Evolution in Nature und Culture Prospects and problems of generalized evolution theory Gerhard Schurz (DCLPS, HHU Düsseldorf ) schurz@hhu.de ( Evolution in Natur und Kultur , Spektrum Akademischer Verlag, Heidelberg 2011. Englisch translation in progress)
1. From biological to cultural evolution The theory of biological evolution theory has frequently been misinterpreted: automatically leading to higher development survival of the strongest The generalized theory of cultural evolution is a comparatively young research program Richard Dawkins (1976): memes – as cultural counterparts of genes Culture ‚in the broad sense‘: reproduction of acquired (not genetically inherited) traits (different from to sociobiology) Co-founders of generalized theory of evolution: Charles S. Peirce, James M. Baldwin, Karl Popper, Donald T. Campbell, Daniel Dennett ... Cafalli-Sforza and Feldman (1973) Boyd and Richerson (1985) Susan Blackmore (1999): memetics (overstatements … ) Evolutionary game theory (Weibull, Skyrms, ...) Evolution in nature und culture Gerhard Schurz GENEVO Düsseldorf 2018 2
2. Three (abstract Darwinian) components of generalized evolution: 1. Reproduction: Evolutionary systems reproduce themselves in the form of successive generations. 2. Variation: Reproduction brings along variations that are themselves reproduced (inherited). (variation rate not too high) 3. Selection: The effective reproduction rate = fitness of different variants in the given environment is different. The absolute population frequency is upper-bounded because of limited ressources. Therefore the fitter variants replace the less fitter ones (i.e., there is selection). Stability condition for directed evolution: The selection 'forces' (conditions) don't change for many generations ─ or if they do, then in a regular and easily predictable way. The evolutionary tree of descendance: Diversity of variants arises mainly through specialization towards different ecological niches. "No diversity without partial separation" Under equal selection conditions evolution tends to eliminate diversity, except via special mechanisms: 'balanced polymorphism'. Evolution in nature und culture Gerhard Schurz GENEVO Düsseldorf 2018 3
Moreover, nonadaptive processes in evolution: Selectively neutral mutations → random drifts (without selection) E.g., In BE: neutral amino acids In CE: evolution of language Clarifications from the philosophy of science perspective: There are no evolutionary ‚forces‘ sui generis. Evolutionary ‚forces‘ supervene on ordinary physical forces. Empirial content of the theory of evolution: Is not contained in the most general laws of evolution. "Selection of the fittest" is a tautology (cf. Sober 1993) → Most general laws are mathematically valid (If… Then...) The empirical content is contained in the assertion that there ARE (or have been) these and those evolutionary systems and processes. The simultaneous implementation of all three modules of evolution is an extremely rare phenomenon in our universe. Cf. Ward/Brownlee 2000, Rare Earth . Evolution in nature und culture Gerhard Schurz GENEVO Düsseldorf 2018 4
Is cultural evolution more than a mere metaphor? Thesis: Yes General. Evol. Biological Evol. (BE) Cultural Evolution (CE) Evolutionary Organisms in their Human societies systems environment Reprones Genes in the cell Memes / acquired information nucleus software of our brains Phenetic Organs, abilties Skills, behavioral patters, traits language, ideas, technology Variations Mutation, Interpretation, guided vari- recombination ation of passed on memes Reproduction Replication, DNS-copy Imitation, social learning sexual reprod., diploid asexual, blending inheritance ─ Via higher reproduction rate of ─ Selection genes memes Evolution in nature und culture Gerhard Schurz GENEVO Düsseldorf 2018 5
Further generalizations of evolution theory: e.g. RNA chains Protoevolution: retention instead of reproduction (D.T. Campell). → Focus of this talk: CE. 3. Why should we transfer the theory of evolution to the development of cultures? 3.1) CE is neither reducible to BE … → mainly because of the speed of CE: genetic similarity between human and chimpanzee (further reasons, e.g. human creativity) … nor to the achievement of individuals (individual learning) → because CE transcends millionfold what individual geniuses can achieve 3.2) The non- intentionality of CE ─ it doesn't seem to follow global plans → Who wanted all that? The example of technological evolution (Basalla 1988): E.g. automobile 1900 vs. today; internet; mob. phone; … global warming. → simultaneous production of new technology & new demand. Evolution in nature und culture Gerhard Schurz GENEVO Düsseldorf 2018 6
There are many parallelisms between BE und CE, also between their subfields (e.g. genetics – neuroscience; cf. Mesoudi). Even more: Generalized theory of evolution = unification of biological population dynamics, memetics and evolutionary game theory Yet there is severe critique of memetics: Memes are not 'viruses of the mind' (++). Memetics is not a science of its own (+). CE is not applicable to humans and cultures (-). We have to ask: what are the differences between BE and CE? General Evol. Biological Evol. (BE) Cultural Evol (CE) D for " structural difference" Evolutionary Organisms in their Human societies systems environment Thus, CE takes place within BE Reprones Genes in the cell Memes / acquired information nucleus Software of our brains D: Identity Molecular & functional Only functional definition conditions definition problem of vagueness Evolution in nature und culture Gerhard Schurz GENEVO Düsseldorf 2018 7
BE: CE: Phenetic Organs, abilties Skills, behavioral patterns, traits language, ideas, technology clear ← distinction repron - phen → D: unclear (!) Variations Mutation, Interpretation, guided vari- Recombination ation of passed on memes D: mostly (S-) undirected goal-directed (but fallible) D: Macrovariations Macrovariations ('revolutions') difficult easier possible Reproduction Replication, DNA copy Imitation, social learning D: syntactic semantic D: sexual reprod., diploid asexual, blending inheritance D: Species: intrinsic Quasispecies: no intrinsic reproducion barriers reproduction barriers D: Tree of descendance Graph of descendence (only branching) (merging possible) ← next common ancestor → unique ambiguous 8 Evolution in nature und culture Gerhard Schurz GENEVO Düsseldorf 2018
BE: CE: ─ Via higher reproduction rate of ─ Selection genes memes Usually frequency Often frequency dependent D: independent Direction becomes easily stable direction instable D: Criteria of fitness: Criteria of fitness: heterogeneous Question of power: who determines depends on ecological niche the selection parameters? Meme dissemination, advertising D: Fertility fitness Barriers: Barriers: Offspring ends in Dictatorships: meme prohibitions food chain Information societies: Meme filters Dictatorship: coercion, indoctrination D: Survival fitness: Survive until reproduct. Democracies: Meme freedom Water, nutrition, temp. Meme 'survival' in argumentation: Protection against Connection with rationality ? predators Higher truth chances ? Evolution in nature und culture Gerhard Schurz GENEVO Düsseldorf 2018 9
6. Towards a unified theory of evolutionary systems 6.1 Frequency-independent selection − standard case of BE: General equation: X i = competing variants f(X k ) . fitness(X k ) f ( X i ) = frequency of X i Next(f(X k )) = Σ i f(X i ) . fitness(X i ) Next(f) = f in next generation Stability condition: Next(f(X k )) = f(X k ) Selection of advantageous & dominant allele A with backward mutation Genotypes: AA Aa aa 2f(1 − f) (1 − f) 2 where f(A) = f, f(a) = 1 − f f 2 Frequencies: 1 − s Relative Fitness: 1 1 s = selection disadvantage Effective mutation rate: m: A → a Calculation gives: Next(f)) = f . (1 − m) . Stability condition, Next(f*) =! f*, implies f* = 1 − 10 Evolution in nature und culture Gerhard Schurz GENEVO Düsseldorf 2018
→ Result: directed evolution (stable equilibrium) almost-fixation of A Frequency 1 f*(A) = 1 − m s Evolution condition: m < s m f*(a) = s Generations 0 6.2 Analogous in CE, but without diploidy; thus even simpler: Selection of advantageous meme with backward 'mutation' m: A → B Memes: A B Calculation gives: 1 − f Next(f)) = f . (1 − m) . Frequencies: f 1 − s Relative Fitness: 1 Stability condition implies: f* = 1 − (m/s) Mutation rate: m: A → a Evolution in nature und culture Gerhard Schurz GENEVO Düsseldorf 2018 11
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