Cultural Evolution Theory

April 6, 2000

*Indicates a paper with less mathematical notation and more prose relative to other papers

Everyone Read This Paper
*Laland, K. N., P. J. Richerson, and R. Boyd. 1996. Developing a Theory of Animal Social Learning. Pages 129-154 in C. M. Heyes and B. G. Galef, eds. Social learning in animals the roots of culture. Academic Press, San Diego.

Cultural Evolution
*Boyd, R. and P. J. Richerson. 1985. Ch 9: Conclusion. Pages 280-299 in R. Boyd and P. J. Richerson, eds. Culture and the evolutionary process. University of Chicago Press, Chicago.

*Boyd, R. and P. J. Richerson. 1988. An Evolutionary Model of Social Learning: The Effects of Spatial and Temporal Variation. Pages 29-48 in T. R. Zentall and B. G. Galef, eds. Social learning psychological and biological perspectives. Lawrence Erlbaum Associates, Hillsdale, NJ.

Cavalli-Sforza, L. L. and M. W. Feldman. 1983. Paradox of the evolution of communication and of social interactivity. Proc Natl Acad Sci U S A 80:2017-21.
Abstract: Communication between individuals of a species is likely to increase the capacity to acquire skills useful for survival and propagation and thus may confer important selective advantages. Since interaction occurs between two or more individuals, the selective process is frequency dependent, and the analysis shows that communication cannot initially increase at a reasonable rate when it is limited to random unrelated individuals, so that it is likely to abort for stochastic reasons. However, this bottleneck is removed if the communication process takes place in the nuclear family or among close relatives or if aggregation of communicators occurs because of assortative mating or meeting. Use of the individual conditional fitnesses we have introduced earlier permits an exact analysis. We show that, in general, the initial rate of increase can be geometric if and only if, in the class of selective models considered, the conditional probability of a communicator interacting with another contains a positive constant term. In our discussion of communication, cost factors for the act of communication have been omitted. However, the model has been generalized to include cooperativeness, and also altruism, or competition, by introducing costs. There is a close relationship among these situations, and the same considerations about the initial bottleneck and its resolution also extend to them. The models given here are for haploids but they extend to diploids and the conclusions are similar.

Findlay, C. S., C. J. Lumsden, and R. I. Hansell. 1989. Behavioral evolution and biocultural games: vertical cultural transmission. Proc Natl Acad Sci U S A 86:568-72.
Abstract: We consider an evolutionary game model in which strategies are transmitted culturally from parents to offspring rather than inherited biologically. Our analysis yields two noteworthy results. First, biocultural games show a greater diversity of dynamical behaviors than their purely biological counterparts, including multiple fully polymorphic equilibria. Second, biocultural games on average exhibit greater equilibrium strategy diversity because of the countervailing influences of cultural transmission and natural selection. Therefore, knowledge of a strategy's influence on Darwinian fitness is not sufficient to infer the evolutionary consequences of biocultural games. Further, our results suggest that cultural transmission in the presence of natural selection may be an important mechanism maintaining behavioral diversity in natural populations.

*Pocklington, R. and Best, M. L. Cultural Evolution and Units of Selection in Replicating Text. Journal of Theoretical Biology. 1997 Sep 7; 188(1):79-87.
Abstract: The use of biological models and metaphors in studies of culture has a long and checkered history. While there are many superficial similarities between biological and cultural evolution, attempts to pin down such analogies have not been wholly successful. One limiting factor may be a lack of empirical evidence that the basic assumptions of the evolutionary model are met within a cultural system. We argue that a focus on the detection and description of the units of selection is an essential first step in constructing any evolutionary model. In this paper we outline the necessary connection between units of selection and evolution, describe the properties of a unit of selection, and introduce an empirical method for the detection of putative units of selection in a model cultural system: discourse within NetNews, a discussion system on the Internet. (C) 1997 Academic Press Limited.

*Gatherer, D. and McEwan, N. R. On Units of Selection in Cultural Evolution. J Theor Biol. 1998 Jun 7; 192(3):409-413.


Takahasi, K. 1998. Evolution of transmission bias in cultural inheritance. J Theor Biol 190:147-59.
Abstract: Evolution of transmission bias in cultural inheritance is investigated using simple models of cultural selection. Conventional models of cultural transmission describe cultural changes by incorporating transmission bias and non-vertical pathways into the ordinary population genetic framework. The methodology has been successful in understanding cultural changes in terms of natural selection, but it is difficult to see from the theoretical framework how biased transmission in favor of maladaptive traits might have evolved. To show that ordinary cultural processes lead at times to the evolution of a preference that favors a deleterious cultural variant, this study presents an alternative model of cultural transmission, where cultural elements are transmitted in a manner more like infections in epidemiological transmission. An ordinary equilibrium analysis indicates that, under certain conditions, runaway dynamics emerges and the coevolution of a maladaptive cultural variant and an associated preference in favor of the maladaptive variant is observed. If the preference of an individual does not change during its ontogeny (e.g., if it is transmitted genetically), however, then cultural selection alone does not produce such runaway dynamics, and only those preferences that favor adaptive variants should eventually evolve. Since cultural processes may at times result in a reduction in the fitness of individuals, simplistic adaptive interpretations of culture are unconvincing without detailed specification of the cultural processes involved. Moreover, cultural runaway of this kind may help to explain the existence of traits that are apparently maladaptive at the individual level but may be advantageous for the group. Inferences are also made regarding the observed differences between human and non- human social information transfer.


Takahasi, K. 1999. Theoretical aspects of the mode of transmission in cultural inheritance. Theor Popul Biol 55:208-25.
Abstract: This study investigates how evolutionary factors interact to determine the relative importance of vertical versus nonvertical mode of transmission in cultural inheritance. Simple mathematical models are provided to study the joint evolution of two cultural characters, one determining the viability and the fertility of individuals, and the other determining the vertical transmission rate of the first trait. Ordinary local stability analyses indicate that intrademic processes should lead to a greater reliance on vertical cultural transmission. On the other hand, when newly arisen variants are adaptive and favored in biased cultural transmission, interdemic processes may lead to a decrease in vertical transmission. This is because biased nonvertical transmission may effectively propagate the adaptive variants, further increasing the average growth rate of the population. These results are verified under several distinct sets of assumptions. It is also inferred that the degree and intensity of transmission bias may be the important determinants of cultural processes. Copyright 1999 Academic Press.

Wallace, R. and Wallace, R. G. Organisms, Organizations and Interactions: an Information Theory Approach to Biocultural Evolution. Biosystems. 1999 Aug; 51(2):101-119.
Abstract: The language metaphor of theoretical biology, proposed by Waddington in 1972, provides a basis for the formal examination of how different self-reproducing structures interact in an extended evolutionary context. Such interactions have become central objects of study in fields ranging from human evolution-genes and culture-to economics-firms, markets and technology. Here we use the Shannon-McMillan Theorem, one of the fundamental asymptotic relations of probability theory, to study the 'weakest' and hence most universal, forms of interaction between generalized languages. We propose that the co-evolving gene-culture structure that permits human ultra- sociality emerged in a singular coagulation of genetic and cultural 'languages', in the general sense of the word. Human populations have since hosted series of culture-only speciations and coagulations, events that, in this formulation, do not become mired in the 'meme' concept. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.

Gene-Culture Coevolution
Aoki, K. and Feldman, M. W. Toward a theory for the evolution of cultural communication: coevolution of signal transmission and reception. Proc Natl Acad Sci U S A. 1987 Oct; 84(20):7164-8.
Abstract: A haploid sexual two-locus model of gene-culture coevolution is examined, in which a dichotomous phenotype subject to natural selection is transmitted vertically with probabilities dependent on the chosen parent's genotype and phenotype and the offspring's genotype. Stability conditions for the genetically monomorphic corner equilibria are obtained. In a specialization of this general model, one locus controls the transmission and the other controls the reception of adaptive information. The corner and edge equilibria of this doubly coevolutionary model are fully analyzed, and conditions for transmission and reception to coevolve are derived in terms of the efficiency of vertical transmission, the selective advantage gained from possessing the information, the costs of transmission and reception, and the recombination fraction between the two loci. Possible applications of the model are to the evolution of semantic alarm calls in vervet monkeys and the phonetic aspects of human language. In a third model with diploid genetics, we consider the initial increase of cultural transmission from a mutation-selection balance in which the adaptive phenotype is the consequence of a dominant gene at one locus. A second gene controls the transmission of the phenotype in such a way that a new mutant at this second locus permits learning of the adaptive phenotype from a parent who has it. This new mutant cannot increase when rare.

Aoki, K. and Feldman, M. W. A gene-culture coevolutionary model for brother-sister mating. Proc Natl Acad Sci U S A. 1997 Nov 25; 94(24):13046-50.
Abstract: We present a gene-culture coevolutionary model for brother-sister mating in the human. It is shown that cultural--as opposed to innate-- determination of mate preference may evolve, provided the inbreeding depression is sufficiently high. At this coevolutionary equilibrium, sib mating is avoided because of cultural pressures.

*Avital, E. and Jablonka, E. Social-Learning and the Evolution of Behavior. Animal Behaviour. 1994 Nov; 48(5):1195-1199.
Abstract: In animals capable of learning from a parent or other individual, socially acquired behaviour can be transmitted through several generations. When the inheritance of variations in such behaviour is independent of genotypic variations, natural selection can operate on an additional level. Direct evolution of behaviour becomes possible, and this may alter the estimates of costs and benefits of behaviour patterns for the individual who transmits them. It is suggested that the effects of maternally transmitted behaviour contribute to the evolution of maternal behavioural strategies, and to the evolution of behaviour associated with male-female conflict.


*Feldman, M. W. and Laland, K. N. Gene-culture coevolutionary theory. Trends in Ecology & Evolution. 1996 Nov; 11(11):453-457.
Abstract: Gene-culture coevolutionary theory is a branch of theoretical population genetics that models the transmission of genes and cultural traits from one generation to the next, exploring how they interact. These models have been employed to examine the adaptive advantages of learning and culture, to investigate the forces of cultural change, to partition the variance in complex human behavioral and personality traits, and to address specific cases in human evolution in which there is an interaction between genes and culture.

Feldman, M. W. and Zhivotovsky, L. A. Gene-culture coevolution: toward a general theory of vertical transmission. Proc Natl Acad Sci U S A. 1992 Dec 15; 89(24):11935-8.
Abstract: A general formulation of cultural and genetic transmission is developed. The cultural transmission is vertical and the genetics may involve multiple loci. Each individual is represented by a phenogenotype, and conditions are given under which the evolutionary dynamics of phenogenotype frequencies are reducible to phenogametic or phenoallelic frequencies. The interaction between genes and culture is specified by an association measure, and results on the order of magnitude of this association at equilibrium are presented.

Findlay, C. S. Phenotypic Evolution Under Gene-Culture Transmission in Structured Populations. Journal of Theoretical Biology. 1992 Jun 7; 156(3):387-400.

Laland, K. N. Sexual Selection With a Culturally Transmitted Mating Preference. Theoretical Population Biology. 1994 Feb; 45(1):1-15.
Abstract: Culturally transmitted mating preferences may generate sexual selection in human and protocultural animal species if they influence the intensity of selection on genetically transmitted physical and behavioral traits. Haploid and diploid two- ''locus'' models of sexual selection are presented in which mating preferences are culturally transmitted, while traits are transmitted genetically. The models exhibit dynamics similar to those of conventional haploid models of sexual selection, generating neutrally stable curves of equilibrium trait and preference frequencies. A culturally transmitted preference that reaches a significant frequency through cultural drift, individual learning, or social transmission can drag a less viable trait to fixation, or non-zero frequencies. Simulations suggest that strong biases in the transmission of preferences could take initially rare, less viable traits to fixation in as few as 20 to 50 generations, and weak biases in less than 100 generations. These conclusions hold for both biparental and maternally inherited mating preferences. Given the pervasiveness of cultural influences on human mate choice, the analysis suggests that this interaction may have played an important role in human evolution. (C) 1994 Academic Press, Inc.


Laland, K. N., J. Kumm, J. D. Van Horn, and M. W. Feldman. 1995. A gene-culture model of human handedness. Behav Genet 25:433-45.
Abstract: A model of handedness incorporating both genetic and cultural processes is proposed, based on an evolutionary analysis, and maximum-likelihood estimates of its parameters are generated. This model has the characteristics that (i) no genetic variation underlies variation in handedness, and (ii) variation in handedness among humans is the result of a combination of cultural and developmental factors, but (iii) a genetic influence remains since handedness is a facultative trait. The model fits the data from 17 studies of handedness in families and 14 studies of handedness in monozygotic and dizygotic twins. This model has the additional advantages that it can explain why monozygotic and dizygotic twins and siblings have similar concordance rates, and no hypothetical selection regimes are required to explain the persistence of left handedness.

Takahasi, K. and Aoki, K. 2-Locus Haploid and Diploid Models for the Coevolution of Cultural Transmission and Paternal Care. American Naturalist. 1995 Nov; 146(5):651-684.
Abstract: The coevolution of cultural transmission and paternal care is investigated using two-locus haploid and diploid population genetic models. Maternal care of offspring is the rule in mammals, whereas paternal involvement is often minimal. If the biological father also provides care and his continued presence facilitates the transfer of adaptive cultural information, then the conditions for the initial spread of a genetic capacity for cultural transmission are easily satisfied. Conversely, a genetic tendency for the biological father to provide care rather than to desert his mate is more likely to evolve if his role in enculturation is especially important. These predictions derived from the mathematically simpler haploid model are seen to hold approximately for the more realistic diploid model. If the reliability of paternity is low, so that faithful males often direct care and cultural information at unrelated infants, the evolution of cultural transmission and paternal care are both unlikely to occur. We speculate that the evolution of cultural transmission and the nuclear family may have been linked in the hominid line.


Others (not recommended for reading; either old, duplicates of ideas, or difficult to read)
Cavalli-Sforza, L. L. and Feldman, M. W. Cultural transmission and evolution: a quantitative approach. Princeton, New Jersey: Princeton University Press; 1981.

Kumm, J. and M. W. Feldman. 1997. Gene-culture coevolution and sex ratios: II. Sex-chromosomal distorters and cultural preferences for offspring sex. Theor Popul Biol 52:1-15.
Abstract: Cultural preferences for the sex of offspring may produce behavior, such as female infanticide, sex-selective abortion and sex-selective parental investment, which alter the sex ratio in a population. Empirical evidence suggests that some genetic sex-ratio distorters are located on the sex chromosomes. Interactions between cultural preferences and sex-linked sex-ratio distorters are examined. Criteria for the spread of cultural preferences and sex-chromosomal distorter alleles are derived analytically, and the coevolution of preferences and distorters is examined through numerical iteration. Evolutionary equilibria and trajectories of gene-culture interactions involving sex- chromosomal distorter alleles may produce severely male- or female- biased primary sex ratios and adult sex ratios in populations. Adult sex ratios, primary sex ratios, allele frequencies and the prevalence of cultural preferences in the population are sensitive to initial conditions and cultural transmission parameters. During the coevolutionary process phenoallelic association is observed in many cases and is associated with unusual dynamics.

Kumm, J., K. N. Laland, and M. W. Feldman. 1994. Gene-culture coevolution and sex ratios: the effects of infanticide, sex-selective abortion, sex selection, and sex-biased parental investment on the evolution of sex ratios. Theor Popul Biol 46:249-78.
Abstract: The evolutionary consequences of culturally transmitted practices that cause differential mortality between the sexes, thereby distorting the sex ratio (e.g., female infanticide and sex-selective abortion), are explored using dynamic models of gene-culture coevolution. We investigate how a preference for the sex of offspring may affect the selection of genes distorting the primary sex ratio. Sex-dependent differences in mortality have been predicted to select for a male- or female-biased primary sex ratio, to have no effect, or to favor either under different circumstances. We find that when a mating pair's behavior modifies mortality rates in favor of one sex, but does not change the number of offspring produced in the mating, the primary sex ratio will evolve a bias against the favored sex. However, when the total number of offspring of a mating pair is significantly reduced as a consequence of their prejudice, the primary sex ratio will evolve to favor the preferred sex. These results hold irrespective of whether the sex ratio is distorted by the mother's, the father's or the individual's own autosomal genes. The use of dynamic models of gene- culture coevolution allows us to explore the evolution of alleles which distort the sex ratio, as well as the final equilibrium states of the system. Gene-culture interactions can provide equilibria different from those in purely genetic systems, slow the approach to these equilibria by orders of magnitude, and move the primary (PSR) and the adult sex ratio (ASR) away from any stable equilibrium for hundreds of generations.

Tuljapurkar, S., N. Li, and M. W. Feldman. 1995. High sex ratios in China's future. Science 267:874-6.
Abstract: In China in recent years, male live births have exceeded those of females by amounts far greater than those that occur naturally in human populations, a trend with significant demographic consequences. The resulting imbalance in the first-marriage market is estimated to be about 1 million males per year after 2010. These "excess" males were not easily accommodated in models with substantial changes in first- marriage patterns. The current sex ratio at birth has little effect on a couple's probability of having at least one son, so future increases in the sex ratio may well occur, especially given increasing access to sex-selective abortion.