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Not just in terms of selecting genes, but also selecting cultures. If allele A causes increased desire to reproduce than allele B, then in a society in which reproduction is viewed as an optional extra, all else being equal, allele A is likely to predominate allele B over time. Conversely, in a more traditional society in which everyone is subject to a strong social expectation to reproduce, allele A would have far less of an advantage over allele B. An allele might lead to increased reproduction indirectly rather than directly. For example, if an allele makes a person more likely to be religious, and if religious people are more likely to have kids, then even though that allele does not directly impact desire to reproduce, it may be selected for due to its indirect impact on reproduction. That's genetics; coming to culture: if subculture A puts higher emphasis on reproduction than subculture B, then all else being equal, in the long-run subculture A is likely to outnumber subculture B, irrespective of any genetic factors. However, defections from subculture A to subculture B may erase much of its innate demographic advantage. This suggests in the long-run, the most demographically successful subcultures will be those which combine sustained high fertility with sustained insularity (social barriers to defection to other subcultures)–which is exactly what we observe with groups like the Amish and ultra-Orthodox Jews. |