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12 Gene–Culture Coevolution in the Age of Genomics--Peter J. Richerson, Robert Boyd, and Joseph Henrich
Pages 231-256

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From page 231...
... We investigate the hypothesis that the process of cultural evolution has played an active, leading role in the evolution of genes. Culture normally evolves more rapidly than genes, creating novel envi ronments that expose genes to new selective pressures.
From page 232...
... The idea that culture is fundamentally a kind of inheritance system that can be investigated using "population thinking" has been very productive. it led evolutionary theorists to model cultural evolutionary process by drawing tools and inspiration from fields as diverse as population genetics, epide miology, ecology, game theory, and stochastic processes (Cavalli-sforza and Feldman, 1981; Boyd and richerson, 1985)
From page 233...
... several of the forces that act on cultural variation to cause cultural evolutionary change include ones familiar to evolutionary biologists, such as random errors in teaching or acquiring items of culture (mutation) , statistical effects in small populations (drift)
From page 234...
... By making survival and reproduction possible in novel environments, a system of phenotypic flexibility can expose genes to selection. Thus, presumably, the anatomically modern human populations that left tropical Africa to invade temperate and periglacial environments in eurasia adapted first to them using clothing, shelter, and fire, but later also evolved husky physiques and lighter skin pigmentation adapted to cold temperatures and low light (Jablonski and Chaplin, Chapter 9, this volume)
From page 235...
... argues for systems of morality, or did culture commonly play leading roles in gene–culture coevolution, even in the evolution of the earliest hominins? Perhaps human nature itself is substantially a product of cultural evolution influencing human genetic evolution by a systematic, large-scale Baldwin effect.
From page 236...
... . in anatomically modern humans, at least to judge by well-studied ethnographic examples, adult male hunters produced a large surplus of meat and fat that was channeled to women and children (Kaplan et al., 2000; hill and hurtado, 2009)
From page 237...
... . immediately after anatomically modern humans left Africa, most populations seem to have been making Middle Paleolithic artifacts but, a short time later, the Upper Paleolithic peoples of western eurasia made sophisticated tools and produced a large corpus of art (Foley and lahr, 1997)
From page 238...
... grounds, the fact is that the large brain of anatomically modern humans predates the Upper Paleolithic cultural system by perhaps 150 kya. Perhaps chronically low population densities prevented the cumulative cultural evolution of highly complex tools and symbolic behavior that characterize the Upper Paleolithic and later stone Age (Powell et al., 2009)
From page 239...
... The LCT regulatory gene downregulates the secretion of lactase postweaning in most human populations. in western eurasian and African dairying populations the gene is rendered nonfunctional, so that adults continue to secrete lactase and to benefit from lactose.
From page 240...
... in the case of genes with strong and direct phenotypic effects, such as LCT, HBB (the sickle cell gene) , other genes coding for resistance to malarias, skin pigmentation genes, and a few others, a functional understanding of the genes preceded genomic analysis, which has added only wrinkles to the classic stories.
From page 241...
... laboratory artifacts, (ii) introgression between neandertals and anatomically modern humans (Plagnol and Wall, 2006)
From page 242...
... . increases in mammalian brain size averaged over many lineages might be taken as a paleoclimate index of the amount of high-frequency environmental variation, on the grounds that costly nervous tissue would not evolve unless useful for adapting to high-frequency environmental change by individual learning and simpler forms of social learning (Aiello and Wheeler, 1995; reader and laland, 2002; sol et al., 2005)
From page 243...
... The way forward will be to make optimal use of all three forms of data, each with inevitable limitations, in evaluating hypotheses about our evolution. Current Selection Most but not all contemporary human populations have experienced rapid and dramatic cultural change in recent times due to economic development and the globalization of culture.
From page 244...
... A number of genes that might be targets of selection are known to be involved in asthma. some of the complexities of gene–culture coevolution can be illustrated by the impact of the demographic transition on genetic and cultural evolution.
From page 245...
... . Dense populations also led to the cultural evolution of new forms of social organization to replace the smallerscale egalitarian societies that typify many hunter-gathers.
From page 246...
... on the other hand, culture is a tremendous force for generating behavioral variation independently of genetic variation. Thus, human genetic variation for behavioral traits may be large because cultural variation shelters much genetic variation from selection.
From page 247...
... Theory points to the speed of cultural evolution compared with genetic evolution. even rudimentary culture capacities could support appreciable amounts of culture-driven gene–culture coevolution.
From page 248...
... in western eurasia and northern Africa, anatomically modern populations began making sophisticated Upper Paleolithic stone tools and art objects about 40 kya. ephemeral episodes of more sophisticated tool making do occur much earlier in Africa (Jacobs et al., 2008)
From page 249...
... . By now it is clear that much of the genetic variation and genetic diversity in human populations is consistent with a spread out of Africa about 60–50 kya (ramachandran et al., 2005; liu et al., 2006)
From page 250...
... even the anatomically modern humans that left Africa and moved eastward to eastern eurasia and Australia did so using relatively simple Middle Paleolithic toolkits (Foley and lahr, 1997)
From page 251...
... and anatomically modern humans and neandertals (ruff et al., 1997)
From page 252...
... . Thus, there are hints, but at this point only bare hints, that changes in climate variation were increasing selection in favor of more sophisticated culture capacities.
From page 253...
... Evolution of Language and Social Organization language and social organization were probably closely related in the course of human evolution. Much of our use of language is related to social life, and it is reasonable to assume considerable parallelism in their evolu tion (Dunbar, 1996)
From page 254...
... Although the involvement of the FOXP2 gene in language evolution has turned out to be complex and controversial, the intense interest it has generated illus trates the questions we hope to answer with the help of genomic methods: What genes changed, when did they change, and what is the functional significance of the changes? Many scenarios have been advanced in discussions of the evolution of social organization, although it has not received the same amount of attention as language.
From page 255...
... CONCLUSIONS Genomics has already made quite substantial contributions to our understanding of human evolution, beginning with the use of mitochon drial DnA variation to understand the timing of events in recent human evolution and to provide a window into human paleodemography, including past population sizes and migration patterns. The use of linkage disequilibrium to identify genes under recent selection suggests a mas sive holocene wave of genetic change initiated by the cultural evolution of agricultural subsistence.


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