Sunday, October 28, 2007

A noisy optimum   posted by Razib @ 10/28/2007 12:47:00 AM

Reading The Pursuit of Glory: Europe 1648-1815, and something reminded me of my post The Persistence of Bad Habits:
...To put the statistic another way, the net calorific value of the potato is 3.6 times that of grain....
The potato was also less vulnerable to adverse weather than most other staple foodstuffs...A community that could fall back on potatoes when this happened was a community that had freed itself from the thread of famine...governments were keen to promote its cultivation. For reasons that are still not clear, their efforts bore least fruit in France...In Tolouse, for example, Robert Forster found that peasants would not even feed potatoes to their pigs, for fear that their meat would be contaminated...The French were not, of course, alone in their prejudices. In 1770 famine-afflicted Neapolitans refused to touch a boatload of potatoes sent as a gift; burghers of Kolberg in Prussia told Frederick the Great, 'the things have neither smell nor tatse, not even dogs will eat them, so what are they to us?'; and Russian peasants distrused the potato because it was not mentioned in the Bible....

The author notes that potatoes were brought back from the New World in the 16th century, but there was still strong resistance across most of Europe with the exception of the British Isles (especially Ireland) to their cultivation as late as the 18th century! In part this seems due to the structural biases in the way the peasants of Europe made their agriculture decisions and controlled their land. Communal consensus was critical and traditionalists could in practice veto innovation. In places like Russia the peasants were invariably on the margins already and so were especially suspicious of change, and they distrusted their overlords for whom they tilled the land only grudgingly. If there was such resistance to change in early modern Europe, one can not be surprised that agriculture took 4,000 years to spread across the continent!

Nevertheless in the long view peasant resistance to change was probably not totally irrational. As I noted above there was a particularly strong fixation upon custom and tradition in the marginal lands of Russia where communities were extremely risk averse. And Ireland is to some extent an illustration of the "Malthusian Trap" that Greg Clark pointed to in A Farewell to Alms, their acceptance of a productive new crop resulted a population increase which subsequently was subject to a famine of more massive scope in the 19th century when the potato crop did fail. Clark's point that innovation for most of human history did not result in anything more than transitory gains in quality of life; more production was invariably consumed by natural increase in population after several generations. This explains how farming became the dominant lifestyle of human beings when the preponderance of evidence suggests that it is, for the typical human, inferior in quality of life measures (leisure, nutritional balance, etc.) to that of the hunter-gatherer. For farming communities on the expanding frontier life was invariably one of health & wealth, perhaps exemplified in our recent past by the fecundity and robustness of the typical American. The United States is such a young country that just as our frontier closed and the Malthusian Trap should have sprung an economic revolution in human history had already swept that inevitability aside; productivity kept increasing and fertility started dropping.

But the psychology of the 18th century is in some ways still operative today. We are a species subject to fad and fashion, but when it comes to food old habits are often the last to die. And so they should be, what we put in our bodies is one of the most important set of decisions we make over our lifetimes. The aversion to GMOed foodstuffs and a preference to "authentic" and "organic" crops have many causes, but one of them is simply a romantic attachment to the ways of our ancestors (or at least what we perceive those ways to be!). Of course the consumer society is different from a peasant society, and so some elasticity in preference exists which might not have been found in the past simply because the craving for the exotic and novel loom much larger in the minds of humans who don't live on the margins of famine.

A bigger question is to what extent societies are functionally adapted to their local ecologies as opposed to a flux of partly arbitrary norms which serve as the primary environment for individual fitness. Consider the idea that consumption of beef, and meat in general, in South Asia was an adaptation to local ecological conditions. Cattle were critical as producers of milk and draft animals. Meat is subject to spoilage in tropical conditions. So the ban on beef and vegetarianism are local adaptations. The problem with this idea is that it seems that both these practices were concentrated in the elite reaches of Indian culture until relatively recently, with adoption of non-consumption of beef being a hallmark of tribal assimilation into Hindu society and vegetarianism as indicative of Sanskritization on the part of lower castes attempting to move up the ladder of status & purity. In other words, if particular customs were adaptations to local ecological constraints, it is surprising that the groups which were least subject to these constraints propagated the practices. Wealthy families after all could afford wastefulness and conspicuous consumption to signal their attainment of material security. Rather, some have suggested that in fact the socially marginal consumed beef because their options were so few, while only the wealthy should afford a relatively well rounded vegetarian diet which substituted for the density of meat and did not result in nutritional deficiency.1

This is not to say that all functional arguments are irrelevant. Spiciness of cuisine correlates strongly with local climatic conditions after all. But many more local idiosyncrasies may simply be particular norms & values which serve as totems for elites, and which spread downward via emulation. The fact that baby names tend to drift like neutral genes illustrates that important and socially significant culture products can be relatively unconstrained by anything except for fashion. Of course one must add a layer of historical context to these models; the correlation between Old Testament names and Puritan religious beliefs in 17th century England and America is no coincidence. But in this case it illustrates that different social groups may have different norms, and to optimize individual fitness and increase social acceptability within the group one selects or is born into one must adhere to the norms of the group. Ecology is secondary to sociology.

In evolutionary biology processes such as runaway sexual selection are subject to constraint due to the decrement in fitness that they imply at the boundaries. The most extreme case is a population which simply goes extinct due to the extremity of their preferences. Consider a sequence of generations subject to runaway sexual selection concurrent with years of ecological productivity. Subject to weak fitness constraints one can imagine a population shifting in phenotypic value so as to be extremely maladapted when the environment regime becomes less favorable. Nature corrects. And so does human culture; sects which are celibate, such as the Shakers, often have short histories. During times of religious ferment they may draw upon a large base of recruits, but when society wide fervor declines they may find that their cultural strategy is just unsustainable. But the sample space of strategies which humans can engage in is enormous even if you remove the ones which are relatively sensitive fluctuations in the environment. One can still leave room for functional constraint upon cultural forms and still adhere to the hypothesis that most cultural variation serves the role of horizontal group demarcation

Addendum: The Pursuit of Glory is a very good book by the way. It is a good balance of social and narrative history, with a bias toward the former.

1 - Note that being a non-vegetarian does not imply meat consumption every day in the pre-modern peasant societies of Asia. Rather, it means that on occasion one may consume meat, but it is a rare luxury.