Agriculture and cultural ecology

I didn't want to post this in the referenced thread, because it would be thoroughly off-topic even for me. However, I would like to address one error in speel-yi's most recent exchange (post 88), and it has bearing on the "cultural ecology" aspect, so may be more appropriate here. Fallowing is standard practice for both swidden and sedentary agriculturalists throughout the world, in many environments. Except for the length of the fallowing period, it has nothing whatsoever to do with rainfall and everything to do with depletion of soil nutrients. Traditional land-use in tropical forest environments, for example, requires the migration of agriculturalists from one forest patch to another after as few as three years due to soil depletion. The abandoned patches are left fallow to be re-occupied as much as 25 years later when the forest has had a chance to re-seed. Semi-nomadic agriculture, sometimes known as "bush farming", is highly density dependent. As population densities increase, fallow time shortens, and alternative regeneration methods (such as planting legumes or grasses) are increasingly used. Eventually this pattern continues until fallow periods are reduced to the point that soil degradation has substantively reduced local productivity, leading to boom-bust population cycles. I highly recommend Jolly and Torrey, eds, 1993 "Population and Land Use in Developing Countries", National Academy Press, Washington, which contains both a brief overview of this pattern and specific case studies from around the world.The point to bring out here is that higher population densities induce changes in cropping patterns and intensification of agriculture. All of which is based on soil productivity. There's an interesting debate in ecology concerning which came first: population growth or agricultural intensification. The traditional, Malthusian idea that an evolution of agricultural technology and innovation brought about a population increase is challenged by modern scientists like Ester Boserup among others, who states that agro innovations were driven by higher population densities. (I haven't read the book, but the most common citation is Boserup, 1965, "The Conditions of Agricultural Growth: The Economics of Agrarian Change under Population Pressure", Aldine Press, Chicago).In any event, it's not rainfall that is the key, and the fallowing idea certainly not original with the Levant.

True, as far as it goes. However, it is very much a question of acclimation. Even those, like myself, whose recent genetic legacy owes more to northern/central Europe (Scots, English, German) find little difficulty in living in the tropics after a certain amount of time (in my case, it took about six months). However, without that acclimation period the risk of heat prostration is quite high. This probably has to do, as John has been noting, with our remote ancestors all having evolved in a hot climate. Even then, it depends on what other adaptations have taken place. I think an Inuit, for instance, would have great difficulty living/surviving in the tropics, regardless of the amount of time spent acclimating, as they have phenotypical cold adaptations that are exactly the opposite of the requirements for a hot climate (Allen's and Bergmann's Rules).