Aspect Ratios of Historical Societies

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Abstract

In his book Guns, Germs, and Steel, Jared Diamond proposed that societies grow in accordance with regional differences in climate, and that because climate varies more drastically when moving north-south than when moving east-west, large societies will grow faster east-west than north-south. I characterize aspect ratio for regions on the globe and find that societies are on average wider than they are tall, supporting Diamond's claim. However, I also find a similar effect with small and large societies, suggesting another underlying cause. I then investigate the first part of Diamond's claim, and find that societies do not grow in accordance with climate in the manner he predicts.

The figure above shows the approximate borders of the Rome in the year 129 BCE (in red), and a disk with the same land area and center point (in blue). By comparing the climate diversity within the red and blue regions, I can measure the extent to which the shape of Rome was influenced by a bias toward climate uniformity. I perform this analysis with a thousand historical and modern societies in the second part of the full paper.