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Sep 04, 2008


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Even historically, 'median value food production capacity' per se has not been the main constraint on the food supply.

Instead, there have been two main constraints on the food supply, and they all relate to how food and population interact.
1. The population is constrained by the minimum food available over any given month. A person can't survive much longer than that without food.
2. The population producing food in a region has to be able to survive in that region all the time, so they can produce food some of the time. This is what made the 'realized niche' and the 'theoretical niche' different for farmers.

The ability to distribute and store food can allow a region that can only produce 2 months of the year, but produces well, to be arable.
The ability to distribute and store water often allows a dry region that would only be arable 2 months to be arable 12 months.

So, distribution networks allow us to average over space, and storage allows us to average over time. As more and more regions come 'on-line' they become productive, raising the median values; and storage and distribution become even more critical, making more areas habitable and arable.

Cities may concentrate population in an agriculturally unproductive zone, relative to population density, but if they provide distribution nodes, they can create a wide zone around them that not only supports them, but supports the entire region.

A disruption in water (or temperature or something else critical) often leads to a famine in areas that were otherwise ok. Perturbations will come, on small and large scales, and with varying frequencies. Small perturbations come often, large ones rarely. We can't do our analysis on a scale independent of our understanding of perturbations. They will be related. If people are settling an area on the scale of centuries, then perturbations that reduce the production of a region once every century to a level that restricts the food supply for over a month will determine the viable population - and yet, that population will probably get decimated once every millenia by an event outside our analysis. If people settle more quickly, and are more mobile, they will raise the local population to a local maxima more readily (a higher maxima) and will flee before a coming famine more often. If there are ample independent available refuges for them to flee to, then what we will see is mass migration. If not, mass death. Migration is more rapid than reproduction, in general, so if people can move (and effectively be stored) we should see higher overall global populations.

All of this is far beyond the ken of Malthus or even most modern media commentators who know nothing of dynamics, systems engineering, etc.

Michael W. Kruse

Thanks for these helpful insights, Ben. I've been trying to write in the most generic terms possible. Your two main constraints incorporate the issue of environmental resources available to any given society; something I haven't raised yet but plan too later. I may be "stealing" some of your summary here for a later post. :-)


I have no problem with you appropriating my summary... actually, it would be great if we could add to it, to really assemble something that people can understand about why, for instance, great famines plagued China in the end of the Imperial period (transportation breakdowns) or Africa in the world today (transportation/distribution breakdowns); how things like ready immigration and free trade can ameliorate many of these problems, but perturbations exist on enough time scales that nothing can prevent crises in the long run without otherwise continual inefficiencies...


Michael W. Kruse

My plan is to come to some of these issues after laying out this basic model. However, I'm willing to bet you probably have a far greater repertoire of examples than I have. :-) If I can get folks interested in the dynamic complexity of it all, rather than sound-bite solutions, then I'll be happy.

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