Cultural Evolution Research Paper

1. What Is Cultural Evolution?

First, there is debate over what the expression ‘cultural evolution’ refers to. What is it that evolves? This domain of debate is hardly surprising since ‘culture’ itself is notoriously difficult to define and delimit. Historically, however, the issues here cluster around two main schools of thought. One school follows a broad, holistic definition of cultural evolution that includes changes over space and time in the combined cultural and social systems of a human population. This definition covers big terrain, including both people’s values, ideas, and beliefs—the ideational phenomena of cultures—as well as the organization and structure of societies (as reflected in the size and centralization of polities, the degree of stratification, level of social integration, and so on). This school looks for either universal tendencies across vast expanses of space, time, and human experience— so-called ‘general evolution’—or for variable trajectories of change within particular societies or groups of societies— ‘specific evolution.’ Credible examples of this approach include Johnson and Earle (1987) and Sahlins and Service (1960). Today, the first school is commonly called ‘social evolution’.

The other school takes a narrower definition of cultural evolution and focuses on the dynamics of change in the ideational systems of populations. This school attempts to trace the history of ideas, values, and beliefs that are held by groups of people, and to ask what processes have guided the historical trajectories of change in these phenomena? What processes have made certain ideas and beliefs prominent, in the sense of being widely held and acted on within a group, and others ephemeral or unimportant? This school is sometimes described by analogy: if one regards the cultural system of a human population as a collection of socially transmitted texts in the minds of culture bearers then one can ask, what is the social history of these texts? How were they written and rewritten, and by whom? What are the main processes and actors that have historically edited the texts? And so on. Such questions today are at the heart of this school of cultural evolution, sometimes called ‘evolutionary culture theory’ (Durham 1990, 1992). This second school, focused on socially-transmitted information in human populations—though not exclusive of socially-conveyed information in nonhuman populations (see, for example, Bonner 1980, Heyes and Galef 1996, Wrangham et al. 1994)—is the topic of the remainder of this research paper.

2. In What Sense Do Cultural Systems Evolve?

A second question in cultural evolution concerns the meaning of ‘evolution’ itself, another one of those words that can mean many different things. Curiously, the word ‘evolution’ has had two quite different categories of meanings as it applies to the study of culture change. First, the term has referred to predictable trajectories of change in the social and cultural properties of human populations. In this category, evolution has been taken to mean stage-wise progression from earlier to later forms through regular transitional steps. This meaning of evolution is especially prevalent in the unilinear trajectories (e.g., from simple to complex, from sexual promiscuity to the conjugal family, from savagery to civilization, etc.) of the ‘classical evolutionists’ of the nineteenth century (e.g., John Lubbock, Henry S. Maine, John F. McClennan, Herbert Spencer, Edward E. Tylor—reviewed in Stocking 1987). A similar meaning of the term is also found among so-called ‘neo-evolutionists’ of the twentieth century (including Leslie White, Julian Steward, Elman Service, and Kent Flannery), who commonly propose parallel, multilinear trajectories of change (reviewed Sanderson 1990). Because these arguments, old and new, feature the changing social organization of populations, again they are more commonly called ‘social evolution’ today.

The second category of meanings for cultural evolution features a close analog of Darwin’s original definition, ‘decent with modification,’ only as it applies to the cultural (ideational) features of distinct populations. Here the focus is on transformational change either as (a) one cultural system changes over time and space; (b) one cultural system differentiates into two or more distinct systems; or (c) two or more cultural systems merge into one new one. The first of these transformations (a) is also called cultural ‘microevolution’—change within a given cultural system over time. The second and third transformations, (b) and (c) together, comprise what is sometimes called cultural ‘macroevolution’—that is, pattern and process in the diversification (or homogenization) of new cultural systems either through the division (branching) of one system or the fusion (reticulation) of two or more cultural systems. The remainder of this research paper focuses on cultural microevolution.

3. What Causes Cultural Microevolution?

This third question, what causes change within a given cultural system over time, is an area of active research and discussion in the social sciences. The question en-tails at least two main areas of contemporary debate. The first debate concerns the nature of the elements of which cultural (ideational) systems are composed—the so-called ‘units of culture.’ If cultural systems are composed of socially transmitted information, so the argument goes, then what exactly are the dimensions and properties of the information under conveyance? Are cultural phenomena best modeled as fairly uni-form little pieces or ‘particles’ during social conveyance? Or is it more accurate to view cultures as interconnected systems or hierarchies of information that do not readily ‘chunk’ into uniform small pieces during social transmission? This productive, ongoing debate (reviewed in Weingart et al. 1997) has spawned what might be called another school of cultural evolution theory—the ‘meme’ school, or ‘mimetics.’ Mimetics considers cultural systems to be little more than aggregations of ‘cultural viruses’ that human (or nonhuman) minds as their hosts. The debate has been useful for drawing attention to several interrelated questions, all without clear answers at the time of writing. If cultural histories are replete with ‘viral outbreaks,’ have culture carriers evolved a diversity of immune (protective) responses? If so what are these immune systems and how do they work? Are they effective enough to prevent people’s thoughts and actions from being governed by ‘selfish memes?’ To the extent that cultural evolution favors selfishness on the part of cultural entities, genetic and cultural evolution are predicted to show divergent tendencies (Durham 1991). How often does this occur, in what contexts, and with what outcomes? The implications are clearly substantial for the social sciences: there is a pressing need for more good work in this area.

The second big area of debate concerns alternative models and processes for understanding the ‘editing activity’ of cultural microevolution. The challenge that has emerged from this debate is to identify that process or processes that are akin to Darwin’s ‘main motor’ of biological evolution, natural selection. Looking across the vast expanses in space and time of cultural conveyance in human populations (or non-human), what process or processes have served as ‘editor in chief ? ’ Also, does the role of ‘editor in chief ’ vary in predictable ways by circumstance, as defined by ecological, sociopolitical, and economic conditions? A wide range of different approaches have appeared in recent years to answer these questions; useful views and reviews include Cronk (1999), Durham et al. (1997).

One good way to summarize some of today’s leading models, but by no means the only good way, is according to the models of other processes that inspired them. One approach, for example, called an ‘epidemiology of representations’ (Sperber 1996), draws its inspiration from models and theories governing the spread of contagious disease in host populations. It regards cultural systems as ‘contagions of ideas’ that spread through human population under the guiding influence of ecological and psychological conditions. In this epidemiological model:

All the information that humans introduce into their common environment can be seen as competing for private and public space and time—that is, for attention, internal memory, transmission, and external storage. Many factors affect the chances of some information being successful and reaching a wide and lasting level of distribution, of being stabilized in a culture …. The most general psychological factor affecting the distribution of information is its compatibility and fit with human cognitive organization. (Sperber 1996, p. 140)

The approach has much to recommend it: certainly many cultural phenomena spread ‘horizontally’ (be-tween peers) within societies, like fads and fashions; certainly the success of contagious cultural elements depends to some extent on their psychological appeal or attraction; and surely cognitive processes in individual minds actively transform the ‘contagion’ as it spreads. The challenge to this approach remains to illustrate by theory and example the relative force of psychological attraction compared to other forces, and to produce convincing empirical examples across a spectrum of cultural phenomena (for one example, see Boyer 1994).

A second approach uses the term ‘coevolution’ to develop a model of cultural evolution that is explicitly parallel to, though different from, Darwinian theory in biology (Durham 1991). The model views human populations as having two ‘inheritance systems,’ one genetic and one cultural. Each form of inheritance is conceptualized as having its own channel of information transmission, one consisting of genes passed along via reproduction and the other consisting of ideational phenomena (ideas, values, beliefs) passed along via social transmission. Each form of inheritance is subject to a variety of processes producing change over space and time. In the genetic channel, these processes include the familiar Darwinian foursome: mutation, migration, drift (chance fluctuations), and differential reproduction or ‘natural selection.’ In the cultural channel, coevolutionary theory proposes the roughly analogous processes of innovation, diffusion (with or without migration), cultural drift, natural selection (cultural change via differential reproduction), and cultural selection (change through value-driven decision making by culture carriers). Durham’s formulation (1991, p. 198) emphasizes the role of human beings as decision makers:

Provided they are given both a range of options and an opportunity to choose, people can participate in the trans-mission process as selecting agents. In other circumstances, where options and choice are largely pre-empted [by power relations], cultural evolution may still be guided by human decisions—that is, by the imposed decisions of powerful individuals or groups. But either way, culture changes under ‘human’ direction; people, not ‘nature’ do most of the selecting.

The strengths of this approach are several: it builds social structure and asymmetrical power relations into the evolutionary dynamics of cultural change; it emphasizes key similarities and differences with bio-logical evolutionary theory without overly ‘Darwinizing’ cultural dynamics; and it provides a ready explanation for the culturally-guided directionality so characteristic of cultural evolution. In Durham’s view, the most important values governing the decision-making processes are previously evolved ‘cultural’ values. Further the framework has particular value in analytical applications (see Durham 1992). While not as quantitative as other models, it has been useful in more and more thorough empirical analyses than the other formulations.

The third approach was also the first historically, and the most quantitative. Taking its main inspiration from Mendel, mixed with influence from Darwin and epidemiology, the approach focuses on the cultural transmission process and the ways in which the context of transmission (who teaches, who learns) produces evolutionary change in cultural systems (Cavalli-Sforza and Feldman 1981). Quantitative models have been proposed for three different contexts of social transmission: vertical (meaning from parents to off-spring), oblique (from nonparents of one generation to offspring in the next), and horizontal (among peers of the same generation). The models predict, among a variety of other things, that vertical transmission is generally most conservative in its evolutionary effects (i.e., causing least change from generation to generation) while horizontal transmission promotes relatively rapid evolutionary change—a finding nicely corroborated in a later empirical studies (see, e.g., Hewlett and Cavalli-Sforza 1986). These baseline models have been modified and extended to include conformity effects, continuous traits, and group-level selection. Similar transmission models developed by Boyd and Richerson (1985), also drawing inspiration from Mendel, emphasize various forms of ‘bias’ that can result from variability in the context of social transmission. In ‘indirectly biased transmission,’ for example, individuals are viewed as adopting for themselves the cultural variants that are used or exhibited by ‘successful’ individuals whom they emu-late. Boyd and Richerson show how this biasing mechanism can lead to the unstable ‘runaway’ cultural evolution of highly exaggerated features (such as growing huge yams or participating in elaborate tattooing, in the examples they offer). In ‘frequency dependent biased transmission,’ individuals adopt for themselves the most common or most popular cultural variant in a population, a process that readily leads to conformist effects. An interesting result of conformist transmission is that it may increase the magnitude of intergroup differences, potentially contributing to differential rates of group-level survival and propagation (i.e., group selection, see Boyd and Richerson 1985, Chap. 7).

In a further extension of so-called transmission models, Feldman and Cavalli-Sforza, and Aoki after them, proposed a combination model that allows genetic and cultural transmission to produce joint ‘genophenotypes’ which can then be used to model coevolutionary dynamics. Recently, Laland et al. (2000), building on Durham (1991), have added self-induced habitat change, or ‘niche construction,’ to the inter-active processes of biological and cultural evolution. The schema formally recognizes the way that cultural processes produce long-lasting habitat modifications, thus providing a kind of ‘environmental inheritance’ that permits human beings to ‘co-direct our own evolution.’

In conclusion, one may fairly state that theories of cultural evolution themselves continue to undergo rapid evolutionary change. Their potential value to social science is substantial, particularly if they eventually help to bridge the intellectual gap between biological and social sciences. Further theoretical developments will surely contribute to the bridge, but good empirical analyses and longitudinal case studies will probably be even more persuasive. At the time of writing, theories of cultural evolution remain surprisingly peripheral to mainstream social science. Hopefully that, too, will change.

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