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June 15, 2005

The Urban Sink

In Empirical flesh on logical bones I expressed caution at the free wheeling Darwinian logic of selection that some use when viewing historical trends. I focused in particular on the conjecture of a man I admire a great deal, R.A. Fisher, who surmised that the victory of Christianity and Islam over the classical world could be attributed to their pro-natalism. That is, while Christians and Muslims reproduced themselves, the pagans did not. Though this line of thinking has been more subtly extended by others (see Rodney Stark's The Rise of Christianity), I believe that the model is far too simple to explain the phenomenon it purports to explain.

Taking a natalist line of thinking one might wonder what the future of cosmopolitan bohemians might be? One explanation for the persistence of cosmopolitan bohemians who live for their art and fail to reproduce is to notice that Mormons are prone to a great deal of churn (conversions in and out). That brings me to something I have wondered of late: are people today far more prone to idealize country living because that is their natural preference? My reasoning is this: until the spread of vaccinations and antibiotics it seems plausible that evaluated over the course of history urban areas have maintained or increased their population through migration from the rural areas, not through growth from within through the fecundity of urbanites. Unless a peasant became Sargon of Akkad and sired dozens of sons it seems possible that migration to an urban area might have decreased their reproductive possibilities, and so the fitness of the alleles they carried. Could not a "stay away from the city" allele have proliferated in such a fashion throughout the vast swath of the Eurasian oikomene where cities have been a persistent feature of civilized life for ~4,000 years?

I offer the possibility not in great seriousness, but, I do wonder in the generality about the effect that "civilization," broadly speaking, has had on many peoples throughout Eurasia or Mesoamerica (civilization implying at the least literate urban-focused polities). More specifically, I am curious as to the validity of the impression I have that urban areas might have been population sinks which would likely as not lead to evolutionary extinction for alleles attracted to them.

Addendum: Variables...the selection coefficient, what is a greater danger, famine or plague, over the long term? Are cities truly insulated from famine because of better planning? It seems that the proportion of the population that was urban was rather small for most of human history, so that would weight against it being a significant force for selection. Time...varies by region, in Mesopotamia we are working with over 160 generations, and though gene flow between populations is certain, urbanization through the Fertile Crescent was ubiquitous (so how great an impact did the Guti, Kassites, Amorites and Arabs have on the indigenous substrate?).

Postscript: Some might wonder about this post and its relationship to the recent controversy over the "Jewish Question" (broadly speaking). I have stated in personal correspondence that much of what is "Jewish" might be the consequence of European Jews being urban for so long, that their behavorial tendencies are simply a reflection of a group of individuals totally shaped by urban mores for many generations. I also tend to agree with scholars who offer that without the special role given to Judaism in orthodox Christianity (a role the Marcionites rejected in the early Church) the Jewish religion (ergo, people) as we know it would not have persisted into the modern era in its robust and distinctive form (I will offer evidence from the Jews of China and India to back up this contention at a later point). Suffise to say that just as Christianity is contingent upon Judaism, I believe that Judaism in its own way is contingent upon Christianity, that it is to Yeshua (and Iraenus, Augustine of Hippo, etc.) Jews should look to as the source of the grace given their cultural-complex over the generations, and not Adonai.

Related: Some might find this recent essay in PLOS of interest: The Evolution of Norms (I think a more "cognitive" approach would be more fruitful than the one the essayists point to, that is, the human mind is a biased transmission vehicle and will canalize toward certain norms because of mental constraints and preferences above and aside from the norms' value in social or environmental contexts. This I think this is a better expalantion for "maladaptive" universal culture traits than many of the alternatives, at least as part of a synthetic approach).

Posted by razib at 03:18 PM