Department of Biology, University of North Carolina, Chapel Hill, USA.
North Carolina Museum of Natural Sciences, Raleigh, USA.
Sci Rep. 2017 Mar 2;7:43869. doi: 10.1038/srep43869.
Humans, like all organisms, are subject to fundamental biophysical laws. Van Valen predicted that, because of zero-sum dynamics, all populations of all species in a given environment flux the same amount of energy on average. Damuth's 'energetic equivalence rule' supported Van Valen´s conjecture by showing a tradeoff between few big animals per area with high individual metabolic rates compared to abundant small species with low energy requirements. We use metabolic scaling theory to compare variation in densities and individual energy use in human societies to other land mammals. We show that hunter-gatherers occurred at densities lower than the average for a mammal of our size. Most modern humans, in contrast, concentrate in large cities at densities up to four orders of magnitude greater than hunter-gatherers, yet consume up to two orders of magnitude more energy per capita. Today, cities across the globe flux greater energy than net primary productivity on a per area basis. This is possible by importing enormous amounts of energy and materials required to sustain hyper-dense, modern humans. The metabolic rift with nature created by modern cities fueled largely by fossil energy poses formidable challenges for establishing a sustainable relationship on a rapidly urbanizing, yet finite planet.
人类和所有生物一样，都受到基本的生物物理规律的制约。范瓦伦预测，由于零和动态，给定环境中所有物种的所有种群平均流动的能量数量相同。达穆特的“能量等效规则”通过显示在面积上每单位能量需求的小而丰富的物种与高个体代谢率的少数大型动物之间的权衡，支持了范瓦伦的推测。我们使用代谢缩放理论来比较人类社会中密度和个体能量使用的变化与其他陆地哺乳动物。我们表明，狩猎采集者的密度低于我们体型大小的哺乳动物的平均密度。相比之下，大多数现代人集中在大城市中，密度高达狩猎采集者的四个数量级，但人均消耗的能量高达两个数量级。如今，全球各地的城市在每单位面积上消耗的能量比净初级生产力还要多。通过进口维持超密集现代人类所需的大量能源和材料，这是可能的。由化石能源驱动的现代城市与自然之间的代谢裂痕，给在快速城市化但有限的星球上建立可持续关系带来了巨大挑战。
