Friday, February 02, 2007

Why agriculture?   posted by Razib @ 2/02/2007 06:25:00 PM

The post on the thrifty gene hypothesis made me reconsider an issue I've mulled over the past few years: if a transition to an agricultural lifestyle increased the median life misery index, why did it supplant hunter-gathering? (and in most cases, nomadism as well) I think the easiest way to understand how farming could spread despite its relative misery is to use something from the contemporary world as an example. Consider two sisters. One is very bright, and pursues a professional career track and becomes a pillar of the community by 40 as an independent and successful woman. The other isn't bright enought to finish college and becomes pregnant by her boyfriend. I think the expectation might be that someone with career satisfaction, economic freedom and social status might be "happier" than someone who lacks these things. That being said, the structural necessities of being a professional woman mitigate against reproduction. Over the long term the choices which will become normative will be those that amplify fecundity. The hunger-gatherer lifestyle, in general, is constrained in regards to average increase of a population. Mobile groups simply can't support larger numbers of small children. In contrast, sedentary farmers have a bit more freedom in this regard. Over time, no matter the differences in misery index between farmers and hunter-gatherers, the future belongs to those who are most fecund. Eventually other factors will also come into play, the higher densities of farming communities will likely result in the incubation of more lethal pathogens than possible at hunter-gatherer densities, so the "wave of advance" of farmers would also likely be foreshadowed by the die off of hunting & gathering communities who come into contact with the farmers. Cultural diffusion can also work simply through differential reproduction of indigenes who are "adopters" and those who are not. The record shows that farming took thousands of years to spread from the Middle East to Northern Europe, so the process was likely very gradual and undiscernable in many locales (in many areas farming and hunting and gathering were facultative activities, as attested by the eventually closing off the "King's Woods" by elites).

Addendum: In After the Ice Steven Mithen argues that agriculture was in part a response to harsher conditions after an initial expansion of hunter-gathering sendentarism in the Middle East 10,000 years ago. Mithen argues that farming was the only way for communities to support the higher population densities when ecological changes resulted in a decrease in the numbers of the game animals which they had previously depended on to maintain a relatively luxurious lifestyle with a local elite which consumed surplus production. The details are, to me, fundamentally irrelevant. The key point is that farming need not be the acquisition of a "superior" cultural practice on a conscious level, rather, its somewhat higher long term natural increase would inevitably result in "waves of advance" in demographics so that hunter-gatherers would be marginalized. I think it is instructive that traditionally hunting was the passtime of leisured elites, and no nomadic peoples exhibited any inclination to settle down and farm unless forced to by military defeat.