Cultural Evolution

Cultural Evolution

1. EXAMPLES

   • Humans: has allowed foragers to occupy a wider ecological range than any other species.
   • Dolphins: using puffer fishes to get high. Wear sponges to look nice or fish.
   • Chimpanzees: evidence of cultural transmission and social learning.
     • BUT: no evidence of CUMULATIVE cultural transmission. Technology remains simple
       • Whitnen et.al. 1999
         • Whitnen + Schaik 2007: CULTURE PYRAMID.
           • Foundation layer: social learning. In most vertebrates and some invertebrates.
           • Layer 2: traditions. Only in some whereby social learning is not transitory
           • Layer 3: culture. Multiple traditions existing in the same species forming unique local complexes.
           • Layer 4: CUMULATIVE culture. Only in humans, whereby more complex traditions arise on elaboration of earlier ones
     • = Idea transmitted from one indivdiual to another

2. MEMES

   • Dawkins 1976
   • “An element of a culture or system of behaviour that may be considered to be passed from one individual to another by non-genetic means, especially imitation.”
     • e.g. “tunes, ideas, catch-phrases, clothes fashions, ways of making pots or building arches”
   • As replicators
     • must have evolutionary interests
     • neither nature or nurture - a third way: inherited ideas from others
     • CO-EVOLUTION between genes and culture (a cultural trait may affect the evolution of a genetic trait)

3. CUMULATIVE CULTURAL TRANSMISSION

   • = building on earlier culturally transmitted ideas and adding to it
     • Neccessary for language, art, technology, complex social institutions
       • Sophisticated tools, art etc. emerged in upper Paleolithic - well AFTER modern humans emerged.
   • Powell et.al. (2009): POPULATION DENSITY (not just cognitive ability)
     • produces enough contact/migratory contact for complex culture to evolve
     • Henrich (2004): low population density/ low migratory rates --> inability to learn complex cultural traits.
       • e.g. HOLOCENE TASMANIANS. separation from mainland (that had cultural complexity) and decrease in pop size, technology and valuable skills were lost of 8,000 year-period. Probably due to lack of 'cultural parents'.
       • Derex et.al. (2013): LAB EXPERIMENT. demonstrated group size maintains and IMPROVES skills in complex tool-making tasks.
   • POLITICAL COMPLEXITY
     • Is there a regular evolutionary sequence from simple to complex political organisation in human societies?
     • Emergence in the PACIFIC
       • Studied with the 'AUSTRONESIAN LANGUAGE family' tree
         • used 84 LANGUAGES from Austronesian Basic Vocabulary database - and a sample of 1000 trees
         • languages matched to 84 SOCIETIES in Ethnographic Atlas
         • Used statistical approaches looking for different EVOLUTIONARY PATTERNS. 6 models used.
           • Models of sequential and non-sequential political evolution
             • A = Acephalous (no leader)
             • sC = Simple Cheifdom
             • cC = Complex Chiefdom
             • S = State
             • STATISTICAL SUPPORT: Sequential methods had highest BAYES FACTOR (stat method of model selection)
               • Societies get more/less complex in a step-wise manner, not all in one go. (decrease in complexity could do this however - a 'collapse in complexity' - relaxed unilinear)
         • Currie et.al. 2010
   • DUAL INHERITANCE MODEL
     • Human behaviour is a product of two evolutionary processes: genetic evolution and cultural evolution
     • Culture can be developed within a gene pool de novo, but is also inherited from one gene pool to the next. There is also interaction with natural selection whereby genes and culture co-evolve
     • Co-evolution examples
       • Lactose-tolerance in Europe and Africa as adaptation to dairying
       • Genes against prion brain disease in NewGuinea cannibals
       • Alcohol dehydrognease in east Asia as adaptation to rice domestication
     • NICHE CONSTRUCTION
       • Dawkins 1982: "extended phenotype". Beavers.
       • 3 consequences
         • counteract NS
         • create novel selection pressures
         • another form of inheritance: ecological inheritance (e.g. nest) -> in turn influences genes
       • Applications in hominid evolution
         • LINEAGE DIVERGENCE
           • 1. diff ext environment -> diff selection pressures
           • 2. same selection pressure -> one pop niche constructs
           • 3. both NS but in different ways
           • 4. early NS of one pop due to mutation/discovery -> cause environment to change
           • 5. Different kinds of early NS
         • RAPID EVOLUTION
           • cult transmission homogenises population behaviour + cult traits spread rapidly (via language + non-randomness) -> STRONG SELECTION
             • resistant to genetic evolution in response to changing environments?
             • BUT: decelerates selection too - counteractive genetic NS
               • e.g. improved health care allows the spread of genetic diseases
     • Genes will catch up
       • Culture homoginises individuals -> decrease in cultural variant variation -> decrease in cultural evolution rate -> lagging changes in genetic variants increase in importance -> cultural system reaches equilibrium -> gene selection determines shift

4. NATURAL vs. CULTURAL SELECTION

   • -Does culture evolve in a Darwinian way? -Does cultural evolution allow us to do unique things? -Why do humans do maladaptive things?
     • Perhaps anything to do with cultural evolution is proximate? Hence why some behaviour is evo maladaptive
     • Does cultural selection generate behaviour that cannot be explained in a Darwinian framework?
   • BIASED CULTURAL TRANSMISSION
     • Boyd + Richerson 1985: who we choose to copy matters
     • = preferentially copying from certain cultural parents
       • DIRECT bias = those with highest returns (i.e.most successful)
       • PRESTIGE bias = most respected in society
         • MALADAPTIVE BEHAVIOUR
           • Cultural variants that aid in attaining influence spread
             • Variants can be maladaptive. E.g. famous sportsman takes great risk to health.
         • PRESTIGE MODEL
           • People will copy prestigious individuals, even outside their range of expertise
           • Skilled individuals have higher prestige
           • Prestigious people are memorable
           • Prestige associated with different psychology, rather than dominance
       • CONFORMIST bias = those doing most common strategy
     • 'Costly information hypothesis'
       • = trade-off between acquiring accurate info at high cost, or less accurate at a lower cost -> NS should select strategies enabling one to extract significant info from others at low cost
       • CONTENT BIAS
         • acquiring info because seems more appealing
           • e.g. learning behaviour that involves resources easily obtainable to you
       • CONTEXT BIAS
         • acquiring info from models
           • depends WHO holds ideas and how COMMON they are
       • Models: Success + Prestige biases
         • Boyd + Richerson
         • direct, prestige, conformist bias
         • CUES: imitate those who share same ethnic markers -> more likely to fit with own abilities
           • kin + trust?
         • identifying who to imitate less costly than trial-and-error learning
           • GULLIBILITY: believe what previous gen demonstrates because verifying all info too costly
       • Conformist Transmission
         • allows individuals to aggregate behavioural info of multiple individuals containing effects of own experiences and learning efforts
           • good route to adaptation in info-poor environments
         • + Cooperation
           • cost of alt punishment independent of defector frequency in large pop -> cost of alt punishment decreases as defectors become rare -> alt punishment common -> conformist transmission stabilises punishment -> stabilises cooperation
             • stabilised in one group -> cultural group selection -> punishment spread through multi-group pop
               • prosocial genes decrease one's risk of punishment -> coop genes spread
           • Guzman et.al.
   • CULTURAL GROUP SELECTION
     • = heritable variation between groups + intergroup conflict
       • genes enabling out competing other groups spread
     • MEMES? Not inherited in same way as genes - perhaps group/multi-level selection possible in cultural evolution?
     • LINGUISTIC DIVERSITY + SPECIES DIVERSITY
       • Language boundaries divide populations culturally, even when genetic distinctions are blurred
         • Original ethnoliguistic groups could have begun with as little as 600 individuals
       • LINK: same forces causing extinction/diversity cause cultures/languages to die out/diversify
         • connection between geographical barriers and language barriers (migration prevented)
       • LANGUAGE TREES
         • language similarity -> phylogenies of culture
         • Why are language trees easier to determine than genetic trees?
           • 1. migration -> adopting THEIR language + cultural traits -> offspring will inherit
             • Genes will be contributed to the gene pool - own cultural traits will not
           • 2. human cultures do not share a habitat (even with diverse and abundant resources) due to intergroup conflict/violence
             • e.g. Amazon Rainforest
     • allows evolution of complex group structure
     • WARFARE -> GROUP COHESION
       • intergroup conflict. e.g. Yanamamo villages with barracades
       • MIGRATION: Altruistic group more successful in warfare -> Non-alruistic outsider from other group joins -> their reproductive success increases -> spread in A- -> selection against A+?
         • BUT: CONFORMIST BIAS -> immigrants take the form of the majority
           • ONLY IF: high rates of group formation + extinction
           • Boyd + Richerson
         • individual selection FASTER than group selection
     • PUNISHMENT -> GROUP COOPERATION
       • POLICING + RELIGION -> stable large-scale cooperation between unrelated
       • Fehr + Gachter 2003: anonymous public goods game -> cooperation collapses without punishment
         • free-riding
           • controlled in small populations with low migration
           • punishment enables control in larger populations (interdroup migration must still be low)
             • Boyd et.al 2003
               • altruistic punishment ESS in groups of 600
             • Guzman et.al. 2007: CONFORMISM added to model -> also stabilises cooperation in large groups
               • larger groups
             • reason for xenophobia?
       • HUMAN DISTINCTIONS

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