Abstracts and Readings for IPEM Winter/Spring 2008 Seminar Series
Crows and cavemen: An evolving coevolution of culture
John Marzluff
College of Forest Resources
University of Washington
I am interested in the general issue of how humans and nature affect one-another. Here, I explore how genetic and cultural evolution generally allow human and other species' to become co-evolved. I use past and ongoing interactions between people and crows to suggest that when humans interact with other social species, who themselves have the ability to evolve culture, then simple feedbacks from a culturally evolving "environment" can stimulate rapid cultural evolution in humans. I term the reciprocal adjustments in two or more species' cultures "cultural coevolution." Cultural coevolution may involve genetic fitness benefits or may depend on migration and the diffusion of ideas, cultural drift, differential modeling and role selection, or societal choice and imposition, all of which are important to cultural evolution. I review our long history of interaction with crows and ravens (aka corvids) and discuss the results of new experiments that illustrate the breadth of cultural coevolution and some of its mechanisms. Our new experiments illustrate that American crows (Corvus brachyrhynchos) are able to recognize the faces of humans with whom they have had past negative interactions. Social learning appears to facilitate this ability and may enable cultural adjustments by crows to specific people. Such ability to recognize individual people and adjust current behavior based on past experience may enable crows and people to mutually coevolve.
Suggested Reading
Social networks: An introduction for evolutionary modelers
Steve Goodreau
Department of Anthropology
University of Washington
Social network analysis seeks to understand the structure of social relations among the members of a population. It is a broad interdisciplinary field, with roots in mid-20th century British anthropology and many other fields, and with existing applications in all of the social and biological sciences. More recently, the field has undergone major methodological advances; through the use of microsimulation and advanced statistical methods, network analysts can now identify the underlying processes generating observed networks, simulate the emergence of complex structures from simple local rules, and explore the effects that network structure has on the flow of information, behavioral norms, disease, support, or other socially exchanged goods through a population. In this talk I will provide a broad overview to the field, with an emphasis on those strands I believe to be of greatest potential interest to evolutionary modelers. My hope is that this will lead us to some fruitful brainstorming about ways this framework may help to address unanswered questions about human cultural and biological evolution.
Suggested Reading
Kinship dynamics, reproductive competition and the evolution of menopause
Rufus Johnstone
Department of Zoology
University of Cambridge
Human females stop reproducing long before they die. Among other mammals, only pilot and killer whales exhibit a comparable period of post-reproductive life. The grandmother hypothesis suggests that kin selection can favour post-reproductive survival when older females help their relatives to reproduce. But although there is evidence that grandmothers can provide such assistance, it is puzzling why menopause should have evolved only among the great apes and toothed whales. Here, we offer a simple explanation based on kinship dynamics. We show that the genetic relatedness of a breeding female to others in her social group will change across her lifespan in a manner that depends on patterns of mating and dispersal, and we derive general formulae for these kinship dynamics in a group-structured population. Male-biased dispersal leads to a decrease in local relatedness with female age, so that reproductive restraint and helping behaviour are favoured more strongly earlier in life. By contrast, when dispersal is female-biased or when neither sex disperses but mating occurs outside the group, local relatedness increases with female age, so that reproductive restraint and helping are favoured more strongly later in life. Most mammals exhibit male-biased dispersal. By contrast, most great apes show female-biased dispersal, a pattern that likely characterized ancestral humans, while in pilot and resident killer whales neither sex disperses but mating occurs outside the local group. Kinship dynamics can thus explain why, of all long-lived, social mammals, it is specifically among the great apes and toothed whales that menopause and post-reproductive helping have evolved.
Suggested Reading
Mace, Ruth (2000) Evolutionary ecology of human life history. Animal Behaviour 29:1-10.
Reputation, reciprocity and large-scale cooperation
Karthik Panchanathan
Department of Anthropology
University of California, Los Angeles
Understanding the evolution of large-scale cooperation, one of the hallmarks of humanity, continues to be a thriving research topic. Any explanation must account for how cooperation can persist in the face of would-be free riders. Many evolutionary and social scientists assert that some combination of reputation and reciprocity are sufficient explanations, citing, for example, Axelrod & Hamilton's (1981) work on "reciprocal altruism" and Nowak & Sigmund's (1998) work on "indirect reciprocity". In this talk, I will present theoretical models and ask whether this claim―that reputation and reciprocity are sufficient explanations of large-scale cooperation―is logically cogent. Spoiler alert: The answer, it turns out somewhat anti-climactically, is that it depends on the assumptions one makes. The interesting question then becomes whether or not such assumptions are reasonable and whether this kind of mechanism does, in fact, explain the evolution and persistence of large-scale cooperation. If time permits, I'll present an additional model that takes for granted that reputation stabilizes cooperation and then show that this mechanism acts in a conservative manner. By that I mean that whatever social norm first becomes common persists; more beneficial social norms cannot arise by within-group selection.
Suggested Reading
Panchanathan, Karthik and Rob Boyd (2004) Supplementary online materials. Nature 432.
Broken telephones, virtual arrowheads and cultural evolution: How cultural transmission experiments can inform an evolutionary science of human culture
Alex Mesoudi
Department of Social and Developmental Psychology
University of Cambridge
Experimental methods from social psychology can be used to simulate cultural transmission in the lab, allowing us to investigate specific content biases, or simulate the details of who copies what from whom. For example, Mesoudi, Whiten & Dunbar (2006) found that information about third-party social relationships was transmitted with greater accuracy and in greater quantity than equivalent non-social information, consistent with "social brain" hypotheses concerning the evolution of human cognition. Such findings can be used to inform a theory of cultural evolution, the idea that human culture changes in a manner comparable to that in which biological species evolve (Mesoudi, Whiten & Laland 2004, 2006). Cultural transmission experiments, which reveal the micro-evolutionary details of who copies what from whom and how, can be extrapolated to the population level in order to explain long-term and large-scale aspects of cultural change (Mesoudi 2007), just as evolutionary biologists extrapolate from the microevolutionary forces of natural selection, sexual selection, drift etc. up to biological macroevolution. For example, Mesoudi & O'Brien (in press) had participants design "virtual arrowheads," with different phases of the experiment simulating either individual trial-and-error learning, which generated low correlations between artifact attributes, or indirectly-biased cultural transmission, which generated high inter-attribute correlations. These correlation patterns match prehistoric projectile points from California and Nevada respectively, giving us insight into the learning processes underlying archaeological data.
Suggested Reading
The rise and fall of cultures: Environmental variation, the evolution of cultural capacity, cultural conformism and societal collapse
Hal Whitehead
Department of Biology
Dalhousie U
I used individual-based evolutionary stochastic models and "1/f" noise to examine the circumstances in which cultural capacity might evolve, and in which cultural capacity might lead to population collapse. The first set of models showed that: when environmental variation has little effect on fitness, then genetic determinism persists; when environmental variation is large and equal over all time scales ("white noise") then individual learning is adaptive; but in "red noise" environments when variation over long time scales is large, social learning is advantageous. Population trajectories of many species, especially large mammals and aquatic carnivores, are sufficiently red to promote social learning in their predators, and the ocean environment is generally redder than that on land. Thus social learning and culture will often be found in species dependent on the populations of other species, especially if they are marine. However, when the environment is red, social learning may become fixed in a population, which thereby loses its ability to track the environment, and so collapses.
Suggested Reading
The evolution of norms and institutions (including cooperative ones): Ethnographic and experimental evidence from Fiji
Joseph Henrich
Departments of Psychology and Economics
University of British Columbia
An immense amount of ethnographic data suggests that across a wide range of human societies individually costly behaviors are sustained by fear of some form of sanctions (and some actual sanctions) administered by other members of one’s group. These are norms. While these norms sometimes include prosocial behaviors, such as cooperative contributions to public goods and fairness toward non-repeat interactants, they also include non-cooperative behaviors that would appear to damage the fitness of both individuals and the group. Recent work in applying evolutionary theory to human learning suggests that a wide variety of cultural evolutionary processes can sustain such norms, though only some of these processes generate the diffuse costly punishment that is prevalent in our own society and has received much recent attention. In this talk I will summarize work on these cultural evolutionary mechanisms and evaluate them competitively, along with other a-cultural evolutionary explanations, using a combination of ethnography and experiments, principally from fieldwork in Fiji. The findings broadly support the idea that cultural evolution has exploited our evolved psychology in quite different ways in concocting a variety of cultural contrivances to sustain norms and spread larger-scale cooperation.
Suggested Reading
Modeling gene-culture coevolution: Some theoretical considerations
William Harms
Department of Philosophy
Seattle Central Community College
One approach to creating a general framework for modeling gene/culture coevolution implements Donald T. Campbell's "nested hierarchy of blind variation and selective retention processes" with a modularized version of the so-called "replicator dynamics" commonly used in Evolutionary Game Theory. On this approach, any arbitrarily designated "population" can be modeled as a variation and selection process, though of course not all populations exhibit interesting behavior. This has certain advantages over the alternative gene/meme coevolution approach, as it obviates difficult questions regarding what qualifies as a meme (or as a gene, for that matter). In actually constructing models of this sort, however, one comes to see that they have difficulties of their own. In particular, genetic traits have their profoundest effect on trait acquisition in the individuals that carry them, and acquired traits have their profoundest effect on the genetic fitness of their owners. Fully adequate models will need to accommodate this, either through the proliferation of subpopulations in the models, or by moving to a fundamentally agent-based framework.
Suggested Reading
Early-modern commodities as costly signals: Clay tobacco pipes in the 17th-century British Atlantic
Fraser Neiman
Department of Archaeology, Monticello
Department of Anthropology, U of Virginia
Historians of the early-modern Atlantic use the phrase "consumer revolution" to denote the advent of mass production and the consumption of commodities. Clay tobacco pipes are among the earliest examples. Signaling theory offers the tools with which to model interactions among Chesapeake pipe consumers, who used certain pipe attributes as unfakable signals of resource holding potential, and English pipe producers who designed pipes to maximize profits. The model offers useful predictions about formal patterning in pipe-stem bore diameter distributions in time and social space, which can be monitored in the archaeological record. These are evaluated using data from 17th-century Jamestown Virginia and other Chesapeake sites..
Suggested Reading
Cultural transmission and social evolution: Prestige, prestige goods, and the emergence of hierarchical social structures
Aimée Plourde
AHRC Centre for the Evolution of Cultural Diversity
University College London
One of the more puzzling aspects of institutionalized social inequality—a quite recent development in human societies relative to other evolved characteristics of our species—is how such structures were 'allowed' to come into being. Social norms constraining boasting and other forms of status striving are common features of contemporary egalitarian groups, for example, and may have been so in past ones as well. Many scholars have highlighted the charismatic aspects of early leaders and the different kinds of persuasive strategies that would-be elites could have used to attract followers and negotiate alliances. Of these, the possession of prestige is often cited, and in particular the use of prestige goods in both personal display and as gifts used to achieve prestige, and thus increased social status power. The correlation between the presence of prestige goods and other indicators of sociopolitical hierarchy in the archaeological record is typically assumed to be due to admiration and desire for such goods as is commonly experienced by people in contemporary societies. Yet this desire in itself requires explanation, given that prestige goods appear at different times and places and fairly late in prehistory. Following Henrich and Gil-White's "information goods" theory, I suggest that prestige goods initially evolved to function as honest (costly) signals of skill and knowledge, in response to increasing levels of prestige competition. The psychological mechanisms underlying this function provide a link to later roles in the development of social status ranking and political hierarchy. Leaders in contemporary transegalitarian societies are selected or accepted from among those with high prestige in expertise relevant to the group's task at hand, shown in part through prestige goods. I theorize that this association between leaders and prestige goods led to an expansion of prestige goods' signal content to include elevated social status and power, and their role in subsequent development of hierarchy.
Suggested Reading