Biological and Social Evolution
SOC 370: Social Change
Dr. Kimberly Martin
Evolution is change through time.
Parallel Evolution – similar changes through time without
any coordination or contact between changing entities
(people, societies, animals, plants, etc)
Divergent evolution – the same or similar entities that grow
more and more different from each other over time.
Convergent evolution – different entities that grow more
and more similar to each other over time.
ALL EVOLUTION IS ABOUT ADAPTATION
Patterns of Evolution
• Gradualism – the idea that evolution is always a
slow and steady process that takes a long time.
• Equilibrium (stasis) – a period of time when
there is no change
• Punctuation – a short burst of rapid change
• Punctuated equilibrium – periods of gradual
change interrupted occasionally with bursts of
rapid change.
• Extinction – the loss of types of biological or
social phenomena over time
Kinds of Evolution
Biological Evolution
based on changes in the genetics of
populations which alters their potential to
develop adaptive characteristics.
SocioCultural Evolution
based on changes in behavior patterns,
social relationships, values and beliefs that
happen in human populations.
THIS COURSE IS ABOUT SOCIOCULTURAL
EVOLUTION
Course Focus
• Why look at biological evolution in a
course on sociocultural evolution?
– Many people confuse how biological and
sociocultural evolution work
– Confusion has resulted in serious
ethnocentric errors about what humans are
like.
– A clear understanding about the differences
between biological and sociocultural evolution
helps to avoid these kinds of errors.
Biological Evolution
• Biological evolution is a change in gene frequencies in a
population over time.
• Biological evolution does not occur in individuals. It
occurs in populations.
• Biological evolution occurs as individual members of a
population adapt more or less successfully to particular
environments.
• Success in biological evolution is measured by the
number of one’s genes that are passed on to
subsequent generations.
• Those individuals who adapt well will have more and
more successful offspring, and will pass more of their
genes on to future generations than individuals who do
not adapt well.
Biological Evolution
• Genotypes – the actual
genes that a person has.
• Vs
• Phenotype – the
characteristics that are
expressed in the physical
body or behaviors of a
person as a result of
genetic inheritance and/or
the interaction of genes
and environment.
Biological Evolution
• The numbers of a given gene in a population
can increase or decrease in just a few
generations.
Four Forces of Evolution
Changes in gene frequencies over generations
happen in one of four ways:
1. Mutation – changes in the genes themselves
2. Migration – changes in gene frequencies when
individuals join or leave a population taking
their genes with them
3. Natural Selection – changes in gene
frequencies when the phenotypes from the
gene help or hinder adaptation
4. Genetic Drift – when individuals do not
reproduce for reasons unrelated to their genetic
makeup
Mutation
• Mutations can be spontaneous or caused
by a mutagenic agent.
• They happen at a very low rate
spontaneously (eg. 5 in 1 million).
• They are the only source of new genetic
material.
Migration
• When people migrate to a new location and join
a new population, they bring their genes with
them, changing the proportions of genes in their
new group or adding new genes to the
population’s gene pool.
• When they leave a population, they take their
genes with them, and so change the proportions
of genes available to be passed on to future
generations in the old group.
Natural Selection
• Is defined as “differential reproduction based on
the adaptive value of genetically based traits”
• Individuals who are better adapted to the
group’s environment will have more offspring
who will survive to reproduce themselves.
• Individuals who are less well adapted to the
group’s environment will have fewer offspring
who will survive to reproduce themselves.
• Offspring carry genes into future generations.
Genetic Drift
• Genetic drift occurs when individuals fail to
reproduce for reasons that are not related
to their genotype.
• They fail to pass their genes on to future
generations (or pass fewer genes on) in
ways that are not systematically patterned
by the adaptive value of their genes.
Co-evolution
The interaction of biological and
socio-cultural factors that causes
change through time.
Eg. The reduction of tooth size in humans
that corresponds to increased use of
tools to cut food and the cooking of
food.
Eg. Lactose tolerance in pastoralist groups.
Eg. Chewing coca leaves at high altitude in
Peru.
Socio-Cultural Evolution
• Can be much more rapid than biological evolution
because it does not have to wait for generations to pass.
• Can occur in any part of social or cultural life, including
ideology and religion, technology and economics, family
and social relationships, or art and aesthetics.
• May involve moving from one level of complexity to
another.
• May be called progress if it is perceived to be moving
from lower levels of complexity toward higher levels of
complexity.
• Is made up of the choices and behaviors of individuals,
but manifests itself as changes in the norms of groups
Social Darwinism
• Those who “succeed” or “progress” in society are well
adapted and have a right to survive and reproduce.
• Those who do not “succeed” in society are not well
adapted and should not be helped to survive and
reproduce by those who do succeed.
• Those who “succeed” have a morally justifiable right to
dominate those who do not “succeed” to maintain their
status.
• “Progress” is defined as living in a “complex, urban
civilization” by those who live in a “complex, urban
civilization”.
• “Success” is defined as the accumulation of wealth and
power by those who have accumulated wealth and
power.
Social Darwinism
Areas where Social Darwinism has impacted
world systems
• Colonialism
• Racism
• Corporate Globalization
The 19th Century Evolutionists
Modern Culture Change Theories Began with:
Edward Tylor and Henry Morgan
Three stages through which all civilizations have
passed, with some societies not progressing
past one or another stage
1. Savagery
2. Barbarism
3. Civilization
(Biased data and ethnocentrism)
What is Progress?
• Sanderson uses the term “teleology”, which means that change is
aimed at a predetermined goal or result. It is directional change.
• Progress implies that change brings improvement.
• The concepts teleology and “progress” directional change are
common assumptions when thinking about evolutionary change.
• These ideas are androcentric (biological evolution) and ethnocentric
(sociocultural evolution).
• The best adapted species? The species that integrates best into an
ecosystem? The species most successful in reproduction?
• The one with the most toys wins? Quality of relationships?
• Hunting and gathering societies work and leisure time ratios
• Diet and nutrition differences between hunting and gathering and
agricultural societies
Unilineal vs Multilineal Evolution
Neo-Evolutionism in the 1950’s
• Leslie White – unilinear evolution
change based on the efficiency
(technology) with which a society
harnesses energy
• Julian Steward – multilineal evolution
each society has a particular path by
which it has changed through time
• Marshall Sahlins – general vs specific
evolution
Devolution or Collapse
• Part of socio-cultural evolution
• The regression of a society to a previous,
less complex level of organization
• Is NOT a regime change (which is a
change in personnel, not a change in the
social structure)
• Best examples are the collapse of the
Roman, Mayan and Zapotec empires.
Study Guide
Parallel evolution
Convergent evolution
Divergent evolution
Gradualism
Equilibrium
Punctuation
Punctuated equilibrium
Extinction
Biological evolution
Sociocultural evolution
Mutation
Migration
Natural Selection
Genetic drift
Genotype
Phenotype
Co-evolution
Social Darwinism
19th Century evolutionists
Progress
Biased data
Ethnocentrism
Savagery
Barbarism
Civilization
Neoevoltuion
Unilineal evolution
Multilineal evolution
General evolution
Specific evolution
Devolution
Collapse