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Abstract:We propose a conceptual model that maps the causal pathways relating biological evolution to cultural change. It builds on conventional evolutionary theory by placing emphasis on the capacity of organisms to modify sources of natural selection in their environment (niche construction) and by broadening the evolutionary dynamic to incorporate ontogenetic and cultural processes. In this model, phenotypes have a much more active role in evolution than generally conceived. This sheds light on hominid evolution, on the evolution of culture, and on altruism and cooperation. Culture amplifies the capacity of human beings to modify sources of natural selection in their environments to the point where that capacity raises some new questions about the processes of human adaptation.Keywords: adaptation; altruism; cooperation; evolutionary psychology; gene-culture coevolution; human evolution; human genetics; niche construction; sociobiology by the failure of Lamarkism. The so-called Weismann barrier effectively stops genes from being affected by any of the acquired characteristics of phenotypes, including the culturally acquired characteristics of human beings (Mayr 1982). Modern molecular biologists do interfere with genes directly on the basis of their acquired scientific experiences, but this innovation is too recent to have had any impact on human genetic evolution. The failure of this route therefore left only the second alternative, which encouraged sociobiology's claim that phenotypes of all species, including our own, reduce to "survival machines" or "vehicles" for their genes (Dawkins 1989) and that the only role phenotypes play in evolution is to survive and reproduce differentially in response to natural selection and chance. This subordinate status for phenotypes does not cut off human culture from human genetic evolution entirely, insofar as it still allows culture to contribute to human adaptations (Alexander 1979) and hence to genotypic fitnesses. However, according to this perspective, culture has no power to codirect human genetic evolution through active modification or creation of selection pressures.Other evolutionary biologists maintain that culture frequently does affect the evolutionary process, and some have begun to develop mathematical and conceptual models of gene-culture coevolution that involve descriptions not only of how human genetic evolution influences culture but also of how human culture can drive or codirect at least some genetic changes in human populations (Boyd & Richerson 1985; Cavalli-Sforza & Feldman 1981;Durham 1991;. These models include culturally biased nonrandom mating systems (see, e.g., Aoki & Feldman 1997;Durham 1991;Laland 1994), the treatment of human sociocultural or linguistic environments as sources of natural selection (Aoki & Feldman 1987; Cavalli-Sforza & Feldman 1983), and the impact of different cultural activities on the transmission of certain diseases such as malaria and sickle-cell anaemia (Durham 1991). The common element among these cases is that...

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