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Mesoudi et al


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Mesoudi et al

  1. 1. Towards a unified science of cultural evolution The study of culture can and should be viewed within an evolutionary framework, which will allow for the application of more rigorous scientific methodologies in the social sciences and stimulate progress in the science of culture.
  2. 2. Culture & cultural evolution <ul><li>Culture - ‘information capable of affecting individuals’ behaviour that they acquire from other members of their species through teaching, imitation and other forms of social transmissions.’ </li></ul><ul><li>Cultural evolution - ‘a Darwinian process comprising the selective retention of favourable culturally transmitted variants, as well as a variety of non-selective processes.’ </li></ul><ul><ul><li>Mesoudi et al (2004) present case for culture exhibiting Darwinian properties </li></ul></ul>
  3. 3. ‘ Darwinian’? <ul><li>The authors claim that culture exhibits ‘key Darwinian evolutionary properties’ -- but this is ambiguous. </li></ul><ul><li>1. A general theory of biological evolution . </li></ul><ul><li>2. A theory of biological inheritance in which Weissman’s barrier separates the replicator and interactor (in contrast to Lamarckian inheritance). </li></ul>
  4. 4. Oh, the social sciences… <ul><li>Cultural and social anthropology, disciplines devoted to the study of culture, have been relatively unproductive (as far as developing theories and amassing a reliable body of data). </li></ul><ul><ul><li>Often view cultures as unique and not subject to general principles </li></ul></ul><ul><ul><li>Hostile to the idea of Darwinian cultural evolution (usually from misunderstandings of term-- biological determinism, etc…) </li></ul></ul><ul><ul><li>reject any ‘scientific’ approach to culture , distaste for ‘facts’ and ‘evidence’ </li></ul></ul><ul><li>Evolutionary biology has made substantial progress since its development. Its success can be attributed to a number of factors: </li></ul><ul><ul><li>Willing to make simplifying assumptions and use somewhat crude methods for the purposes of making the investigation of immensely complex systems more manageable </li></ul></ul><ul><ul><li>Accumulation of knowledge using such techniques ultimately leads to a more sophisticated understanding </li></ul></ul><ul><ul><li>The ‘evolutionary synthesis’ has led to diverse subfields of biology contributing to and spurring progress in each other </li></ul></ul>
  5. 5. Why an evolutionary framework? <ul><li>Although human culture is enormously complex, the use of simplifying assumptions and models has greatly benefited the arguably equally complex study of biological systems. </li></ul><ul><li>An ‘evolutionary synthesis’ for the science of culture can highlight the fact that traditionally disparate fields are investigating complementary aspects of the same problem. </li></ul><ul><li>Makes available a set of methods developed within evolutionary biology that are applicable to the study of culture (with the necessary adaptations). </li></ul><ul><li>Similarity in the underlying processes of both cultural evolution and evolutionary biology </li></ul><ul><li>Mesoudi et al 2004 found that, along with the three features of discussed above, cultural traits exhibit other characteristics of biological evolution: </li></ul><ul><ul><li>extinction of traits due to competition </li></ul></ul><ul><ul><li>accumulation of modifications </li></ul></ul><ul><ul><li>adaptation to the environment </li></ul></ul><ul><ul><li>geographical distribution of variation </li></ul></ul><ul><ul><li>convergent evolution of similar forms </li></ul></ul><ul><ul><li>change in function/become vestigial </li></ul></ul><ul><li>The authors stress that the biological and cultural processes are not identical, and the differences should be considered when methods and models are applied to cultural evolution. They also point out that criticism often involves appealing to a range of differences; however, they claim that many of these purported differences can be shown to be unfounded. </li></ul>
  6. 6. We know what you’re thinking <ul><li>Intentionality of cultural evolution vs. ‘blind’ biological evolution </li></ul><ul><ul><li>BUT there is evidence for both directed and undirected variation, and studies have shown that the most successful innovations are the result of trial & error. </li></ul></ul><ul><li>Cultural traits do not form a homogenous set, and the dynamics of evolutionary processes may vary widely between different forms. </li></ul><ul><ul><li>BUT this doesn’t mean that different processes can’t be modeled accordingly, and biology deals with similar issues. </li></ul></ul><ul><li>‘ Social constructions’ are particularly thorny and have no biological equivalent. </li></ul><ul><ul><li>BUT this only means that techniques from biology can’t be applied without modification. It is still possible to view these phenomena in a general evolutionary framework. </li></ul></ul>
  7. 7. Parallels to evolutionary biology (Please see page 331)
  8. 8. Systematics <ul><li>Biology </li></ul><ul><li>the study of the diversity of organisms and the relationships between them </li></ul><ul><li>use cladistics - based on phylogeny </li></ul><ul><li>identify shared derived traits in order to determine if a feature is homologous or analogous; once SDTs are known, can be used to place branches on a phylogentic tree </li></ul><ul><li>employ statistical packages/computer programs to construct trees (PAUP) </li></ul><ul><li>Culture </li></ul><ul><li>anthropologists attempt to reconstruct the history of groups of people based on cultural traits </li></ul><ul><li>face similar problem of distinguishing between homologues & analogues (‘Galton’s problem’) </li></ul><ul><li>previously used methods have produced unsatisfactory results </li></ul><ul><li>one option: treat cultural traits like biological characters, apply same statistical methods (Bantu languages) </li></ul><ul><li>BUT… </li></ul><ul><li>issue of identifying cultural ‘characters’ </li></ul><ul><li>issue of horizontal transmission </li></ul><ul><ul><li>‘ cross-lineage’ transfer also occurs in biology </li></ul></ul><ul><ul><li>cultural data sets show good fit with phylogenetic models </li></ul></ul><ul><ul><li>additional techniques can be developed to incorporate horizontal transmission </li></ul></ul>
  9. 9. Paleobiology <ul><li>Biology </li></ul><ul><li>study of how biological, ecological, geographical & historical factors determine the spatial distribution of organisms </li></ul><ul><li>fossil record and phylogenetic analyses are used to discover the past distribution of organisms </li></ul><ul><li>descriptive methods document range of data for a particular organism, then analytical methods used to construct models </li></ul><ul><li>Culture </li></ul><ul><li>archaeologists reconstruct lineages of prehistoric artifacts and people associated with them </li></ul><ul><li>share the assumption that similar forms that vary through time are causally connected by inheritance </li></ul><ul><li>traditionally taken ‘essentialist stance’ </li></ul><ul><li>seriation better suited to constructing evolutionary lineages </li></ul><ul><ul><li>still must distinguish between homologous and analogous traits </li></ul></ul><ul><ul><li>adoption of phylogenetic methods allows for accurate reconstruction </li></ul></ul><ul><li>neutral drift models also adapted from EB </li></ul>
  10. 10. Biogeography <ul><li>Biology </li></ul><ul><li>study of how biological, ecological, geographical & historical factors determine the spatial distribution of organisms </li></ul><ul><li>fossil record and phylogenetic analyses are used to discover the past distribution of organisms </li></ul><ul><li>descriptive methods document range of data for a particular organism, then analytical methods used to construct models </li></ul><ul><li>Culture </li></ul><ul><li>one goal of anthropology is to document the worldwide distribution of cultural traits (similar to descriptive method used in biogeography) </li></ul><ul><li>geographical distribution of cultural traits is shaped by similar factors as organisms </li></ul><ul><li>recently, analytical models have been developed to account for distributions </li></ul><ul><ul><li>cladistic methods used to explain present distribution </li></ul></ul><ul><ul><li>used to distinguish between ecologically-based and inherited traits </li></ul></ul><ul><li>Utilization of models should allow the field to become more predictive - develop hypotheses about how certain traits are transmitted and under what conditions </li></ul>
  11. 11. Theoretical population genetics <ul><li>Biology </li></ul><ul><li>The development of mathematical models contributed greatly to the study of biological evolution before the underlying processes were fully understood </li></ul><ul><li>Mutation, non-random mating and impact of natural selection and drift can be built into models and genotype frequencies are tracked </li></ul><ul><li>Determine dynamics of particular genetic traits within a population </li></ul><ul><li>Culture </li></ul><ul><li>SS often hostile towards use of mathematical models because it is seen as oversimplifying reality, but alternative approaches yield unsatisfactory results </li></ul><ul><li>Models benefit from parallels between the demographic consequences of biological and cultural change </li></ul><ul><ul><li>Differential adoption and innovation of cultural traits is equivalent to natural selection and mutation </li></ul></ul><ul><ul><li>drift, migration and non-random mating also operate equivalently </li></ul></ul><ul><ul><li>highlight broad, robust patterns </li></ul></ul><ul><li>Gene-culture coevolution studies have adopted similar methods by assimilating cultural inheritance into population genetic models </li></ul><ul><ul><li>horizontal & ‘oblique’ transmission </li></ul></ul><ul><ul><li>‘ conformist’ bias </li></ul></ul>
  12. 12. Experimental population genetics <ul><li>Biology </li></ul><ul><li>Study of microevolutionary processes by breeding multiple generations of organisms in the laboratory to simulate evolution under controlled conditions </li></ul><ul><li>Experiments have been used to understand a number of evolutionary processes: </li></ul><ul><ul><li>estimations of rate and effect of mutation </li></ul></ul><ul><ul><li>detect adaptations to manipulated environmental conditions (natural selection) </li></ul></ul><ul><ul><li>responses to artificial selection </li></ul></ul><ul><li>Culture </li></ul><ul><li>Obvious parallel in psychological experiments simulating cultural transmission through social learning </li></ul><ul><li>Experimental economics has studied the emergence of behavioural traditions in economic games </li></ul><ul><li>Transmission chain method - some artifact is passed along a chain of participants </li></ul><ul><ul><li>observing how material changes during transmission and comparing how this differs between different types of materials can show biases in cultural transmission </li></ul></ul><ul><ul><li>cultural information is shaped by the minds of the participants that it passes through (sound familiar?) </li></ul></ul><ul><ul><li>resemble paradigms in population genetics less, but offer important information on the mode of cultural transmission, which is necessary for the development of more advanced experimental conditions </li></ul></ul>
  13. 13. Population genetics: Field studies <ul><li>Biology </li></ul><ul><li>Study of evolution in naturally occurring populations </li></ul><ul><li>Can give estimates of heritability of traits through measurement of parent-offspring correlations </li></ul><ul><li>Mode and strength of selection can be estimated using measures of mortality and reproductive success </li></ul><ul><ul><li>a selection gradient , which measures the relationship between relative fitness and variation, represents strength of selection </li></ul></ul><ul><li>Endler’s 10 methods for detecting natural selection in the wild </li></ul><ul><li>Culture </li></ul><ul><li>Traditional paradigms include anthropological field studies, rumour research and diffusion of innovations </li></ul><ul><ul><li>An issue for these techniques is that they do not identify selection pressures before undertaking a study, and thus cannot test a prediction in a natural population </li></ul></ul><ul><li>Cultural evolution may be easier to detect because it operates on a much shorter timescale and means of transmission can be determined </li></ul><ul><li>Even so, cultural studies do not have formal tests for selection </li></ul><ul><li>Convergent evolution might be detected where lineages from different areas share similar environmental features </li></ul><ul><li>Quantitative measures of microevolution could be used to develop a selection gradient </li></ul>
  14. 14. Evolutionary ecology <ul><li>Biology </li></ul><ul><li>Focuses on the evolutionary processes by which organisms have become adapted to their environments </li></ul><ul><ul><li>abiotic and biotic features </li></ul></ul><ul><li>Methods include field studies, natural and laboratory experiments and mathematical models </li></ul><ul><li>Overlaps considerably with biogeography and population genetics </li></ul><ul><li>Culture </li></ul><ul><li>Cultural traits can be seen as interacting with and adapting to their environment, which can be divided into 3 categories: </li></ul><ul><ul><li>physical features (akin to abiotic) </li></ul></ul><ul><ul><li>other cultural knowledge (biotic) </li></ul></ul><ul><ul><li>biologically evolved or implicit features of human cognition </li></ul></ul><ul><li>HBE uses Darwinian methods to determine how cultural traits adapt to their physical and social environment (formal mathematical models) </li></ul><ul><li>Pre-existing cultural knowledge affects how a trait will evolve and involves competition between traits </li></ul><ul><li>Traits rely (for the most part) on human minds for storage and transmission </li></ul><ul><ul><li>Evolutionary psychology research may help predict sources of bias in transmission </li></ul></ul><ul><li>Adaptation to alternative and novel media </li></ul>
  15. 15. Molecular genetics <ul><li>Biology </li></ul><ul><li>Study of the structure of DNA, RNA and proteins and the processes involved in inheritance and expression </li></ul><ul><li>In evolutionary biology, used to reconstruct phylogenetic relationships </li></ul><ul><li>Also used to study genetic variation, population structure and gene flow </li></ul><ul><li>Culture </li></ul><ul><li>Memetics (* shudder *) - the study of cultural replicators, memes . </li></ul><ul><ul><li>widely criticised - culture cannot be cleanly divided into discrete units </li></ul></ul><ul><li>However, the modern concept of genes could be criticised for similar reasons ( overlapping , movable and nested genes), yet it has still resulted in considerable progress in evolutionary biology </li></ul><ul><li>Mechanisms of cultural transmission still require a more detailed understanding of how the brain processes relevant information. This can be approached from multiple levels: </li></ul><ul><ul><li>neural (limited by lack of understanding of neural processes in learning & memory) </li></ul></ul><ul><ul><li>whole brain (fMRI studies of imitation) </li></ul></ul><ul><ul><li>cognitive (social learning in great apes and humans) </li></ul></ul>
  16. 16. Molecular genetics (cont.) <ul><li>Biology </li></ul><ul><li>Study of the structure of DNA, RNA and proteins and the processes involved in inheritance and expression </li></ul><ul><li>In evolutionary biology, used to reconstruct phylogenetic relationships </li></ul><ul><li>Also used to study genetic variation, population structure and gene flow </li></ul><ul><li>Culture </li></ul><ul><li>Despite the inherent problems associated with the quantification of cultural traits, treating them as discrete units makes it possible to observe patterns in the processes involved in cultural evolution (it’s worked for genes…?) </li></ul><ul><li>There may be no cultural equivalent to molecular biology, BUT useful models can still be developed that address cultural transmission at the behavioural or cognitive level </li></ul><ul><li>What about the genotype-phenotype distinction? </li></ul><ul><ul><li>semantic info in brains = replicators </li></ul></ul><ul><ul><li>expression in behaviour or artifacts = interactors </li></ul></ul><ul><ul><li>does it really matter? </li></ul></ul><ul><li>Methods can still be applied or adapted despite a limited understanding of the underlying processes </li></ul>
  17. 17. Can these methods be used to study nonhuman culture? <ul><li>There is evidence of socially learned cultural patterns in other species. </li></ul><ul><ul><li>Regional differences in behaviour have been documented for chimpanzees, orangutans, capuchins, some species of birds and cetaceans. </li></ul></ul><ul><li>Diffusion of innovations in nonhuman communities has been observed. </li></ul><ul><ul><li>Some cases of diffusion in primates show the same S-shaped distribution found in human communities. </li></ul></ul><ul><li>Population genetics models have been employed to analyse patterns of birdsong. Gene-culture coevolution models have also been used. </li></ul><ul><li>The transmission chain method has been used to study social learning in a number of species . </li></ul>
  18. 18. Conclusions <ul><li>There are a myriad of opportunities for the social sciences to adopt techniques from evolutionary biology </li></ul><ul><li>Evolutionary methods have produced significant advances over traditional methods </li></ul><ul><li>Adopting an evolutionary framework does not mean imitating evolutionary biology. Adaptations of methods will be necessary, as well as the development of novel ones. </li></ul><ul><li>The integration and coordination of disparate subfields within the social sciences will spur progress and highlight shared concerns. </li></ul>
  19. 19. Peer Commentary <ul><li>Extensions </li></ul><ul><ul><li>Organisational ecology, evolutionary game theory, agent-based modeling </li></ul></ul><ul><ul><li>Signaling theory, evolutionary developmental biology, niche-construction </li></ul></ul><ul><ul><li>Ethnographic methods, Vertical integration </li></ul></ul><ul><li>Disputes </li></ul><ul><ul><li>Culture as semantic information </li></ul></ul><ul><ul><ul><li>The significant role of artifacts in cultural transmission </li></ul></ul></ul><ul><ul><ul><li>(Susan Blackmore is out of her mind) </li></ul></ul></ul><ul><ul><li>Cultural traits </li></ul></ul><ul><ul><ul><li>Weaknesses in the identification and use of ‘cultural traits’; may be unproductive to treat them all similarly </li></ul></ul></ul><ul><ul><ul><li>Can be viewed as ‘recipes’ - interrelated conceptual structures </li></ul></ul></ul><ul><ul><li>Cultural inheritance </li></ul></ul><ul><ul><ul><li>Different forms of transmission; distinction between Lamarckian and ‘Weissmanian’ </li></ul></ul></ul><ul><ul><li>Cultural selection </li></ul></ul><ul><ul><ul><li>No explicit definition of selection processes </li></ul></ul></ul><ul><ul><ul><li>Darwinian evolution cannot deal with selection at the social level (operates on individuals) </li></ul></ul></ul><ul><ul><ul><li>Macroevolution is not simply Darwinian microevolution on a large scale </li></ul></ul></ul>
  20. 20. Peer Commentary (cont.) <ul><li>Disputes (cont.) </li></ul><ul><ul><li>Mechanisms of cultural transmission </li></ul></ul><ul><ul><ul><li>Cultural transmission is currently poorly understood </li></ul></ul></ul><ul><ul><ul><li>Cultural phenomena may be accounted for by biological processes (evoked responses) </li></ul></ul></ul><ul><ul><li>Role of intentionality </li></ul></ul><ul><ul><li>Relationship between biological and cultural evolution </li></ul></ul><ul><ul><ul><li>Culture is not always biologically adaptive </li></ul></ul></ul>