize
females.
• Humans reproduction is characterized by
biparental care and internal fertilization. Which
increases both the costs and likelihood of
cuckoldry. Thus there are strong selective forces
for ensuring one’s paternity of ones putative kids.
Evidence
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Swallows and Dunnocks
Strict female monogamy not likely historically-testes size
Harems
Jealousy: normal reaction
Differential care to genetic and step children
Adultery: generally defined as a female act often legally
punishable
A gendered perspective of
cultural evolution
Rae Lesser Blumberg
Retreat to an Utopian Past
• This piece is somewhat dated; however, it
raises interesting points about the female
relationship to power and production in
societies.
• Most of its points concern CULTURAL
evolution (à la Lenski); thus we will only
discuss a few salient points.
Blumberg: The pliability of gender
relations
• Aside from its value as a historical document
illustrating the social constructivist paradigm of
the 70’s, this piece is valuable because it illustrates
variation in female status across societal types.
• The implication being: even given geneticallybased cognitive and behavioral sex differences,
women’s roles in society are incredibly plastic
depending on social structure.
Toward causality
• Blumberg attempted to locate the crucial
causal mechanism influencing females’
status.
• She finds strong parallels between female
empowerment and women’s relation to the
means of production…
The Origin of Material Inequality
• Sharing: occurs mostly in absence of surplus
• Surplus: changes family structure; inheritance
emerges
Environmental “Lushness”
• Abundant and reliable food sources – as well as other
resources – facilitate more complex family structures.
• This family extension – beyond a nuclear unit - leads to
less group sharing and increases sedentism, which leads to
surplus.
• Inheritance systems emerge.
Cultivation
• Internal and external population pressures create a need for
more food.
• Planting occurs.
• Women enlist their children to help grow food.
• Resource scarcity and population pressure leads to class
stratification.
Sexual Stratification
• What is the degree of female power relative to males of her
group?
• To what extent do females approach equal treatment and
opportunities with the males of her group?
Women and Power
• Lenski’s power schema: property (i.e., economic),
position, and force
• Females may have economic power in some groups, but
males monopolize the latter two dimensions.
• Women’s relative economic power is the primary
determinant of the relative equality of men vs. women in a
group.
Female Economic Power
• Weber’s definition of power is the foundation.
• The extent of women’s control (relative to men’s) of
production means and surplus distribution.
• Begins with labor production and can lead to land and
capital.
Female Participation in Production
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Two key factors:
1) Economic activity’s compatibility with child care
responsibilities.
2) The supply of male labor relative to demand
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Other “poker chips”:
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Strategic indispensability
Kinship system
Men’s participation in child-rearing
Male superiority ideology
“Life Options”
In Summary: Female Paradigm
1) Power is most affected by control of production means.
2) Strategic indispensability is essential.
3) Kinship arrangement facilitate economic power and
mitigate force.
4) Females are most oppressed when they have little or no
economic
power.
5) Females can translate relative economic power into greater
life options.
Industrialization and Capitalism
• Commodification of land and labor
• Women increasingly participate in labor production and
fertility rates decrease.
• Key question: How has industrialization/capitalism
affected sexual stratification?
Lopreato’s Summary
• Current social stratification theories lack an
evolutionary perspective.
• The failure of destratification efforts may be
explained by evolutionary theory.
• Theory development requires a set of propositions
to debate and empirically test.