Darwin and Evolution
•	Life
•	Sources of theory
•	The theory
•	Implications for psychology
Darwin’s Life
•	Distinguished family
•	Educated for medicine, then the ministry at Edinburgh, then Cambridge
•	Not quick but loved nature
–	Influenced by Segwick (Geology) and Henslow (botany)
•	Center of scientific ferment
•	Speculation about age of earth
Darwin and the HMS Beagle
•	Signed on in 1831 for short voyage
•	Survey East coast of South America
•	Ships naturalist and companion to Capt. Fitzroy
•	Explored interior of South America and then Galapagos Islands
–	Fossils of marine creatures in Andes
–	Tortoises and finches on Galapagos
Returned to England in 1836
•	Lived life of country gentleman
•	Wrote his theory as early as 1844 but withheld publication
–	Feared wife’s religious objections
–	And censure of community
–	Wanted more data
•	Famous as naturalist before evolution
•	Ill with mysterious intestinal ailment most of his life 
Publication of the Formal Theory
•	Origin of Species in 1859
•	Stimulated by similar theory by Alfred Russell Wallace
–	Wallace sent him manuscript
–	Darwin had both published
•	Descent of Man in 1871
•	Emotions
•	Child diary
Sources of the Theory
•	Previous notions of evolution
•	British empiricism and utilitarianism
•	Enlightenment notions of progress and mechanism
•	Observations
Previous Theories of Evolution I
•	Since Aristotle speculation that higher animals evolved from lower
•	Medieval Great Chain of Being
–	Relationship of a sort among species
–	Static and immutable
Buffon’s (1749-1804) Theory
•	species created in original act
•	But degeneration through chance factors
•	Right on role of chance
•	But backwards in emphasizing devolution
•	And essentially a Great Chain of Being conception
Erasmus Darwin’s (1731-1802) Theory
•	Charles Darwin’s grandfather
•	Species could be created
•	This occurred through a striving or implanted needs
•	Thus had notion of evolution
•	But wrong mechanism
Lamark’s (1744-1829) Theory
•	Animals evolve as response to environmental pressures
•	Had notion of evolution
•	But wrong mechanism
•	The idea of acquired characteristics
Resistance from Religion
•	Many natural scientists were also ministers
–	Seeking God in nature
–	And mostly deeply committed to creationist view – world was ~ 10,000 years old
•	Evidence against had accumulated
–	Geological evidence suggested long life for world
–	Fossil evidence
–	Breeders create new species of both plants and animals
The Philosophical Background
•	Darwin’s real forerunner was Hobbes
–	Humans are individual
–	And hedonistic/selfish
–	Competition and violence are essentials parts of human nature
–	Culture is an artifact, a veneer
•	After Adam Smith and a century of assimilating Newton competition was seen as a natural law
The Influence of Robert Malthus (1766-1834)
•	Economist upset by French Revolution
•	Therefore his theory proposed that nature did not lead to progress
•	The law of population
–	Population increases geometrically
–	Food supply linearly
–	Hence unless people exercised moral restraint people would die of starvation
•	Struggle for survival and survival of the fittest
Darwin’s Response to Malthus
•	Was struggling with his theory when he read Malthus in 1844
•	Struggle for existence provided the “engine” for evolution
–	Survival of fittest was important but not key
–	The key element was the reverse – those who are not fit die
•	And the idea that the unfit do not survive environmental pressures is essential
Evolution and the Victorian Idea of Progress
•	19th Century deeply conflicted about progress
–	As heir to Locke they believed it must happen and was a kind of natural law
–	But it also tended to upset the existing order
•	Hence how to reconcile importance of change with that of stability
Herbert Spencer’s (1820-1903) Theory of Evolution
•	During middle 19th widely thought to be greatest thinker
•	But reputation has fallen on hard times because of social Darwinism
•	Passionate believer in a natural science of humans as key to progress
•	Had theory of human evolution before Darwin
Spencer’s Ideal of Progress
•	Progress was a natural law as people adapted to an ever changing world
•	The laws were given by nature which dictated which societies would rise and fall
–	Laws control
–	Therefore evolution is like Lara Croft who can win or lose battles but cannot change her narrative, her course
Conflicts Between Progress and Order
•	Often at odds, and major Victorian concern
•	Progress is inevitable
•	Order requires that people know their place
–	Natural laws assign places based on race, class, and gender
–	Hence “higher orders” are responsible for progress
–	Violations of natural order are violations of law
Social Darwinism
•	Spencer was generally a progressive on many issues
•	But also believed that social classes, races, and genders were placed where they were because of laws of nature
•	Hence the rice were by definition the most fit to survive
•	And social policy should not interfere with laws of nature
•	Remains basis of much conservative thought although disguised because of political correctness 
Darwin’s Observations
•	Succession of types
–	Fossils of extinct animals
–	But similar to existing ones
•	Representative species
–	In adjacent areas there are similar but distinct species
–	Each adapted to its niche
Observations on the Galapagos Islands
•	Climate identical but animals differ
–	Previous theories of evolution could not explain
–	Slightly difference physical environments
•	Hence speculated that each species had evolved to particular environments
Observations and Theory
•	Quickly assumed that species had evolved from one another
•	But lacked mechanism
•	Major mechanism is that selection kills off those who are less well adapted -- Malthus
•	But later saw positive mechanism by favoring those with certain features
•	No knowledge about genetics
–	Sometimes Lamarkian
–	Children have blends of parental features
The Theory – Natural Selection
•	Quite simple
•	Animals compete
–	With one another for food and other resources
–	Also a kind of competition or response to environments
•	Individuals with certain features will live longer
–	If features are genetic
–	Will be passed along to offspring
The Theory – Sexual Selection
•	Animals compete for breeding privileges
•	Those who are most successful
–	Have features preferred by females
–	Or other features that give better access
•	Strength
•	Smarts
•	Hence some animals will have more offspring and pass along features that are genetic
The Theory – Mechanics
•	There is no guiding principle – most important part of theory
•	Chance is key
–	Genetic mutations
–	Environments change
•	So no purpose or goal to evolution
•	Criterion of biological success is number of genes passed along
Subsequent Modern Theories 
•	Accounting for altruism
–	Kin selection
–	At level of group
•	Evolution of genes
–	Genetic drift – not Darwinian
–	Sexual selection and battle of sexes
Implications and Influence
•	Immediately successful
•	By bringing humans fully into the natural world
–	Made human behavior lawful
–	If only at a statistical basis
•	Fulfillment of the  Enlightenment program
•	And influential throughout society and various intellectual areas
Implications for Psychology – The Bad
•	Gave support to racism and sexism
–	Darwin ambivalent about race and sex differences
–	But most assumed that non-Whites were evolutionarily inferior
•	Eugenics
•	Instincts became dominant explanation
–	Functional analysis
–	But 20,000?
Implications for Psychology – Importance of Animal Study
•	Animals could be studied as surrogates for people
–	Important for medicine
–	But also for theories of learning and motivation
•	Some problems with making the boundaries fuzzy
–	Can animals think? – The problem of anthromorphism
–	What is unique about humans – he problems of human nature
Implications for Development
•	Haekel – ontogony recapitulates phylogony
–	Can’t study evolution directly
–	But can indirectly through development
•	Encouraged studies of human development
Adaptation and Functionalism
•	For evolution always ask what physical features are “good for”
•	Same analysis applied to psychological features
–	Instincts
–	Adaptive nature of sex and aggression
•	Important psychological features must be hard-wired
Individual Differences
•	Obviously if some are fitter than others individual differences are crucial
–	Intelligence
–	Strength
–	Attractiveness and other sexual features
•	The genetic basis of individual differences
Individual Differences and Francis Galton
•	Half cousin of Darwin
•	True genius
•	Interested in correlations among fathers and sons
–	Correlation -- Pearson was his student
–	Regression toward the mean
•	Also great hereditarian
–	Book on genius
–	Eugenics
Modern Evolutionary Psychology
•	Focus on sexual selection
•	Natural selection for mind
–	Responses to environment
–	But more importantly to social factors
•	Cooperation
•	Cheater detection