Cultural evolution developing its own rules--论文代写范文精选

文化是在多大程度上影响我们的基因已经被人类和生物科学的一个重要课题,这仍然有强烈争论。一些生物学家、进化心理学家认为文化是严格控制由遗传决定,而另一些人则认为文化和基因进化不同但相互作用，共同决定人类行为。下面的essay代写范文将进行叙述。

Abstract 
In the human sciences, cultural evolution is often viewed as an autonomous process free of genetic influence. A question that follows is, If culture is not influenced by genes, can it take any path? Employing a simple mathematical model of cultural transmission in which individuals may copy each other’s traits, we show that cultural evolution favors individuals who are weakly influenced by others and able to influence others. The model suggests that the cultural evolution of rules of cultural transmission tends to create populations that evolve rapidly toward conservatism, and that bias in cultural transmission may result purely from cultural dynamics. Freedom from genetic influence is not freedom to take any direction.

Introduction 
The extent to which culture is influenced by our genes has been a major topic in the human and biological sciences and remains strongly debated (Segerstråle, 2000; Laland & Brown, 2002; Rogers, 1988; Richerson & Boyd, 2005). Some biologists and evolutionary psychologists view culture as tightly controlled by a genetically determined human nature (Wilson, 1978; Lumsden & Wilson, 1985; Alexander, 1979; Tooby & Cosmides, 1992), while others see cultural and genetic evolution as distinct but interacting processes that jointly determine human behavior (Boyd & Richerson, 1985; Feldman & Laland, 1996). In the human sciences, cultural evolution is often viewed as an autonomous process essentially free of genetic influence (see e.g. Kroeber, 1917; Geertz, 1965; Science for the People, 1976; Harris, 1979). This view is also common in meme-based approaches to culture (Dennett, 1995; Blackmore, 1999; Laland & Brown, 2002). According to it, genes provide us with the abilities that make culture possible (e.g., learning and language skills) but do not bias culture in any particular direction. Within this debate, this report addresses one general and one specific question. 

The general question is: If culture is not influenced by genes, can it take any path? We believe that the answer is no because culture itself harbors forces that favor some outcomes relative to others. We make this point by considering some specific forces that arise from the process of cultural transmission. We employ a simple mathematical model of cultural transmission in which individuals may copy each other’s cultural traits, including traits that can affect the copying process itself. In particular, we consider as cultural traits the extent to which individuals are prepared to imitate others (“openness”) and the extent to which they are able to persuade others to adopt their own cultural traits (“persuasion”). In the model, these traits affect their own transmission as well as the transmission of other traits. 

We show that cultural evolution favors individuals who are at once weakly influenced by others and yet able to influence others. We stress that whole in our models individuals have no genetic predispositions toward any trait value (a kind of tabula rasa assumption [see below]), yet definite trends emerge from the very dynamics of culture. We are interested in traits that influence cultural transmission because theoretical studies show that modes of transmission can deeply affect cultural evolution (Campbell, 1975; Cavalli-Sforza & Feldman, 1981; Boyd & Richerson, 1985; Nakamaru & Levin, 2004). For example, the way a belief spreads depends on whether it is transmitted from parent to offspring or between peers (CavalliSforza & Feldman, 1981; Boyd & Richerson, 1985). 

Empirical data also demonstrate many subtleties of cultural transmission, among them imitation of some individuals or behaviors but not others (Bandura, 1986). At the same time, what determines the rules of cultural transmission remains poorly understood. One possibility is that they are genetically programmed (Wilson, 1978; Lumsden & Wilson, 1981). Our models investigate another possibility: that they emerge from cultural evolution.

The modeling framework 
We consider culture a dynamic system whose evolution depends on many forces (Cavalli-Sforza & Feldman, 1981; Boyd & Richerson, 1985; Feldman & Laland, 1996). “Evolution” means here simply “change,” and progress may or may not result. For simplicity, we consider a large, unstructured population in which individuals interact at a given rate. Each interaction involves two randomly chosen individuals, model and observer. The observer may adopt part or all of the cultural type of the model, in which case we say that cultural transmission has occurred. Our aim is to study how transmission changes the distribution of cultural traits in the population and to identify any long-term tendencies. With respect to birth and death, we study two cases. We first assume that individuals live forever. This case is studied mainly for its simplicity, but it may apply to cultural phenomena so rapid that births and deaths are negligible, such as fashions or shifts in political opinion. We then consider deaths and births explicitly. We assume that newborns are maximally open to acquiring culture but otherwise devoid of cultural traits. This recognizes that genes provide newborns with basic functionality such as memory and learning ability, and is consistent with most tabula rasa views (Kroeber, 1917; Geertz, 1965; Quigley, 1979; Rogers, 1988). 

The paradox of “openness” 
Our first model considers the cultural evolution of a single trait, called “openness.” It corresponds to the everyday experience that people differ in the ease with which they change habits and beliefs. Intuition suggests that openness may be an important factor in cultural transmission and evolution. In reality, openness is of course not an atomic aspect of human personality: it arises from the combination of many individual traits, such as one’s attitudes toward traditional lifestyles or the habits of older generations, aspects of personality such as self-confidence and extroversion, and opinions about others in general (e.g., whether they should be trusted). To illustrate our argument, however, we start by modeling openness as a single trait that can be directly transmitted between individuals. Later we consider the more realistic case in which openness changes indirectly as a result of the cultural transmission of other traits.

In our models population reach almost complete conservatism, but this is not true of actual populations. The reasons should be sought in forces that we ignored yet can influence the cultural evolutionary process. For instance, many personality traits are under both environmental and genetic control (Plomin et al. 2000; Laland & Brown 2002; see also “guided variation” in Boyd & Richerson 1985) and it is possible that our genetic constitution does not allow complete conservatism. In such a case a pure tabula rasa hypothesis would not be adequate to study the dynamics of openness. Natural selection and socio-economic processes are examples of other, potent forces that can shape culture (Richerson & Boyd, 2005; Laland et al., 1995; Feldman & Laland, 1996; Bisin & Verdier, 2001). 

We have chosen not to study them in this paper because we wanted to start from a simple case in which the effects of evolvable cultural transmission is not confounded with other forces. Such effects are poorly known and it seemed to us premature to study a complex model before having understood simpler ones. Most mathematical models of cultural evolution assume that how we learn from others is under genetic control (Boyd & Richerson, 1985; Henrich & Boyd, 1998) and do not allow for cultural modification of transmission rules (but see Takahasi, 1998). Richerson & Boyd, for instance, argue that natural selection has injected in our psychology a degree of conformism which improves our ability to choose adaptive cultural traits (Boyd & Richerson, 1985; Richerson & Boyd, 2005). Our arguments show that biases in cultural transmission may result purely from cultural dynamics. Thus even if the genes are not structuring culture, culture structures itself. Freedom from genetic influences is not freedom to take any direction.（essay代写)

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