That's because cultures change on timescales of centuries. If it works at all like gene transmission works, it isn't worth adapting the culture : one of the cultures will die out in less than the time it would take to adapt.
Your comment seems to carry assumptions about the granularity at which transmission works, which aren't appropriate for memes. Bacteria can gain the immunities from other bacterial species through plasmids. In the same way, people can appropriate ideas from other cultures/sub-cultures.
This is called "island species" : where there are barriers that prevent gene/meme transmission
What the historical record would suggest, is that effective barriers to memetic transmission are the exception rather than the rule. It's even more the exception in the era of the Internet.
Racism occurs because only a single group lives in an area.
Racism comes from outgroup psychology operating on signals involving race/ethnicity. I'd say that racism doesn't exist where there is no awareness of racial difference. (In those situations, classism and other forms of internecine prejudice can arise.)
It is theorized that for memes, racism is one such boundary.
Please give examples of memes for which racism acted as an effective boundary. Racism seems to have zero boundary effect in Japan and Korea, though their traditional cultures once institutionalized racism.
EDIT: Also, recent research has revealed that biological evolution can be detected in large mammals on the timescale of only several centuries.
Your comment seems to carry assumptions about the granularity at which transmission works, which aren't appropriate for memes. Bacteria can gain the immunities from other bacterial species through plasmids. In the same way, people can appropriate ideas from other cultures/sub-cultures.
This is called "island species" : where there are barriers that prevent gene/meme transmission
What the historical record would suggest, is that effective barriers to memetic transmission are the exception rather than the rule. It's even more the exception in the era of the Internet.
Racism occurs because only a single group lives in an area.
Racism comes from outgroup psychology operating on signals involving race/ethnicity. I'd say that racism doesn't exist where there is no awareness of racial difference. (In those situations, classism and other forms of internecine prejudice can arise.)
It is theorized that for memes, racism is one such boundary.
Please give examples of memes for which racism acted as an effective boundary. Racism seems to have zero boundary effect in Japan and Korea, though their traditional cultures once institutionalized racism.
EDIT: Also, recent research has revealed that biological evolution can be detected in large mammals on the timescale of only several centuries.