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 Evolutionbased on changes in the genetics of

populations which alters their potential to develop adaptive characteristics.

SocioCultural Evolutionbased 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 themselves2. 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 GuideParallel evolution Co-evolutionConvergent evolution Social DarwinismDivergent evolution 19th Century evolutionistsGradualism ProgressEquilibrium Biased dataPunctuation EthnocentrismPunctuated equilibrium SavageryExtinction BarbarismBiological evolution CivilizationSociocultural evolution NeoevoltuionMutation Unilineal evolutionMigration Multilineal evolutionNatural Selection General evolutionGenetic drift Specific evolutionGenotype DevolutionPhenotype Collapse