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- Dual inheritance theory
- Coevolution Genes, Culture, and Human Diversity - William H. Durham (introducción).pdf
- Niche Construction and Gene-Culture Coevolution: An Evolutionary Basis for the Human Sciences
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Dual inheritance theory
Dual inheritance theory DIT , also known as gene—culture coevolution or biocultural evolution ,  was developed in the s through early s to explain how human behavior is a product of two different and interacting evolutionary processes: genetic evolution and cultural evolution.
Genes and culture continually interact in a feedback loop,  changes in genes can lead to changes in culture which can then influence genetic selection, and vice versa. One of the theory's central claims is that culture evolves partly through a Darwinian selection process, which dual inheritance theorists often describe by analogy to genetic evolution. Most of the modelling done in the field relies on the first dynamic copying though it can be extended to teaching. Social learning at its simplest involves blind copying of behaviors from a model someone observed behaving , though it is also understood to have many potential biases , including success bias copying from those who are perceived to be better off , status bias copying from those with higher status , homophily copying from those most like ourselves , conformist bias disproportionately picking up behaviors that more people are performing , etc..
Understanding social learning is a system of pattern replication, and understanding that there are different rates of survival for different socially learned cultural variants, this sets up, by definition, an evolutionary structure: cultural evolution.
Because genetic evolution is relatively well understood, most of DIT examines cultural evolution and the interactions between cultural evolution and genetic evolution. DIT holds that genetic and cultural evolution interacted in the evolution of Homo sapiens.
DIT recognizes that the natural selection of genotypes is an important component of the evolution of human behavior and that cultural traits can be constrained by genetic imperatives. However, DIT also recognizes that genetic evolution has endowed the human species with a parallel evolutionary process of cultural evolution. DIT makes three main claims: .
The human capacity to store and transmit culture arose from genetically evolved psychological mechanisms. This implies that at some point during the evolution of the human species a type of social learning leading to cumulative cultural evolution was evolutionarily advantageous. Social learning processes give rise to cultural evolution. Cultural traits are transmitted differently from genetic traits and, therefore, result in different population-level effects on behavioral variation.
Cultural traits alter the social and physical environments under which genetic selection operates. For example, the cultural adoptions of agriculture and dairying have, in humans, caused genetic selection for the traits to digest starch and lactose , respectively. This refinement may have further influenced the way culture is stored and the biases that govern its transmission.
DIT also predicts that, under certain situations, cultural evolution may select for traits that are genetically maladaptive. An example of this is the demographic transition , which describes the fall of birth rates within industrialized societies. Dual inheritance theorists hypothesize that the demographic transition may be a result of a prestige bias, where individuals that forgo reproduction to gain more influence in industrial societies are more likely to be chosen as cultural models.
People have defined the word "culture" to describe a large set of different phenomena. Culture is socially learned information stored in individuals' brains that is capable of affecting behavior. This view of culture emphasizes population thinking by focusing on the process by which culture is generated and maintained. It also views culture as a dynamic property of individuals, as opposed to a view of culture as a superorganic entity to which individuals must conform.
Genes affect cultural evolution via psychological predispositions on cultural learning. Genes constrain the brain's structure and, hence, the ability of the brain to acquire and store culture. Genes may also endow individuals with certain types of transmission bias described below. One of the best known examples is the prevalence of the genotype for adult lactose absorption in human populations, such as Northern Europeans and some African societies, with a long history of raising cattle for milk.
Until around 7, years ago,  lactase production stopped shortly after weaning,  and in societies which did not develop dairying, such as East Asians and Amerindians, this is still true today. Culture has driven changes to the human digestive systems making many digestive organs, like our teeth or stomach, smaller than expected for primates of a similar size,  and has been attributed to one of the reasons why humans have such large brains compared to other great apes.
Early examples of food processing include pounding, marinating and most notably cooking. Pounding meat breaks down the muscle fibres, hence taking away some of the job from the mouth, teeth and jaw. Cooking partially breaks down food making it more easily digestible. Food enters the body effectively partly digested, and as such food processing reduces the work that the digestive system has to do. This means that there is selection for smaller digestive organs as the tissue is energetically expensive,  those with smaller digestive organs can process their food but at a lower energetic cost than those with larger organs.
Humans living on cooked diets spend only a fraction of their day chewing compared to other extant primates living on raw diets. American girls and boys spent on average 8 and 7 percent of their day chewing respectively, compared to chimpanzees who spend more than 6 hours a day chewing. A raw diet means hunting is constrained since time spent hunting is time not spent eating and chewing plant material, but cooking reduces the time required to get the day's energy requirements, allowing for more subsistence activities.
Despite its benefits, brain tissue requires a large amount of calories, hence a main constraint in selection for larger brains is calorie intake. A greater calorie intake can support greater quantities of brain tissue. This is argued to explain why human brains can be much larger than other apes, since humans are the only ape to engage in food processing. It is this that allowed for the brain expansion, independent of cooking which they argue came much later, a consequence from the complex cognition that developed.
Further criticism comes from the controversy of the archaeological evidence available. Some claim there is a lack of evidence of fire control when brain sizes first started expanding. Also at this time was a narrowing of the pelvis indicating a smaller gut and also there is evidence that there was a loss of the ability to climb which Wrangham argues indicates the control of fire, since sleeping on the ground needs fire to ward off predators.
In DIT, the evolution and maintenance of cultures is described by five major mechanisms: natural selection of cultural variants, random variation, cultural drift, guided variation and transmission bias.
Cultural differences among individuals can lead to differential survival of individuals. The patterns of this selective process depend on transmission biases and can result in behavior that is more adaptive to a given environment. Random variation arises from errors in the learning, display or recall of cultural information, and is roughly analogous to the process of mutation in genetic evolution. Cultural drift is a process roughly analogous to genetic drift in evolutionary biology. This effect should be especially strong in small populations.
Cultural traits may be gained in a population through the process of individual learning. Once an individual learns a novel trait, it can be transmitted to other members of the population. The process of guided variation depends on an adaptive standard that determines what cultural variants are learned. Understanding the different ways that culture traits can be transmitted between individuals has been an important part of DIT research since the s.
The list of biases has been refined over the years, especially by Henrich and McElreath. Content biases result from situations where some aspect of a cultural variant's content makes them more likely to be adopted. For example, food preferences can result from genetic preferences for sugary or fatty foods and socially-learned eating practices and taboos. Context biases result from individuals using clues about the social structure of their population to determine what cultural variants to adopt.
This determination is made without reference to the content of the variant. There are two major categories of context biases: model-based biases, and frequency-dependent biases. Model-based biases result when an individual is biased to choose a particular "cultural model" to imitate.
There are four major categories of model-based biases: prestige bias, skill bias, success bias, and similarity bias. A measure of prestige could be the amount of deference shown to a potential cultural model by other individuals.
A "skill bias" results when individuals can directly observe different cultural models performing a learned skill and are more likely to imitate cultural models that perform better at the specific skill.
A "success bias" results from individuals preferentially imitating cultural models that they determine are most generally successful as opposed to successful at a specific skill as in the skill bias. A "similarity bias" results when individuals are more likely to imitate cultural models that are perceived as being similar to the individual based on specific traits. Frequency-dependent biases result when an individual is biased to choose particular cultural variants based on their perceived frequency in the population.
The most explored frequency-dependent bias is the "conformity bias. Another possible frequency dependent bias is the "rarity bias. The rarity bias is also sometimes called a "nonconformist" or "anti-conformist" bias. In DIT, the evolution of culture is dependent on the evolution of social learning. Analytic models show that social learning becomes evolutionarily beneficial when the environment changes with enough frequency that genetic inheritance can not track the changes, but not fast enough that individual learning is more efficient.
It is only in the moderately changing environment where cultural learning becomes useful since each generation shares a mostly similar environment but genes have insufficient time to change to changes in the environment. They propose that the environmental changes occurring in the Pleistocene may have provided the right environmental conditions.
Although group selection is commonly thought to be nonexistent or unimportant in genetic evolution,    DIT predicts that, due to the nature of cultural inheritance, it may be an important force in cultural evolution. Group selection occurs in cultural evolution because conformist biases make it difficult for novel cultural traits to spread through a population see above section on transmission biases.
Conformist bias also helps maintain variation between groups. These two properties, rare in genetic transmission, are necessary for group selection to operate. Analysis of small groups in New Guinea imply that cultural group selection might be a good explanation for slowly changing aspects of social structure, but not for rapidly changing fads.
The idea that human cultures undergo a similar evolutionary process as genetic evolution goes back at least to Darwin  In the s, Donald T.
Campbell published some of the first theoretical work that adapted principles of evolutionary theory to the evolution of cultures. In that year Richard Dawkins's The Selfish Gene introduced ideas of cultural evolution to a popular audience. Although one of the best-selling science books of all time, because of its lack of mathematical rigor, it had little effect on the development of DIT. Also in , geneticists Marcus Feldman and Luigi Luca Cavalli-Sforza published the first dynamic models of gene—culture coevolution.
The first was Charles Lumsden and E. Wilson's Genes, Mind and Culture. While it was the first book published describing how genes and culture might coevolve, it had relatively little effect on the further development of DIT. It describes the evolutionary implications of vertical transmission , passing cultural traits from parents to offspring; oblique transmission, passing cultural traits from any member of an older generation to a younger generation; and horizontal transmission , passing traits between members of the same population.
The book's conclusion also outlined areas for future research that are still relevant today. This agenda, outlined below, called for the development of both theoretical models and empirical research.
DIT has since built a rich tradition of theoretical models over the past two decades. In a interview Harvard biologist E. Wilson expressed disappointment at the little attention afforded to DIT:. Until such a time as the theoretical hieroglyphics can be translated into a respectable empirical science most observers will remain immune to its message.
Economist Herbert Gintis disagrees with this critique, citing empirical work as well as more recent work using techniques from behavioral economics. Since one of the goals of DIT is to explain the distribution of human cultural traits, ethnographic and ethnologic techniques may also be useful for testing hypothesis stemming from DIT. Although findings from traditional ethnologic studies have been used to buttress DIT arguments,   thus far there have been little ethnographic fieldwork designed to explicitly test these hypotheses.
Coevolution Genes, Culture, and Human Diversity - William H. Durham (introducción).pdf
Dual inheritance theory DIT , also known as gene—culture coevolution or biocultural evolution ,  was developed in the s through early s to explain how human behavior is a product of two different and interacting evolutionary processes: genetic evolution and cultural evolution. Genes and culture continually interact in a feedback loop,  changes in genes can lead to changes in culture which can then influence genetic selection, and vice versa. One of the theory's central claims is that culture evolves partly through a Darwinian selection process, which dual inheritance theorists often describe by analogy to genetic evolution. Most of the modelling done in the field relies on the first dynamic copying though it can be extended to teaching. Social learning at its simplest involves blind copying of behaviors from a model someone observed behaving , though it is also understood to have many potential biases , including success bias copying from those who are perceived to be better off , status bias copying from those with higher status , homophily copying from those most like ourselves , conformist bias disproportionately picking up behaviors that more people are performing , etc.. Understanding social learning is a system of pattern replication, and understanding that there are different rates of survival for different socially learned cultural variants, this sets up, by definition, an evolutionary structure: cultural evolution.
Perspectives in Ethology pp Cite as. Traditionally evolutionary theory treats the adaptations of organisms as consequences of a process whereby natural selection moulds organisms to fit pre-established environments. The changes that organisms themselves cause in their own environments are seldom through to be evolutionarily significant. In this chapter, we build on conventional evolutionary theory by adding niche construction. We argue that the resulting enhanced theory of evolution provides a better basis for understanding how human cultural processes interact with human genetic processes in human evolution, and we discuss how human cultural niche construction may have co-directed, and may still be co-directing, human genetic evolution. Unable to display preview.
Coevolution: Genes, culture, and human diversity. By William H. Durham. Stanford, CA: Stanford University Press. xxii + pp. ISBN 0‐‐‐8.
Niche Construction and Gene-Culture Coevolution: An Evolutionary Basis for the Human Sciences
In an era of globalization everybody talks about diversity, but how much do you actually know about human nature and human diversity? Why is there so much diversity in sex and gender, race, diet, morality and norms, political views, religious beliefs, cognition, perceptions, and emotions? Is this just human nature? Are there any universals in human nature?
Humans possess an extraordinary capacity for culture, from the arts and language to science and technology. But how did the human mind—and the uniquely human ability to devise and transmit culture—evolve from its roots in animal behavior? This compelling and accessible book reveals how culture is not just the magnificent end product of an evolutionary process that produced a species unlike all others—it is also the key driving force behind that process.
Don't have an account? Humans shared a last common ancestor with the chimpanzee and the bonobo at least 7 million years ago. The hominin clade has included many species, some of which will have co-existed. Few are in direct ancestral relationship to Homo sapiens. Humans are distinguished from the other great apes by specific physical bipedalism, brain size, hairlessness and cultural tool making, language, society traits.
Используя вместо классной доски салфетки ресторана Мерлутти или концертные программы, Сьюзан дала этому популярному и очень привлекательному преподавателю первые уроки криптографии. Она начала с совершенного квадрата Юлия Цезаря. Цезарь, объясняла она, был первым в истории человеком, использовавшим шифр. Когда его посыльные стали попадать в руки врага имеете с его секретными посланиями, он придумал примитивный способ шифровки своих указаний. Он преобразовывал послания таким образом, чтобы текст выглядел бессмыслицей. Что, разумеется, было не. Каждое послание состояло из числа букв, равного полному квадрату, - шестнадцати, двадцати пяти, ста - в зависимости оттого, какой объем информации нужно было передать.